There is a very well reviewed device already available, I have one, it flat out works, built by a fellow forum member. http://www.hdconnection.com/Products.htm
This doesn't mean I won't try Beun's when/if its ever done, but in the mean time, I can enjoy my JVC HD deck with Petr's wonderful transcoder.

gn2 wrote:
> There is a very well reviewed device already available, I have one, it flat out works, <

Paul, Petr's unit sounds like a great option, well-engineered and at a relatively affordable price. Unfortunately, for some of us that price is still out of reach. Which is why we're patiently waiting for Kim to come up with a quality option for under $200. Initially, it was suggested that Petr's pricing was in Canadian dollars, which would have mostly eliminated the need for Beun's transcoder. But at US dollars, that still leaves the low-end open for Kim to fill, at 1/2-2/3 the price.

In the mean-time, I'll limp along with a cheapo $50 transcoder (sharp, with plenty of bandwidth), and do the green-tint correction in the PJ.

- Tim

Oh yeah, I totally agree with you on the pricing, it sucks, thats likely why I'll buy one of Beun's if/when its done, just to support the cheaper alternative. I'm ALWAYS in support of the cheaper alternative.

I am still working on this although I would have to agree with all of you that is goes (too) slow. The new schematic is finished, I have already tested the micro-controller program and it works. Currently I am working on the PCB layout. I have a few other priorities to take care about but I will try to finish it within the next few weeks.

Thank you guys for reminding me that people are still interested.


Kim

Looking forward to seeing if Audio Authority's upcoming Component-to-VGA transcoder works well, as my KD-CTCA1 never did a very good job when it comes to playing XBox games on my computer monitor:

http://www.digitalconnection.com/products/video/9a65.asp

Davin8r,

thanks for the info on the upcoming AA HD-capable transcoder. I'm happy to see that they're responding by bringing out a new model, and hopefully it won't suck. :) The price is certainly attractive.

One problem I see with it right away for many setups is that though it has a component-video pass-through (unnecessary for most), and dual VGA outputs (handy in some cases), it has no VGA pass-through (which most will need that don't have extra VGA switcher inputs available).

I still think the unit that Kim is perfecting will be (functionally) superior to the new AA, even if it costs a bit more. And I won't be surprised if it's better from a PQ standpoint as well.

- Tim

Beun commented:
> I am still working on this although I would have to agree with all of you that is goes (too) slow. <

I think most of us here are understanding of your development constraints, and while we'd love to have had it long ago, we're happy that you're continuing to work on it, and will be very pleased when it's complete.

> The new schematic is finished, I have already tested the micro-controller program and it works. Currently I am working on the PCB layout. I have a few other priorities to take care about but I will try to finish it within the next few weeks. <

That would be wonderful.

> Thank you guys for reminding me that people are still interested. <

Very much so. Your persistence is greatly appreciated.

- Tim

Originally posted by littlebeancurd
Anyhow, my friend bought a transcoder, a KeyDigitalSystems one. It's the KD-XB Xblaster, made for game systems and mostly for the XBOX.

Anyone know why it's not working on that NEC plasma? I hooked it up to a computer LCD and it worked just fine.
Most likely, the plasma display can accept either a component signal or an RGBHV signal through the same input connector(s). If this is true, it probably auto-switches to component mode when it detects sync on the G signal of the KD-XB (same input as Y in a component signal). Or, just the presence of that sync on the G output, when there is none on the R or B outputs, is causing level problems on the plasma display that the LCD is able to ignore.

Removal of the sync from the green output is usually critical for these conversions, and the KD-XB does not do it.

Kim-

I am also 'still very interested' in your project-I am glad to hear you are making progress, at any speed.

Long time no hear from me, but I just send off the new board layout to be manufactured. It should arrive early next week. Let's see if this works as expected.


Kim

Oh, very good news, I'm excited to see the results of all this time and research you've done, Kim. I've been using Petr's transcoder, and it is excellent, but I'm still excited to see if anyone else can get it right for a reasonable price.

I've been using Pert's board also but ran into some issues with it regarding black clamping, horizontal intrusion in the op 5-8% of the scan, and some horizontal lines near the top. He agreed to accept a return and I will be returning it as soon as he gets back home. I am very interested to see how yours works on my back level variation. There appears to be something about the HD700 and the HD it likes. Loves the DTC100 and my motorola HD200 HD decoder but has problems with the LGE LST 3410A PVR. Keep me informed. BTW, Pert's has a passthrough.

Art,

The final one will have a passthrough as well, don't worry. This first one is just a prototype to test the principle, just a bare board.


Kim

Kim: If you need testers, just let me know, I've got a few sources with component HD out including Dish 6000 sat box, Jvc 3K DVHS vcr, and if you needed it, a Momitsu. Also, I've owned a few of the different cheap transcoders, and currently have Petr's and an Inline, so I've got lots to compare it to.

Oh, I need testers. I can only test this particular one in a lab environment, so I need real life feedback.


Kim

Let me know when you're ready, I'll gladly test. I have several different display devices too so you can see how well it interacts with a presentation monitor, a regular computer monitor, and several different crt video projectors.
Email me direct if you like, my address is in my signature...

I would like to be a tester. My RPTV accepts RGBHV and responds poorly to bright scenes using YPrPb tri-level sync, so converting back to RGBHV with bi-level sync would make a difference for me.

Kim

If you NEED testers, I will test for you. I don't have too many things to test it with but I have a few displays.

Walt

Kim-

I also still wish to help out with testing if possible. I have access to numerous types of displays and signal sources, as well as oscilloscopes, soldering abilities, etc.

All,

I thank you for your continuing support. I will get boards in during the middle of next week. I will see how fast I can solder one together and get the logic for the PLD right. When I get the feeling that it may work, I will put the remaining 4 boards together that may have the make the rounds is more than 4 people would want to help me. When everyting still works than the next step will be to design the complete feature set (before every start to scream pass-through, yes this will be one of the features) and make it a product with a nice case and stuff.


Kim

Kim-

When you have your completed design, I am also interested in a 'board and pile of parts' kit, or even also a 'board, preprogrammed PIC (or just place to download the code), and parts list' version. I hear the term "DIY", and I envision building your design right inside my devices, or maybe hacking a KVM switch to incorporate component-to-VGA internally, and things like that.

That would be no problem what so ever. When everything is finished, I will post all data here.


Kim

Kim,

I was thinking of trying this circuit out. I was looking through the schematics and wondering if there is an error in the final Green Op amp output. The formula you list in the schematic is:

G = 1.3982*Y - 0.2973*R - 0.1010*B

However, it looks like your circuit has:

G = Y - 0.2973*R - 0.1010*B

since the Y comes straight from the buffer amp. Following through on this, if you use the alternative equation you list:

G = Y - 0.4682*Pr - 0.1874*Pb

You could use 1.091K for R22 and 2.727K for R23, or the closest standard resistor values, and connect each respectively to Pr (U8 pin 10) and Pb (U8 pin 12) instead?

Hopefully I am not too late in pointing this out for your circuit boards.

P.S. I would be willing to help test you prototype also if you need some one else.

Ken,

Let me look into this, I thought that I have been very carefull but you never know.


Kim

Ken,

I looked into it and you forgot one thing. The Y signal is amplified by 1+R26/(R22//R23) in which R22//R23 is the parallel connection of R22 and R23. In numbers: Gain(Y)=1+511/1297=1.3938.

Therefore, the formula for green will be G=1.3938*Y-0.1002*B-0.2936*R. I have verified this by simulation , but the measurements will be the proof of the pudding. If I am wrong, a change in resistor values can fix this.


Kim

Kim,

Ooops, forgot that those count in the gain calc.

What are you using to simulate?

I eagerly await your results!

Ken

Ken,

I have the full PSpice suite at my disposal, so I can simulate most of the circuits.


Kim

All,

I just had some time tonight so I finished the up board and after measuring for an hour now I think it works.

I have a rock solid black level clamp and the sync cutter seems to work exactly as planned. If during testing of other resolutions there is need for change, it can simply be done by reprogramming the micro. I will see if can find some time to solder a few more boards together so it can be tested in real life.

By the way, do you guys need positive or negative sync at the output

I will keep you posted.


Kim

My RPTV seems to be able to handle both negative and positive sync, so it doesn't matter for me. It might be good to emulate the sync of the few current STB's with RGB outputs, which I guess would be negative, but I'm not sure.

Barcos usually need negative sync.

Joe L.

Negative/negative will be safest bet so all the old Barco's can use it. I don't think any other projectors are picky.

I believe my DWIN HD700 is negative. BTW, I have a DWIN HD500 that I would like to sell. It is not working but I know the tubes are in excellent shape. If you live in the Washington, DC metro area and need a projector with HD capability, the 500 is a winner. It probably needs a trip back to DWIN for repair. To be pessimistic, figure a $1,000 round trip to California for repairs and shipping. I would sell it for $1,000.00.

The question of sync polarity is only for this experimental board since it is hard programmed in the PLD, for the final version I will make it selectable through a DIP-switch or so. I will see tonight if I can use this thing to hook up a DVD player to a computer monitor. I am afraid I don't own a projector so over the next week or so I will built a few more boards so you guys can try it.

Also can anyone of you just mention the complete wish list again what the final version should be capable of, I kinda forgot already what you guys all wanted to see.

Again, I'm willing to be a tester if you are looking. I have both a Digital cable box and a high definition Satellite receiver as component video sources. I can also compare the unit to a Key Digital transcoder. I would have my HTPC as a RGBHV source to test pass thru, in addition to the same satellite receiver.

My Electrohome 8500 can accept either positive or negative syncs.

I believe people wanted either conversion only so as to save on costs, or to have a switchable RGBHV pass thru input, switched either using IR or RS-232 or such.

This pass thru should be real high bandwidth so as to not be the weak link in a video chain, i.e. capable of passing MP-1 outputs unadulterated. Maybe something like the 160MHz you mentioned, except close to flat or 1dB up to that point, not 3dB.

Ken wrote:
> I believe people wanted either conversion only so as to save on costs, or to have a switchable RGBHV pass thru input, switched either using IR or RS-232 or such. <

To keep things simple (as well as more convenient) I believe that what most were looking for on the pass-through was a simple "switch-on-signal-detect". I.e., the pass-through is switched in whenever there isn't a signal present at the component inputs.

Some may prefer more flexibility than that, but the extra complexity would make that a non-mainstream option. That's my recollection, in any event.

And congratulations, Kim, on the progress you've made!

- Tim

beun asked:
> can anyone of you just mention the complete wish list again what the final version should be capable of, I kinda forgot already what you guys all wanted to see. <

Core functionality:
1) solid Black level clamping at the input
2) correct Sync separation for bi- and tri-level sync (striping all residual sync)
3) an accurate 720p/1080i color matrix
4) wide bandwidth (~160 MHz) and low residual noise
5) automatic RGBHV bypass if there is no sync detected on the YPrPb input
6) RGBHV output with positive/ negative sync or composit sync on H
7) RCA and VGA inputs, VGA output
8) assembled price in the neighborhood of $150 (or bag of parts for less)

Optionally (in order of cost):
1) manual RGBHV-bypass override switch (should be cheap)
2) output-level gain trimmer (to match bypass video)
3) component 480i/480p color matrix
4) BNC outputs
5) BNC inputs
6) switching controlled by IR or RS-232

It seemed like someone wanted a trimmer to adjust some other parameter, but I can't remember what it was, and don't have time to scan the whole thread. Maybe I just imagined it.

[Edit: thanks to Art's reminder, this was: trim pots for hue and saturation calibration.]

Personally, I'd like to see options 1 & 2 in the core product, and for those not wanting the bypass at all (presumably to save a bit), they can build it themselves from a kit. The major option/decision for most folks will be if they want BNC outputs or not.

- Tim

Beun,

The horizontal centering issue causes a lot of problems. perhaps the trim pot was mentioned in this regard. Also, color level is often a problem on sets where there is no color or hue controls other than what you can do with the gray scale tracking. trim pots wherever possible for hue and saturation would be a plus.

Remote switching by IR would be nice but if you have the RGB sync on green presence/absence defaulting the unit to RGBHV, you really do not need it. I prefer VGA/15 pin plugs or BNC but if others want RCA that would be OK too. VGA plugs are supposed to have bandpass limitations below the highest HD spec I believe. I prefer them for convenience but RCA's or BNC's will work too.

Beun, for me, the most problematic issue has been the brightness level shift with changing peak white levels. If you can make your unit put out what the early HD units did in RGBHV, the RCA DTC100 and Motorola HDD200 decoder, I would be grateful. Other decoders including the $300.00+ model available from a member of this forum have not solved this problem. My LGE LST3410A shifts brightness level continuously and predictably as bright spots appear in a scene. the dark background gets brighter, higher IRE.

I would love to test your board because I have 3 units which deliver HD at 1080i. Two of the units deliver at multiple HD levels. These two also are capable of Y,Pr,Pb or RGBHV. The three units are: RCA DTC100 ATSC tuner, LGE LST3410A HD PVR, and a Motorola HDD200 which decodes the MPEG2 bit stream it receives from Motorola cable boxes and C/Ku Band satellite Videocipher II/Digicypher II receivers--the only encoding protocol used for TV broadcast that has not been broken. The quality of the picture from these boxes, the HDD200, is far superior to all other encoding/decoding boxes and schemes such as those used on DVB satellite systems like Direct and Dish. Voom uses DCII but it is compressed to a higher level than the DCII available with 4DTV.

I watch on a 120" diagonal screen using a 3 gun CRT projector. I mention all this because with all these toys I am capable of giving you a very thorough analysis. Please consider me for one of your reviewers.

Art

MrHiFi wrote:
> trim pots wherever possible for hue and saturation would be a plus. <

Bingo, that's what I was forgetting. Thanks, Art. I believe Kim indicated that this shouldn't be a problem to incorporate.

> The horizontal centering issue causes a lot of problems. <

That one I was unaware of. What contexts has this cropped up in? This shouldn't be any more complex than shifting a timing pulse.

> I prefer VGA/15 pin plugs or BNC but if others want RCA that would be OK too. <

RCA connectors were spec'ed only in the context of the component-video inputs. I can't see anyone wanting a VGA connector for these, but who knows. No RCA on the output side.

> VGA plugs are supposed to have bandpass limitations below the highest HD spec I believe. <

I'm aware of that claim, but since I can send 1920x1200p from my PC video card unmolested into my 24" widescreen Sony GDM-W900 HiDef monitor, it's more of an impedance-matching issue, not bandwidth limitation. Purists will prefer the BNC connectors for reduced impedance discontinuities at the cable end points, thus minimizing potential ringing-related problems (revealing greater detail).

> for me, the most problematic issue has been the brightness level shift with changing peak white levels. <

I don't believe this will be an issue with Beun's implementation.

- Tim

Let me go down the list, please remember that this prototype is only a prototype and does not have all the features. It should have all the functionality.



Core functionality:
1) solid Black level clamping at the input ------ Yes
2) correct Sync separation for bi- and tri-level sync (striping all residual sync) ------ Yes
3) an accurate 720p/1080i color matrix ------ Yes
4) wide bandwidth (~160 MHz) and low residual noise ------ Yes
5) automatic RGBHV bypass if there is no sync detected on the YPrPb input ------ Can do
6) RGBHV output with positive/ negative sync or composit sync on H ------ Only negative now can do request
7) RCA and VGA inputs, VGA output ------ Yes
8) assembled price in the neighborhood of $150 (or bag of parts for less) ------ I still need to run the numbers depends mostly on fancyness of the case

Optionally (in order of cost):
1) manual RGBHV-bypass override switch (should be cheap) ------ Can do
2) output-level gain trimmer (to match bypass video) ------ Is possible manually for the separate RGB channels but adds complexity when you want gain tracking
3) component 480i/480p color matrix ------ Complex in same unit easy as different version
4) BNC outputs ------ Maybe, adds cost
5) BNC inputs ------ Maybe, adds cost
6) switching controlled by IR or RS-232 ------ Adds cost and significant development time

Additional questions:

a) Hue, saturation controls ------ Should be gain of Y and Pr, Pb. I can give independent gain control but tracking is more difficult
b) H-centering ------ Time shifting a pulse is possible but requires significant digital logic.

Most of these one time controls like gain matching and input gain are most likely be implemented as documented pots when you open the case. I do not plan to make those available on the outside (cost)

> Core functionality: <

Looks very solid.

> 6) RGBHV output with positive/ negative sync or composit sync on H ------ Only negative now can do request <

This would simply be a set-once internal jumper, but it might be worth asking if anyone really needs a positive option, if it's extra work. Nothing I have requires positive-sync, though most of the ports on my CRTs will only accept negative-sync.

Regarding the options...
> 1) manual RGBHV-bypass override switch (should be cheap) ------ Can do <

I think some will find this quite useful.

> 2) output-level gain trimmer (to match bypass video) ------ Is possible manually for the separate RGB channels but adds complexity when you want gain tracking <

Gain-tracking would make things more convenient, but what I think we're really looking for is the possibility of adjustability to make matching possible. Since this is likely a one-time calibration, I doubt it would justify complexity, cost, and development time. I'd say the easy route is sufficient.

> 3) component 480i/480p color matrix ------ Complex in same unit easy as different version <

I'm not sure how many people even care about this? While having the capability would make the transcoder more full-featured, AFAIK everybody in this thread and most others are looking for something to handle HDTV sources well, not 480p. I wouldn't feel bad at all if it were left out.

> 4) BNC outputs ------ Maybe, adds cost
5) BNC inputs ------ Maybe, adds cost <

I think you need to at least make the case capable of (big enough) to allow substituting BNCs on the output side. For some, this will be a requirement, and a worthwhile enhancement. Minimally, make a retrofit a possibility.

> 6) switching controlled by IR or RS-232 ------ Adds cost and significant development time <

Another item to poll on. I know of only one or two who indicated such an interest. For most, it's not an issue. Adding development time is not something any of us waiting at willing to do at this point (I'd guess).

> a) Hue, saturation controls ------ Should be gain of Y and Pr, Pb. I can give independent gain control but tracking is more difficult <

Just implement the simple/easy/cheap solution. The functionality will be there, and if it's a bit more difficult to set up, it only needs to be done once.

> b) H-centering ------ Time shifting a pulse is possible but requires significant digital logic. <

This would only be important to those with no ability to control this on their display device. How many folks here need this?

> Most of these one time controls like gain matching and input gain are most likely be implemented as documented pots when you open the case. I do not plan to make those available on the outside (cost) <

Sounds great.

- Tim

> a) Hue, saturation controls ------ Should be gain of Y and Pr, Pb. I can give independent gain control but tracking is more difficult <

For those of us who are running RGBHV or RGB direcly into a CRT monitor, there is no way to adjust color and hue to adjust for anomalies in the broadcast other than adjusting the drive and blanking controls at the monitor for each gun. It sure would be nice to have a color and hue control available but I know it is probably beyond the scope of the original idea. On the other hand, it would make this unit unique and very desireable since now it could almost be used as a "control center/switcher". Just a thought.

The VGA connectors are fine for me. Everything looks great otherwise. I'm making room for the first unit.

Some more testing:

I have seen some problems while switching video formats. My DVD-player that I use for testing seems to do this while switching from the menu to the movie. Reading the updated datasheet of the EL4511 confirms that this is a new "feature" and that the IC needs a hard reset while doing this.

The datasheet also gives an example circuit that I of cause do not have on this board. I guess that I than also need to reprogram the IC but I will verify. This is a nuisance and may cause some video glitches. The solution on this experimental board is to pull the power plug for 30 seconds or so and than plug it back in.

I will investigate this further.

Regarding the color matrix, is it different between DTV broadcast 480p (and DVD 480p) versus DTV 720p/1080i, or different between DTV broadcast (all formats) versus DVD 480p/game boxes/whatever?

I would like to see a device that handled all DTV formats, but if that is a complex issue, then just the 720p/1080i version will be nice.

A "build it for either 480p or 720p/1080i" option in the 'kit' version would be nice, if feasible (would it be, say 'replace these three/six/whatever resistors with these other ones'?).

I would add another vote for basic color adjustment controls if possible, but I would prefer BNC's out if possible.
I notice alot of broadcasters seem to have a greenish cast to their HD which isn't present on things like DTheater tapes.

I also would like to see BNC's at least for the output side.

If cost is the issue, then at least making the pc board with a spot to solder pc mount connectors if there is room. This will avoid having to use discrete wiring to connect the BNC's.

I will see what I can do with respect to the BNC connectors, I agree with Ken that PC mount is the preferred way of doing it.

About the color matrix, the whole thing is determined by a handfull of resistors, and these can be changed at any time during the whole process. In the end it is just a matter of calculating the right values for the right color matrix, whatever that may turn out to be. The problem with doubling these up as I do for the VGA->component transcoders is that it adds a lot of extra stuff.

Kim, in another thread, Mike Parker commented:
> The other nice feature to have is sync to video alignment (horizontal position pot). Here is when you're able to get the image brightness and colors at it's best (one good feature on the KDS unit). <

- Tim

I will see if I can write a routine to accomplish this, the biggest problem herer is that I have to go into negative time on the H-sync when I want to do this really nice. When you are only interested in a shift to the left it will be relatively easy.

Kim

Kim,

A shift to the left is what is necessary Forget about shifting to the right...it does not happen.

An update on the status,

Currently I am building 4 boards to be tested by you guys. I am waiting on some more parts to finish this. The boards do the following things right:

1) Rock solid black level clamp at the input
2) Works with bi- and tri-level sync
3) programmable (with micro-controller) sync cutter that removes all sync
4) Wide bandwidth (200MHz or so)
5) Accurate 720p/1080i color decoder (this can be changed on request)
6) Does below black

The board has issues with the following:

1) Because of a new "feature" in the sync-separator chip it needs a hard reset by pulling the supply for half a minute on a video format change. This happens when my DVD player changes from the menu to the movie.
2) For my RPTV the sync pules seem to be a bit too narrow. A Viewsonic LCD screen doesn't have a problem with this. YMMV
3) No fancy stuff like passthrough yet


The issues will be solved on the final release of the transcoder and I am already working on full programmability of everything. Hang in there.

Beun,

Please understand that what I'm going to say is meant in a spirit of positive creativity.

Two of my HD sources incorporate switchable resolutions but in practice the only resolution one must have is either 1080i or 720P. I understand how a DVD player may switch resollutions, mine does, and I manually have to go to different memory locations in my projector and switch the Transcanner in order to see the menus because I own a $1,800+ DVD player, an Elite DV09 which only puts out NTSC not 480P. My Transcanner qudruples the lines so progressive is not an issue I can imagine not being able to see a menu will be a big deal for owners of NTSC DVD players.

My Motorola HD decoder, the HDD200 requires a power down whenever the resolution is changed. This is not really a problem because one never changes the resolution once the best one for the display is selected. I suspect your transcoder will operate the same way except maybe for 480P mode from DVD players that put out that type of signal.

I am concerned about the arrow sync pulses. Some have suggested that the brightness level variation I observe with the LGE LST-3410A may be due to the fact that it's sync pulses are incompatible with the display. Older HD units apparently had wider sync pulses?

Have you looked at the new Transcoders available at copperbox.com? The replacement units for the original KDS unit appears to be a bit more sophisticated.

Art,

The resolution switching is only a problem now because it is a new documented "feature". The final version will detect this and will do the reset and reload automatically. This time that this will take is about one frame.

Regarding to the narrow sync pules, this too will be solved in the final version. I could even forsee that I make this programmable through dip-switches

Hi, just checking to see if there has been any progress made on this. I would be interested in one of these as I want to get the new Motorola 6412 DVR and need a transcoder to connect it to my Sony 1271 projector.

- Brian

I think this died.

Art,

No it hasn't died. I send a few around and although they do kinda work, there are still some bugs to work out. One of them is that the 512 times the horizontal frequency output of the EL4511 sync separator is not generated by a true PLL. It actually swallows some pulses to generate a "average" 512x H-sync frequency. This causes the sync cutoff pulse to produce a jagged edge which for lower quality converters may be acceptable but not for the one that we would like to generate here.

The good news at least is that the color matrix is virtually perfect and that there is no black crush. At this moment making use of the free days around Xmas I am designing a true PLL and a new timing circuit for the sync cut-off.

Please stand by, it is not dead yet.

I am disappointed that you did not include me in your test group.

Art,


Please check your PM from 10/24/04. I never received a response.


Kim

I can still put one together with updated firmware that gets the sync cutout a little bit closer. The "final" (whenever that is going to be) version will of cause have to wait till I solved the PLL issue.


Kim

Kim,

i received no message from you and i would have welcomed one. I wish you good luck and remain available if you need my opinion.

Art,

Please check your PM, it is a resend.

I'm also interested in the progress on this unit. I feed my BarcoData 808 w/ a Momitsu V880, an SA8000HD cable box and the DISH 6000u.

I am also still interested in testing and/or buying one of these devices. I have scopes and other devices and experience available if it is helpful.

I bought a "Vdigi" component-to-VGA transcoder a while back, but it is mediocre quality (low output resolution) despite its listed specs.

I think I spoke too soon that I could built a few more of the old boards, they must have been lost in the moving shuffle. So at this moment I am finishing up the board of hopefully the final design cycle before I only have to change the form factor for the final product.

So at this moment I have made the following changes:

Since I found out that the 512* horizontal frequency of the EL4511 sync separator is not a true constant frequency, I have designed a separate PLL that gets me a multiple of the H-sync frequency so I can generate a sync cut pulse that is truly fixed in time.

The micro-controller now takes care of the reset "feature" of the 4511 and other details that I still may encounter.

I think I can send the new board out in a day or two, meaning I should have the first of the new transcoders finished in a week and a half. Don't despair, in the end this is going to work.


Kim

I'm here for you. Please let me help.

I just send the new boards off to manufacturing, I will keep you posted.

Kim and all,

I'm very interested in this solution. Just spent the last 3 hours reading through the entire thread.

(what a roller coaster ride for you all - and for me especially since my first misperception early in the thread was that it was approaching today and wondering how long I might have to wait to in order to purchase one of these since I have an 811 stb coming this friday - had my years confused. Imagine my surprise after reading the first 1-12-04 post and checking my laptop date several times to wondering how, despite being after midnight it was still only 1-11. I'ts very late - but akin to in years past wrinting wrong year on checks in January. Writing checks - something I haven't done in years.)

So... kept reading (like a book, I'd never cheat by jumping to the end) to find that you might be getting closer (a year later). I commend your persistence. My interest, although a year late might validate continued interest in this product.

I'll continue to follow with high anticipation of your success and hopeful of not to far off availability.

Mark

I just reveived the boards back from manufacturing. I will spend the next several days to put on the components and create the new program for the PIC and the PLD. I will keep you all updated.

Kim,

It sounds like some progress to me.

Hope everything goes together on the new boards as planned.
Quite a few of us wishing we had your skills.

Joe L.

Hi beun,

In one of yourposts you mentioned that the 4089 wouldn't work for HDTV, I'm curious why you say it won't work or didn't work.

Walter,


The Zetex 4089 part has a clamp current that is too small to compensate for the bias droop. According to the datasheet the input bias current is maximally 10uA. The clamp current (restore current in the datasheet) is minimally 180uA.

Therefore, the ratio between the two and thus the ratio between the line width and the width of the backporch clamp signal has to minimally 18. For a 480p signal with a line width of 30us this would mean that the backporch clamp should be 1.6us. This barely happens for a 480i signal where the backporch clamp is normally around 1us wide. For the 480p and higher resolution signals the backporch clamp can be as narrow as 200ns.

Even from a theoretical point of view this will not work, and the measurements showed it.

sound like things are comming along. I am definately interested in the transcoder when things are complete..

Hi buen, Okay, well I wasn't noticing that part of the spec, thanks. Another look at the data sht and its .1db bdw isn't all that great either.
I was looking at your cct and you've got me confused on how your dc restoration is working on the front end. Your using a bkporch pulse to turn on the opamp on when the bckporch arrives so you can get a dc level, but the opamp turns off as soon as the pulse changes state. THe opamp doesn't retain the dc level because the o/p of the opamp is put into a hi Z state with no dc level remaining at the o/p, it needs to have a switch between the o/p of the i/p amp and the cap on the i/p of the dc amp. Am I out in left field on this one, if so please explain how this part of the cct works.
Looks like the same cct that the marquee series of pjs use for dc restoration, only they use a lowly tlo71 opamp with a cmos switch, but its good for dc ccts and works.

Thanks

jradomski

If you mean that I am moving at the pace of a snail in molasses, I suppose you are right :D

Walter,

The capacitor that holds the DC level is the series coupling cap at the input.

Hi beun,are you referring to the .1uf(100nf) at the i/p of each rgb amp? I'm not sure how that works for sampling the backporch dc level and restoring the blk level every line, doesn't make sense to me. If you wouldn't mind explaining this to me, as I have designed a circuit or two in the past for this purpose but I'm not following you on this one.

Thanks

Walter,

Consider the following case:

We are at the active portion of the backporch and thus the error feed back opamp is active. Also assume that the video input at the backporch is not exactly 0V (what it should be) but has a 10mV offset.

The feedback opamp will now charge the input capacitor in such a way to set the output of the signal opamp at a fixed 0V (the reference at the other input of the feedback opamp). When the backporch pulse is over the feedback opamp becomes an open circuit at the output, but the charge on the input capacitor has nowhere to go (except from some small leackage) and will therefore hold the output of the signal opamp at 0V DC with the video signal superimposed on top.

At the next backporch all the circuit has to to is offset the droop caused by the leackage.

Hi Beun, Thanks, I'll have to have another look at the schematic when I get home tonight

Hi Beun, Okay I see what you're getting at. I suppose this would work(i assume it does work or you would have changed it), does the dc restoration opamp not require a fdbk res between the o/p and neg i/p to be stable or this 1399 okay operating open loop for this application. I guess one advantage of this cct over the traditional type is there is no noise added to the dc level restoration by a opamp remaining tied to the i/p stage.

Walter,

The total loopgain of the 2 opamps is only a factor of two higher (caused by the 2x amplification of the signal opamp) than the loopgain of a single opamp, so there should be enough margin. Furthermore, the high output impedance of the 1399 and the 100nF input capacitor form a dominant pole that stabilizes the whole loop anyway.

Another advantage is that this clamp also gets rid of the offset of the signal amplifier.

An update on the progress of the new board. At this moment I am struggeling with the PLL, it has excessive jitter. I will keep you informed.

Was curious if this project is still active. Please send me a PM if I can help test in anyway. I would really like to get one of these.

Thanks,
Brian

Hey Beun, hows the circuit coming along or are you taking a breather from it. Kinda curious how its turning out.

I have been away for a while primarily caused by the joys of moving and unpacking boxes. As a pure coincidence, I have been thinking about getting back to this project, just because I am not letting myself get beat by some dumb circuit.

I should have time next week to get back working on this.

Hi Beun, Now thats the spirit, I've been there before. You just gotta keep at it and the answer will be starring you in the face before you know it.

Let me know how you make out.

Hi Beun,

Making any progress. I have another question, I know there are many different ways to do the conversion(opamp arrangement), I'm curious why you choose to make up the grn signal from the outputs of the RD and Blu opamps. It is adding the noise etc from the previous stages as opposed to other schemes which derive the RD and Blu from the R-Y and B-Y and Y stages directly.
Like I said I know there are many ways to do things, I was just wondering if you relized this and why you choose this topology.

Thanks

Count me out. This is behind me. time is a factor. After almost 2 years, it was time to move on.

Yeah, it's been awhile, but count me in if you want to finish it. I've been holding off getting an HD box from Comcast and just using a Fusion card for OTA channels until this can get finished. Would love it if you can figure this out so I don't have to spend hundreds of dollars on a commercial converter. Send me a PM if you want some help testing.

Thanks,
- Brian

Walter,

Progress is slow mainly caused by the desire to completely supress the sync and Art I understand you are bailing out, it is taking a very long time. From a technical point of view I am going to nix the PLL and directly create the sync suppression from the output of the sync separator, even if it means that there are going to be some ragged edges around the sync.

The reason to create the green from the red and blue is that otherwise I would be piling up errors. According to the color space conversion the green signal is a function of Y and R and B, therefore if I would have made a gain error in creating R and B than the gain error in green will track. If I would have made it direcly through a combination of Pr and Pb it would not track.

Hi Beun,

Keep at er. Yes I would nix the PLL and the pal or pic , use the 4511 and some oneshots to get the proper blanking you need. I've been looking at doing a transcoder myself, I've been conversing with Moome on a design for a HDMI/transcoder card for the Ampro to start with. I don't think I've convinced him yet on the need to strip the sync and have DC restoration, he's worried about costs, but my feeling is if you don't try to do the right things to start with nobody will be interested in it anyway. If not then it may as well just be a HDMI card only. I think I'll design my own circuit and have him include it on the Ampro board that he's doing. Although I think the chip we'll end up using for the HDMI interface will have a analog component input on it as well, but somehow I don't think it would be as good as an all analog transcoder, after all it will be A>D>A. I know his original DVI/Component input was for SD and didn't have sync stripping or DC restoration. Apparently a few people now have them for their NEC XG pjs so I guess we'll hear how good it does fairly soon.

If you want some help let me know I'll see what we can do together.
Email me or pm me.

Walter,

Unfortunately I cannot get rid of the PIC because I need to program the sync stripper through the serial interface. Luckily this is a solved problem and relatively simple. I also need to keep the PLD and I have to put in some more logic to count pulses. I thought about using one-shots but that has the major problem that they are onoly good for one timing.

I'll keep you informed.

Hi Beun,

Yes that is true about the oneshots. If you are ready have the problems for the stripping solved what problems are left to iron out.

Walter,

When the sync stripping is solved, all problems are solved. That was the last hurdle. It looks like I have made some significant progress today, at least in simulation, so I am going to see if I can make a small daughter board that I can attach to one of my previous attempts in order to prove the principle.

Great, let me know how it works out. What kind of problem are you having with the sync stripping pulse, timing, width control, stability?

Walter,

In the old way the problem was twofold.

1) The EL4511 sync-stripper has in its datasheet that there is a horizontal rate oscillator at a rate of 512 times the line frequency. That is true on average but when looking at the signal with a scope I see that the IC does pulse swallowing to accomplish this.

2) The PIC can only do timing at fourth of its clock frequency (in the old setup only 128 times the line frequency) and for some reason has a variable latency on its interrupt line. This latency issue I don't understand because according to the datasheet it shouldn't be there.

The result of this is that there is jitter on the width of the sync-cut pulse and there is jitter on the position. Therefore I need to make to sync-cut pulse wider than needed and that cuts into the picture.

The new scheme now uses a counter that runs on 256 times the line frequency (I may change this to the full 512 times) and does not have a latency issue so the sync-cut width should be constant (barring errors in the 512xline rate of cause). I will still have some positional jitter but should be minimal (only one clock pulse width) and not noticeable in the picture.

Hi Beun, It must have alot of jitter on the cut sync pulse if widening it cuts into the picture. A little jitter would be okay as long you cut the sync, but to jitter that much, whats that 1-2uS of jitter. Assuming HD I think the sync is about 2.5uS and the H blanking is 5uS, correct.

Walter,

I am afraid that the sync width is much smaller depending on the format. For a 480p signal the sync width is 2.2us wide but for a 1080i/720p signal it is just around 1us. Furthermore, the front porch for 1080i is only 600ns (and an even narrower 500ns for 480p) and the back porch is 2us. This means that it is fairly easy to cut of a piece of the end of the line.

If there is jitter on the timing than it will look jagged and the picture has to be stretched to obscure it. I am trying reduce this as much as possible.

Interesting, I'm sure when I scoped the HD signal the total H blanking was 5uS and the tri level sync was about 2 - 2.5 uS wide(neg and pos). Yes if there is jitter on the H sync out to the PJ then it will look jagged, but the strip pulse should affect anything providing its not going into the adjacent active line(s). If memory serves me correct standard NTSC has a 4.7uS H sync, correct.

Your value on standard 480i NTSC is correct. Below you will find a link to a Tektronics paper on video measurements, it gives all the width's that are relevant.

Tektronics PDF (http://www.tek.com/Measurement/App_Notes/25_16653/eng/25W_16653_0.pdf)

Okay, where can I get one of those VM5000HD's or better yet where can I get the money to get one of those because I'm sure they aren't cheap. Good reading, thanks for the link. But it would be nice to have access to one for a while or at least during testing and setup, do you have one.

Unfortunately I don't. I have a 300MHz scope that I use for measurements and I use the PC and Powerstrip to set up the correct timings.

Beun,

Why not just use a sync stripper like one of these rather than trying to go with the micro? It seems pretty straight forward...

http:///www.intersil.com/data/an/an9752.pdf

http://focus.ti.com/lit/an/sloa057/sloa057.pdf

I wasn't in on this discussion at all before but just read through the thread today. I think you are going to have too many problems with the uC (as you have already run into).

What were you using the PLD for? I know you already do your color conversion in analog form so were you just using the PLD for counting or something really simple?

If you are already using a CPLD on your board you could also try A>D>A and do the color conversion in the CPLD. This would allow you to get the conversion exact. I might actually play with this a little bit. There are plenty of A/D converters that will handle HD flawlessly.

I'm not really a video guy...I'm an RF guy so can anyone tell me if you would see any artifacts on the screen if you had an 8 bit A/D that was running above the Nyquist rate?

Steve

Hi Steve,

The problem with those is they only detect SD(bilevel) sync and not the HD(tri-level). Besides that most opamps with disable functions on them are too slow at turn off/turn on to capture the right time frame(H blank), it would work okay on SD because of the long H blank time but not on 1080i or even 720P would be pushing it.

Hi,

Been away from this thread for a long time. Good to see it has not died off.

I've seen the output of the first generation of Beun's transcoder, and in terms of color and picture quality, the output is very nice.

The colors seem a bit different from the output of my Key digital Transcoder, but I am not sure which is better or more correct.

I have yet to compare the output of my Dish 6000 RGB output transcoded verses the 6000 outputting component video directly. Need to reactivate Dish for that!

I did see the sawtooth on the left side of the picture due to the varying synching of the blanking on a line to line basis. Great to hear that you got that licked Beun.

Steve, on the digital processing of the color signal, I would imagine you need to sample aiming for greater than 100MHz bandwidth to be artifact free given that other transcoders that work in the analog domain have bandwidths north of that number in the quest for that perfect picture. This would mean sampling 200 megasamples/second or higher. Plus 8 bits would not be good enough, you would need higher bit counts to capture the gradations of color, at least on the Y component. You would need to sample the R-Y and B-Y signals as well, meaning 3 A/D converters at least. Does not sound cheap.

Steve,

The answers of Walter and Ken are correct. It is the tri level sync of much narrower width that is the main problem. The first issue is that the sync strippers that the links describe do not get rid of the positive going pulse and that one just beyond the left edge of the CRT will actually bloom into the picture. The negative going pulse you may be able to get rid of with some very fast electronics, but the circuits described are a bit finnicky.

I mainly use the PLD to encapsulate some wild logic and in the new design as a programmable down counter as well.

Going digital is a nice idea but as Ken already mentioned, it will be at the cost of very high speed and at least 10bits wide, doable but not cheap.

A quick update:

I have managed to cram everything I need into a super 22V10. So I now have the counter I need, the generation of the sync-cut pulse (presettable through dip-switches) and all other signals. I will now update the schematic and the PCB, lets see if I can get this done over the long weekend.

Sounds like you're making some good progress.

So far so good, I think I have finished the schematic, now the PCB

Update,

The new PCB should be finished. I will give it a final check and than it can go out for fabrication this week.

Does that mean there will be a transcoder to test in a few weeks ??
That would be great news !
Any idea of cost ? What about connectivity ?

Beun,

A fellow I know has been trying to feed an RGB signal from a Motorola HDD200 to a BARCO 700 unsuccessfully. The Barco is a 3 gun CRT front projector with a 37 Hz max. horizontal frequency. It has RGsB inputs and a separate sync input. He has tried just RGB, RGB with H and V sync combined fed into the Sync terminal. He's also tried splitting the Green lead to feed Gs and S on the monitor. The best he can get is a green screen when he parallels the H and V to S. Any ideas? BTW, I' would be happy to give you an unbiased and complete evaluation of your transcoder if you wish. I am in Maryland.

Hi Beun,

Well thats great news, I too am gaining ground on my design, its pretty well done now, it will be going on the same card as the HDMI/RGB that Moome is working on. It should be ready by the end of summer, at least for the Ampro guys anyway, I'm not sure when cards for other Pjs will be ready but probably not long after.

Walter

The version I am doing now is just for basic proof of concept. It has a YPrPb in and a RGBHV out on a VGA plug. It does positive or negative sync, but that is about it. When this works, and yes I sould be getting the prints back in about a week, I will design a new print with more connection options like component passthrough, BNC connectors and whatnot. I will also put in options like RGBHV, RGBs RGsB with positive and negative sync and such. I don't know yet in which combinations I will offer this. I guess it depends on the cost of doing all this.

Regarding the Barco, does that thing work at all? The 37(k?)Hz(?) (did you make a typo here?) max input means it can only do 480p or 540p/1080i, it is not fast enough for 720p (45KHz horizontal frequency). Also, you can not just parallel two output signals, I am pretty sure that the HDD200 will definately not like that.

he was told to parallel the H and V sync by the fellow who sold him the Barco. i told him that that was wrong but hell what do I know I've only been playing with this stuff for 50 years.

My projector, the DWIN HD700 says it is processing a 33.7 Hz Horizontal frequency at 60 Hz when I feed it the ouput of the HDD200 receiving a 1080i signal with the output set at 1080i. If I run a 480i SD NTSC 480i feed through my DWIN transcanner, I get a reading of 43.4 Hz at 60 Hz. The HD display is vertically compressed using the projector's adjustments and daved in a memory for that source. I have over 60 individual saved setups fordifferent inputs and conditions (aspect ratios, gain, brightness, gray scale and color temperature and several others). The projector belongs to a gentleman named Fred who frequents other AVS forums. His projector is a Barco 700 with an RGsB input. The HDD200 puts out RGB or RGBHV not RGsB. Any ideas?

This is not the first time I heard of combining the H and V to get a composite sync.

I also did the same to get more stable video for my old projector, an Electrohome ECP3500. As I remember, it has a better signal path for the combined sync which is input to the H input, and then separated internally, than for a separate horizontal to the H input and vertical to the V input. I believe the V input was an inferior circuit. I used a T-style BNC combiner, 2 inputs on either end and the output on the stub coming from the middle.

I don't think this should be a problem with source hardware with buffered outputs, and it worked fine with both my VGA video output of my HTPC and my Dish 6000 receiver's VGA output.

This should not be a problem with this transcoder as the outputs are buffered? I forget what the output stage looks like.

In regards to the HDD200, is that output set to GRBHV output on 5 connections or RGB, i.e. YPrPb component video out which uses the same 3 rca connections? If the component video mode is selected, you would get the green picture with sync combined as described. I got this from looking at the manual for the HDD200, not from actually using one.

Neil,

I think I have a preliminary board laying around that can convert the syncs for you. I will dig it up and send it when you are interested.

Beun,

Let me get a hold of the fellowwho contacted me about this problem. He lives in Canada I believe on the west coast. I'll send you a note or have him contact you directly.

Ken,

My understanding of the problem is that he could only get a green picture with the switch in one of the two directions. In the other direction he got nothing but non syncing jiberrish

Kim,
> you can not just parallel two output signals, I am pretty sure that the HDD200 will definately not like that. <

It depends on the output driver stages of the HDD200, and how it's buffered. Some devices will handle this just fine, but it's not correct. You really don't want to be doing sync mixing by feeding back into the output driver stages of your source device.

Art,
> His projector is a Barco 700 with an RGsB input. <

Barco made several different 700-series PJs, but if it's the BV 700 (BarcoVision), it actually has 4 input BNCs: R, G(s), B, and S. I.e., it accepts either a combined H+V sync on S, or Sync on Green (but not both at the same time). (Also, it has a 5th BNC for composite video in.) The Source Select determines how it interprets the Sync.

- Tim

Tim,

Indeed, most low impedance buffered outputs don't like to look into another low impedance buffered output. You can use a combiner network and when the input impedance of the input you want to drive is high it may actually work.

Unfortunately, when you want to combine H and V sync into one, the correct way to do it is to use a XOR function, just tying them together will get you a wired OR at best

I just read through the whole post and this looks very very promising. It will be of the highest quality i have seeen yet in this conversion. I can't wait to see the final project and i am looking forward to possibly building one myself or buying a parts and board package from beun. An updated partslist would be great with the updated schematic so i can go shopping. :)

Another thing, I have been digging around on the net for awhile and came across Ken Gasper's (mentioned earlier) schematic of his transcoder. Here is a link (attached) for you guys to look at and possibly get some ideas. i was going to build his but with the new discovery of this one i might have to wait.


Ryan O'Keeffe

PS: since i already have two of the max opamps in kens design, is there any compatability with those used in this circuit? just a thought.

Ryan,

Thanks for the link. I have seen these kinds of schematics before and it will most likely work for a standard definition XBOX converter. Unfortunately, the LM1881 does not do any high def resolutions and the circuit as a whole will not suppress the sync. For regular TV's this is usually not a problem but it not very elegant either.

The MAX4383 seems to be a good opamp, but the pinning is incompatible with the one I use (LT1399) and it doesn't have the disable that I use as well.

Hi Beun,

I really wonder if suppressing the sync is necessary, it won't affect the conversion, and it won't do anything once it gets into the PJ, except it will appear on the Green input causing the pj to sync to the grn, unless you can tell your PJ which signal to sync to this wouldn't matter. So unless you plan on shifting the H sync in the H blanking period I don't see any reason to strip it. The only problem I see is the PJ may not sync on the 1080p H sync because it may be too narrow.

THe MAX4383 will just barely do HD and it wouldn't be acceptable for 1080p.

Walter,

Because of the conversion from component to RGB, the sync not only appears on the Green signal but also on the Red and the Blue. As I understood is there are mainly two problems with the sync on these signals:

1) black level clamping can be compromized.
2) The positive going portion of the sync is fairly white and although it is off screen it can cause blooming into the left area of the screen.

Regarding the Maxim opamp, granted the LT1399 is much better (0.1db @150Mhz) but the Mixim isn't that bad although I would not use it.

Hi Beun,

Well I don't think it would cause any problems with the black level clamping, and causing blooming again I can't see that being a problem either. I thought this also for a long time too, now I answer this only because of the Pjs I have looked at, the schematics that is(Sony G90, G70, Ampro 3600, 4600, Barco 909/Cine 9, Electrohome Marquee) and all of these pjs accept sync on green, but none of them strip the sync off the grn signal before it reaches the tube, they tap the signal and feed it into the sync sep but they don't do anything after that. They all do the clamping with the sync present and each channel(R,G,B) all have the same clamping circuit for each channel, different makes of course each use their own style of clamping. So if leaving the sync on the grn was going to cause a problem I think they would have done something to strip it. I talked with tse (who works for VDC) about it and he said he sees no reason either why it would be need to be stripped.

I checked this out last night on my 3600 and scoped the sync going right to the final stages on the neckboard of the grn tube and there was no blooming on the screen, I only had the Y component connected to the GRN input, but it would be no different on the Blue or the RED if it had sync on them too.

Walter,

Well this is good and bad news. The good is that a circuit without sync removal is simplicity itself and can be derived from what I have in no time. It will also be a lot cheaper. The bad is all the time I have put in this :D

Did you try it with only negative going sync or also with tri-level sync?

Hi Beun,

What I did was just take the Y output of my NN208 player and connected it to the GRN input of my 3600. Then I switched it through the various formats SD, HD 1080i, 720P and 1080p. It wouldn't sync on 1080P, the only reason I can think of why it wouldn't is the neg going sync pulse for 1080p is only about 400nS wide and the sync circuits couldn't lock onto it, too narrow.

Yes you have put alot of time into your project, I've been putting a fair amount of time into my own version. Although mine is nothing like yours in its topology, I'm sure they will work equally well. The sync stripping part is not that difficult to do but it does add more circuitry and a nmos switch in the video path of each signal, although I switch only the Y component, the other two switches(R+B) are required to maintaine consistancy in phase delay and signal loss.

I'll have to do some playing with this on my 3600. The only problem I can see is leaving the sync in, is if you want it to sync on an adjustable sync via the TTL sync input and it prefers the GRN/sync. It would be easy for me to mod my 3600 to ignore the Gs if it goes that way. According to tse, he figured that the TTL input would overide the Gs but I haven't tried that yet. If I wasn't worried about doing 1080p I would just leave it, but I'm doing this in conjunction with Moome(I'm doing the transcoder and He's doing the HDMI section for a universal board for different PJs, although I won't be making any $ from it just a free board) because my 3600 won't do justice to a 1080p signal anyway. Considering most people have 8"ers and not 9"ers, it wouldn't bother too many I'm sure to go the easy way and not worry about 1080p. Although I suppose one could put a pulse stretcher(to 1uS) on the neg going portion and that would probably fix it, as most should be able to sync on a 1uS sync.

Hmm, after hearing this about the Max chip i am going to have to wait for beuns circuit. I want the conversion for the 1080i resolution so your chip will do a better job. The cost is also a concern athough not huge, all i am looking for is a good convertor for around 50 or less after i build it. Can't wait for the new circuit and keep up the good work.

I just saw the email that the boards have shipped, I guess I will get them on Thursday. Unfortunately I am away for the weekend but I have the evenings free the whole next week.

I am still in the group that says "sync removal from the color outputs is critical", for at least two reasons:

-Some projectors and maybe other display devices accept component and RGBHV through the same port, and auto-decide which format is input based on finding sync on the green signal (therefore it is assumed to be component).

-Some RGBHV video switchers cannot handle color signals if they have sync on them, or they will have black-level/clamping problems.

Walter,

> I really wonder if suppressing the sync is necessary, <

It is.

> it won't affect the conversion, <

It does.

> and it won't do anything once it gets into the PJ, <

The problems arise before it gets to the PJ.

> I don't see any reason to strip it <

Neither did the designers of the rev 2 Key Digital. They learned their lesson the hard way, and corrected it on the rev 3 unit (though their design still lets some sync spikes leak through, as Cary demonstrated).

Nor did the designer of the HD version of the Audio Authority transcoder. Which is why it was withdrawn from the market. Nor did the folks who made the VDIGI-Z3 (mainly for gaming), which is why there's a green cast over the image, which varies in intensity inversely proportional to the luma amplitude, and destroys black levels.

If clean stripping of tri-level sync wasn't so important, Beun wouldn't have spent so much time and effort on it. Ask Petr why he bothered with "complete synch tip removal" on his HDC transcoders, if there was no need for it. Ask Mike Parker, designer of the highest quality transcoder out there, how important sync-stripping is, and he'll tell you it's critical.

Improper, or incomplete HD sync stripping will result in a number of problems, all of which will degrade the PQ of the RGB output of the transcoder.

- Tim

Hi,

If the dc restore is done properly, removal of the sync shouldn't matter. And lets just say that it does matter, then all the PJ designers got it wrong because not one of them removes the sync. And if you don't believe me then have a look at the schematics of the G90,G70,Ampro x600, Marquee, Barco Cine 9 etc etc.

And please, tell me how it will affect the conversion. The sync pulses happen during a period when no conversion is necessary, unless you're using opamps with a very poor recovery time from fast rising pulses along with a poor dc restore circuit, then I could these things causing a problem. A poor dc restore circuit on any of the three components is going to cause a shift in brightness at times.

I don't want to argue with anyone on these points, I'm just pointing out what I see and along with other engineers with whom I've have conversations with about this.
Tim, do you have a electronics background, if so then maybe we can discuss this further off thread.

Thanks

Tim, Walter,


If there is a off thread discussion on this could I be included, not only do I find this extremely interesting since I am just developing this blindly as I don't have a CRT front projector but it also may effect the number of options I could include or exclude.

Hi Beun,

I don't mind discussing it here after all this is more of a technical thread anyway. Again I don't want to argue any of these points as I'm in the same boat as you. But the more I work on the design the more I find things like this out. The more technical people we can get into the discussion the better as I'd like to hear the technical side of why someone thinks it needs to be done a certain way. Now maybe if we could get Mike in on this to go over his findings as He's done a copy of revisions to his original design.

Thanks

Hi,

THe barco Cine9/909 PJ has a component (YPbPr) input,it wasn't until I got alook at these schematics that I thought it was necessary to remove the sync, so I started looking at all the rest and found the same thing, no sync removal. Looking over the schematics(909) starting at the component input and going right through to the tubes, no-where in the circuitry is there any circuit for stripping/blanking out the sync on the Y component. The Y component is spilt in the matrix(meaning the sync is put through to the RED and the BLUE) while still containing the sync and remains that way right to the tubes. THere are two separate clamp circuits(one set of circuits for each colour), one on the inputs board and one on the drivers board.

Unless of course I'm missing something here, which is entirely possible.

If anyone would like a copy of the schematics for those sections of the 909, PM me with your email.

Thanks

I just found an interesting tidbit on the Infocus website in the glossary of terms section


Color Red, Green, Blue & Composite Sync Outputs
Provides analog red, green, blue level. 7 volt P-P video output signals and negative-going 4 volts P-P non-terminated. and 2.3 volts P-P terminated TTL level composite sync output, matching the input standards of most data monitors and projectors. On the RGB-120 and RGB-202xi interfaces, sync is automatically stripped from any input computer signal that has sync included on the green channel. With sync on the green channel, some large screen data monitors and projectors may display a greenish tint, as well as a pulling to the right at the top or bottom. Stripping sync from the green video and using the separate sync output on those interfaces solves these problems. Sync can be added to the green channel by setting the "Sync On Green" switch.

A quick update on the progress: The new PCB is in and I have started to build it up. I had to order a few more parts that I had forgotton so in the meantime I can finish programming the PIC and the PLD. I will keep you informed.

Hi beun,

sounds great, let us know when you have some big news. Very exciting stuff happening here.

An update before I call it a night, this is only very preliminary since I still have a lot of testing and some additional programming of the PIC to do but:

IT SEEMS TO WORK

I can now set the position of the sync cut pulse by changing DIP switches, the black clamping works like a charm and I generate nice H and V sync pulses at the output.

I hate to leave you guys hanging like this but goodnight.

Congrats! That sounds like great progress.

- Tim

An update before I call it a night, this is only very preliminary since I still have a lot of testing and some additional programming of the PIC to do but:

IT SEEMS TO WORK

I can now set the position of the sync cut pulse by changing DIP switches, the black clamping works like a charm and I generate nice H and V sync pulses at the output.

I hate to leave you guys hanging like this but goodnight.
That is great news. Having been waiting years to try one of these out, please let me know when one is available for testing. I can compare it to two different Petr boxes, and have five or six HD component sources available.

When all goes well, I can start to send out a few boards as early as next week. I have 4 boards total, one of these is for me so I have 3 left to pass on.

When all goes well, I can start to send out a few boards as early as next week. I have 4 boards total, one of these is for me so I have 3 left to pass on.

Great news.

I have an older SA2000HD cable-box and a Barco 1208 if they are not represented in your tests. Be happy to volunteer to be a tester.

Joe L.

Hi Beun,

Good to hear things are moving along as planned.

More update,

I just got rid of some bugs in the microcontroller code and I am ready to try it out between the output of a DVD player and a VGA screen. I will keep you guys updated on the results.

Any chance you can test it with a game console? I guess it would have to be progressive scan though, like the xbox or a gamecube (if you hold down a button while booting up the gc).

This sounds interesting - maybe it will be a good alternative to the X2VGA+.

Unfortunately I don't have a game console, but it should do both progressive and interlaced although the color conversion is geared for HD and not SD.

Ah. Hmm, the color conversion geared for HD can be an issue if you're using a regular DVD player (480i or 480p). I can't remember which, but there can be significant green push when outputing one color space while the display is expecting another. This could get complicated. :)

480i output can be problematic for most computer monitors - any issues with that so far? I assume it is a display problem, not a transcoder problem!

Anyways, thanks for your time and effort - it is pretty darn cool.

Since I already did a transcoder with a selectable color matrix, I can do it again. In the end it is only a minor cost adder. You are right about the interlaced resolution though, it is a display problem and not a transcoder issue.

Max asked:
> Any chance you can test it with a game console? <

There are already a number of basic transcoders that are adequate for gaming purposes, and cheaper than this one will be. That's not its target domain at all.

> 480i output can be problematic for most computer monitors - any issues with that so far? I assume it is a display problem, <

So? No VGA-class computer monitor syncs down as low as 15 kHz. And none of us here cares about that at all. So there are no "issues" with it.

The primary design criteria of this transcoder is to convert 720p/1080i HD component video with tri-level sync to RGB video + bi-level syncs, in a quality fashion, at at economical price point. It will handle 480p as well, though without specific color-space conversion, but that's not a priority.

- Tim

From reading the first page, I had the impression this was a more general transcoder. I didn't find an easily accessible description of this device - much less a summary of goals or a "mission statement" defining the target.

The poster of this comment:

http://www.avsforum.com/avs-vb/showthread.php?p=2768660&&#post2768660

did mention he would like to see 480i support, among other things.

In short, calm down. :)

Just to list the original goals for this development

1) High quality transcoder from YPrPb -> RGBHV
2) Input compatible with at least 480p, 720p, 1080i
3) Color matrix was always intended to be HD (720p/1080i) only
4) Compatible with bi- and tri-level input sync
5) Complete removal of all H-sync both negative and positive going portions
6) Not too expensive

In addition there were discussions about additional goodies (this is from memory)

1) VGA passthrough switch
2) Drive two RGBHV outputs
3) Selection of RGBHV or RGBs or RGsB outputs
4) BNC connector option
5) Brightness and saturation controls
6) Horizontal shift control

From the goodies 1, 2, 3 and 4 are easy to do while 5 and 6 are harder to almost impossible and more expensive.

In adition I could also do:

1) Double conversion matrix, both for SD and HD
2) Remote control (lot of work to program and additional cost)

If anyone has more desires please vent them here.

Thank you very much beun for the clarification.

Hi,

According Mike Parker, who designed the MP5 which has the HD colour matrix, SD looked just fine on it.

Lets give a detailed update on the progress:

I did a thorough testing with a DVD player and a computer generated display through one of my regular transcoders on a LCD display. This went resonably well, unfortunately the LCD has some issues with the timing and it doesn't handle narrow H-sync pulses very well as they need to be fairly wide for the display to catch. I do have a very good CRT monitor but I have to dig that one up out of storage.

From what I was able to see I can report that the sync stripping works completely as intended. There is a minor amount of jaggedness like in the old one, but this is easily moved off screen. Additionally the width of sync stripping can be set by DIP switches to anyones liking.

I did see that I had some issues with the black level clamp under some conditions. I use the enable pin of a video opamp connected to the backporch output signal of the EL4511 sync separator to close the black level clamp loop. It appears that the disable time of the opamp is a bit too long when the backporch signal ends close to the start of the line creating some streaking on the display. This usually only appears to happen in bi-level sync mode as the EL4511 sync separator creates a much longer backporch pulse in that case. In tri-level sync everything seems to be OK.

I already know what to do about this and I will fix this in the production version.

That is great news !
So pre-production testers will be ready in days ? Weeks ?
I'm so itching to try this thing, its been a long time coming...
Any guesstimates on pricing ?

This is great that these will be coming out soon. I have a few questions while we wait regarding the applicability of these transcoders and terminology (I searched the forums for over an hour and found some answers, but not all):

From what I understand, connecting a Progressive Scan DVD Player (YPrPb, sync on Y, 3 RCAs) to an RGsB (VGA, HD15) accepting projector can just use a breakout cable and wouldn't need this adaptor. But what about connecting an HDTV component source? HDTV is YPrPb, tri level sync (sync on all signals). Are there HDTV boxes that output YPrPb, sync on Y? This would then require require tri-level to bi-level sync conversion, correct? How does sync stripping and the like relate to tri-level to bi-level sync conversion? What about the HDTV colorimetry matrix support, is this only required because of other conversions being involved?

Thanks

Lets see if I got the questions right.

Some projectors accept both RGB color coded signals with sync either separate (RGBHV), combined (RGBs) or with sync on green (RGsB) and YPrPb (component) color coded signals. For the YPrPb sync should be on all three signals and should also be tri-level for HD (720p and higher). Most consumer HD devices don't output sync on all three signals but only on Y.

Now if your projector understands component color space than you indeed only need a breakout cable for the connection from a progressive scan DVD player or any SD/HD source to your projector.

Even if the sync output of a source is tri-level, a good only bi-level projector should still be able to sync on it. In the eyes of the projector the tri-level sync pulse is just a bit narrower (around 400ns). If the projector requires a wider sync than you would need to do a tri- to bi-level conversion. It also should not matter that there is sync on the other signals, in the end they fall outside of the picture.

If the projector only understands RGB color space coded signals, that you will need a transcoder if the sources only output YPrPb.

Thanks for your answers, you did get all the questions right!

"Most consumer HD devices don't output sync on all three signals but only on Y."

This is good to know. Are there any drawbacks to this?

Quoting http://www.extron.com/technology/archive.asp?id=ta062002

Tri-level sync was introduced with the SMPTE 240 analog HDTV standard. Previous to that, the early HDTV 1125/60 systems used various synchronization waveforms, as provided by various 1125/60 equipment manufacturers. The creators of the later SMPTE 240 HDTV standard searched for a standard sync waveform that would ensure system compatibility. The goal was to provide more precise synchronization and relative timing of the three component video signals. HDTV component video has sync present on all three channels: Y, Pb, and Pr. In addition, the sync structure needs to be resilient enough to endure multigenerational recording and other noisy situations. Tri-level sync met the requirements.

...

[It's] symmetry of design results in a net DC value of zero volts. This is one major advantage of tri-level sync. This solves the problem of a bi-level signal introducing a DC component into the video signal. The elimination of DC offset makes signal processing easier. Within our new digital television system, the unique excursions of the sync derive numerical values that are easily coded and easily recognized within the digital transmission channel.

So the elimination of DC offset with tri-level sync makes signal processing easier. Does this improvement carry any practical benefit on to the consumer, or is it just making manufacturing and compatibility costs less for the industry? Are consumers losing anything by having HDTV boxes that output bi-level sync instead of the SMPTE 240 standard tri-level sync?

This Extron article is interesting, although I don't quite understand the reasoning. Video itself is already a signal with a non-zero DC content, the presence of a bi- or tri-level sync doesn't change this.

From a consumer point of view I don't think it makes any difference, this is for manufacturers only.

Hi,

Yea I've read that piece before and I'm not sure I understand the real advantage of the change(bi to tri) either from a standpoint of eliminating the DC offset.

If you could include me on your test list for this, I'd be very grateful. I've been holding out for over a year in hopes that this would come to life.

- Brian

Hi Brian,

Well at the moment Beun, Bill Blue and myself are designing a new transcoder so I don't know if Beun will be building anymore of the present ones, at least for now anyway.

I sent out 3 to be looked at, one already seems to be lost in the mail so unless I order a few new boards it will take a little while till the final design shows up.

Beun, care to share the most recent schematics and PIC/PLD code? I could use a couple of good, basic transcoders and am not avers to soldering.

Beun/Walter, will the new design be public?

Hi,

Yes the boards will be available from Beun and possibly some components as well. Whether the code for the pic/pld will be I don't know as thats Beun's property. As far as making just the schematics available without buying a board etc. that has not been discussed yet. There's no time frame as of yet as to when it will be ready as we're going to make sure thats there's no flaws in the design before its available of course.

I've got the wherwithal to fab and stuff boards, so that's not much of a concern should the design be released. If the design is not released (no harm no foul if this is the case,) I'd love for bare boards to be available.
If the PLD and PIC are not released in sourcecode (again, no harm) then a "buy a pic" option would be needed for stuffers such as myself.

I've got some experience sourcing boards (see tse's gamma circuit thread) and can recommend the same fabbers as in that thread.
I'd like to be able to offer up the services of my own production facility, but they are not interested in the volumes likely to arise (minimum they'll consider is short runs of hundreds at a time with thousands/year commitment.)

Hi,

Actually the person to talk to is Beun about that. I'm just in it for the design team and to lend my ideas/knowledge etc. Of course I'll be building up one or two to fit in the spare slots of my 3600, but it will be Beun who will be doing the board orders and making the kits available in whatever form he feels like offering them in.
This project was started just to build a better mouse trap so to speak than whats available commercially and make a top notch transcoder available to everyone for an affordable price, but basically to those who could populate the boards(soldering etc) and source/buy the majority of the components themselves. What components ie; part #s, where to buy them etc will be given and I believe Beun will provide preprogrammed Pic's and PLD's. But I'm not sure just how much he is willing to do as far as stuffing etc goes, I can't speak for him on that one.

Hi,

Actually the person to talk to is Beun about that. I'm just in it for the design team and to lend my ideas/knowledge etc. Of course I'll be building up one or two to fit in the spare slots of my 3600, but it will be Beun who will be doing the board orders and making the kits available in whatever form he feels like offering them in.
This project was started just to build a better mouse trap so to speak than whats available commercially and make a top notch transcoder available to everyone for an affordable price, but basically to those who could populate the boards(soldering etc) and source/buy the majority of the components themselves. What components ie; part #s, where to buy them etc will be given and I believe Beun will provide preprogrammed Pic's and PLD's. But I'm not sure just how much he is willing to do as far as stuffing etc goes, I can't speak for him on that one.

Sounds perfect for my needs. I'll wait with baited breath to see this through.

jtnfoley,


Give me some time to scrape together all the information, I have no problem with posting the current schematic and the source code for the PIC and the PLD. I will also publish a list of the deficiencies that the current solution has.


Kim

Just to list the original goals for this development

1) High quality transcoder from YPrPb -> RGBHV
2) Input compatible with at least 480p, 720p, 1080i
3) Color matrix was always intended to be HD (720p/1080i) only
4) Compatible with bi- and tri-level input sync
5) Complete removal of all H-sync both negative and positive going portions
6) Not too expensive

In addition there were discussions about additional goodies (this is from memory)

1) VGA passthrough switch
2) Drive two RGBHV outputs
3) Selection of RGBHV or RGBs or RGsB outputs
4) BNC connector option
5) Brightness and saturation controls
6) Horizontal shift control

From the goodies 1, 2, 3 and 4 are easy to do while 5 and 6 are harder to almost impossible and more expensive.

In adition I could also do:

1) Double conversion matrix, both for SD and HD
2) Remote control (lot of work to program and additional cost)

If anyone has more desires please vent them here.

Would it be possible to add an SDI output? This would enable this to be used with a Blackmagic type of HD-SDI capture card...

Thanks

dvgeek, there's already been 22 months of feature creep on this effort. I don't want to overstep my bounds and make statements on behalf of Buen and Walter, but... If this feature is important enough you should probably look at the existing design (when released) and come to the table with suggestions WRT likely interface devices, example circuits, whitepapers, etc.

Hi,

There has been no talk of SDI in this project thus far and I don't think there will be any, this is going to be based around a transcoder and thats it.

I agree, A SDI output is a whole different ballgame, the input is analog and SDI is digital, this would mean A/D conversion and probably digital processing. An interesting project on its own but well ouside of the scope of this project.


Kim

I agree, A SDI output is a whole different ballgame, the input is analog and SDI is digital, this would mean A/D conversion and probably digital processing. An interesting project on its own but well ouside of the scope of this project.


Kim

WTS / jtnfoley / beun

You are all right - its too late for a feature request at this stage - it was just wishful thinking on my part - sorry...

And thanks for taking the effort to reply - really appreciate it.

What is the status of this project?

I am not technically inclined. I do not understand all the technological aspects of this message thread. I just have a simple question I need answered.

When DirecTV replaces my DTC-100 with a new MPEG 4 receiver, I will lose the VGA output which I need to connect to my RCA MM36100 monitor. At that point, I will need to purchase a component to VGA transcoder. So far I have found three possibilities:

http://www.vdigi.com/index.php?option=com_phpshop&page=shop.browse&category_id=759df22fdaeabe0bcd58c745d6286257

or

http://www.lik-sang.com/info.php?category=53&products_id=4233&

or

the transcoder that is being created by the person who started this thread.


How much will this thread's transcoder cost? When will it be available? What will make it superior to the other two options listed above?

Thank you,
Stu

What is the status of this project?

I am not technically inclined. I do not understand all the technological aspects of this message thread. I just have a simple question I need answered.

When DirecTV replaces my DTC-100 with a new MPEG 4 receiver, I will lose the VGA output which I need to connect to my RCA MM36100 monitor. At that point, I will need to purchase a component to VGA transcoder. So far I have found three possibilities:

http://www.vdigi.com/index.php?option=com_phpshop&page=shop.browse&category_id=759df22fdaeabe0bcd58c745d6286257

or

http://www.lik-sang.com/info.php?category=53&products_id=4233&

or

the transcoder that is being created by the person who started this thread.


How much will this thread's transcoder cost? When will it be available? What will make it superior to the other two options listed above?

Thank you,
Stu


There's another option in the works... look for "moome external"

I am finishing up the final version and should have initial production ready early next January, my biggest issue at the moment being in which case I am going to put it.


Kim

Hi Kim,

Which one would that be.

I am finishing up the final version and should have initial production ready early next January, my biggest issue at the moment being in which case I am going to put it.


Kim

I have been following this thread with anticipation as I am in need of a quality transcoder. This whole thread brought me back to my days as an EE student. Are there any new developments on this Buen?

Hi Garrett,

We're working on it still, I'm sure Kim will let everyone know as soon as its ready.

The board is ready and looks good to me, I have send one to WTS a few days ago so he can have a look at it as well. I have made my choice on the case and I should get two of them in today. I can than start on the customization (having a few holes drilled and some silkscreening) and have them manufactured.

All in all it is still moving along.

The board is ready and looks good to me, I have send one to WTS a few days ago so he can have a look at it as well. I have made my choice on the case and I should get two of them in today. I can than start on the customization (having a few holes drilled and some silkscreening) and have them manufactured.

All in all it is still moving along.


Thanks for taking the time to update Buen and WTS! I'm sure I speak for many here when I say we are looking forward to playing with the design. :D

OK, now I need it too!!

Any progress?

Thanks.

Hi,

Well I can say that for the price which Kim has told me(just recently) IT'S A STEAL. I have only tested/tryed 3 different transcoders including this one and the one which is internal to my Zenith Pro1200x(Barco Cine 8 Onyx) CRT projector and I can tell you this one wins by a mile, hands down.

Hi,

Well I can say that for the price which Kim has told me(just recently) IT'S A STEAL. I have only tested/tryed 3 different transcoders including this one and the one which is internal to my Zenith Pro1200x(Barco Cine 8 Onyx) CRT projector and I can tell you this one wins by a mile, hands down.

Sounds great. So...when will it be available?

Hi,

Well you'll have to ask Kim that question, last I talked with him he was in Germany on business, but I'm sure he'll answer you as soon as he can.

Like I said before, from a technical point it is finished, board, case and everything. I got the quotes in for the case modification and am pondering on the cost of the initial investment I have to make. If I can get a better feeling for the demand I can make the decision to pull the trigger or not.


Kim

Like I said before, from a technical point it is finished, board, case and everything. I got the quotes in for the case modification and am pondering on the cost of the initial investment I have to make. If I can get a better feeling for the demand I can make the decision to pull the trigger or not.


Kim


Thanks Kim, makes sense. So.. do we need a poll or something?

We may although I am not quite sure if it is allowed according to forum rules.

Hi,

Why not, I see they were doing it for a board they(the crt guys) wanted moome to build for their NEC switchers. Go for it.

Hi,

Why not, I see they were doing it for a board they(the crt guys) wanted moome to build for their NEC switchers. Go for it.

OK, posted, hopefully I am not in trouble after posting this :D

It is here guys:
http://www.avsforum.com/avs-vb/showthread.php?t=651255

OK,

I just put in the order for the case modification, lets see if they can do this right the first time. It is probably going to take 4 weeks until delivery.


Kim

Hope you will save one for me KIm. Art Neill

MrHiFi wrote:
> Hope you will save one for me KIm. <

Nope. ;) Your name was added to the blacklist last June, Art, when you got frustrated and wrote:
> Count me out. This is behind me. time is a factor. After almost 2 years, it was time to move on. <

No soup for you. :D

- Tim

Can I ask a quick question? I've read this thread many times, and I even understand a wee bit of what you guys are talking about...

Both myself and at least one other person have a unique issue w/a particular HD source device and our older Toshiba HDTVs -- a severely floating black level w/the 1080i component output of a DirecTv HD DVR (HR10-250). Same problem w/it's 480p output initially, although I was able to correct that w/a service mode adjustment in display. No problems w/1080i (or 480p) from another other source, including other HDTV receivers, just this particular HD device. There is no color shift evident, only a black level that floats w/APL.

Is this most likely an issue w/sync pulse widths, ac vs dc coupling, Pr/Pb sync stripping, or something else?

Thanks,
Steve

Steve,

It is probably a problem with the black level clamp and sync separator of your Toshiba HDTV. For some reason the 1080i signal has an extremely narrow backporch (even narrower than that of 720p in spite of the 720p's higher line frequency) in which you can do the black level clamping. So when your black level changes with picture brightness it is probably partly sampling the beginning of the line as well.

Additionally the width and position of the black level sampling pulse usually depends on the width of the incoming sync, so when the sync coming out of your particular HD source is different than what the Toshiba expects, or is non-standard in itself like bi-level instead of tri-level, I can definately see it going wrong. Video inputs are always assumed to be AC coupled so black level clamping is a must and the sync, even if it gets to the picture tubes (I assume it is a CRT) should not have any effect on the blacklevel (negative going sync actually helps).


Kim

Yea... what he said. :)

Hi Steve,

Running your signal into a tcoder like Kim's should fix the problem because like Kim said all the inputs are AC coupled including Kim's. Going through Kim's tcoder will reestablish the correct blacklevel because it has proper dc restoration on board.

Steve,
I have the same problem with an LG LST3410A sending an RGBHV signal to a DWIN HD700 CRT Front projector. Other input sources work perfectly. The innards of the DWIN are Toshiba components so it is quite likely that the reason we both experience the problem is due to the common ancestry. I have tried several transcoders including one that cost over $300.00 and whose designer claimed it would solve the black level variation problem. It did not. I mentioned this issue to Kim some time ago and apparently he has addressed it in his design. Please let me know if it works for you since Kim has "blacklisted" (his word not mine) me and refuses to sell me a unit. I offered to test the unit for Kim many times but I was never given the opportunity. I sincerely hope it works on your set as that gives me hope thatthere is an ultimate solution for my black level variation issue.

Art,

I don't remember ever "blacklisting" you and I definately never refused to sell you a unit. Heck, if I had one finished at the moment I would send it to you to take a look at.

Are you sure we are talking about the same Kim here :confused: ?


Kim

Art,

I don't remember ever "blacklisting" you and I definately never refused to sell you a unit. Heck, if I had one finished at the moment I would send it to you to take a look at.

Are you sure we are talking about the same Kim here :confused: ?


Kim

Maybe he's referring to this post?

MrHiFi wrote:
> Hope you will save one for me KIm. <

Nope. ;) Your name was added to the blacklist last June, Art, when you got frustrated and wrote:
> Count me out. This is behind me. time is a factor. After almost 2 years, it was time to move on. <

No soup for you. :D

- Tim

AFAIK, Tim != Kim. And, besides, that does look like a winking smile.

Are you not TIM? Perhaps not but then who is Tim? Well now i am really confused. I believe my position is clear and always has been. I supported and encouraged your development of the device ever since the beginning when I gave suggestions and offered to test your device as I had several others. We even exchanged private communications. After a while, I assumed you had stopped work on the project and wanted to make clear that I would not be waiting for its development. When i saw your posting indicating that you were close to completion, I offered once again to buy one. Out of the blue you posted the reply in the prior comment which I will not repeat again. I believe you need to make your position clear because clients do not hang around forever. This client is willing to forgive and forget but please some clarification is in order. If you want to sell me a unit, I am here with cash. Please let me know.

Art inquired:
> Are you not TIM? Perhaps not but then who is Tim? <

That's me. And, no, Kim/Beun/Texas/700+ posts <> Tim/VideoGrabber/Michigan/2200+ posts. We don't even bear a family resemblance. ;) I've been a Forum member for several years longer than Kim, if (based on the tone and implication of your comments) you're accusing us of being the same person under different handles. Not the case.

> Well now i am really confused. <

No doubt about that. I thought my post was pretty clearly a joke. (BTW, the "No soup for you" was a Seinfeldianism.) Evidently the winks and grins were too subtle. Sorry to send you into such a tizzy.

> Out of the blue you posted the reply in the prior comment which I will not repeat again. <

He did no such thing.

> This client is willing to forgive and forget but... <

Forgive what?. :confused: Kim has done nothing to apologize for. Bizarre, just bizarre.

- Tim

Quote:
Originally Posted by VideoGrabber
MrHiFi wrote:
> Hope you will save one for me KIm. <

Nope. Your name was added to the blacklist last June, Art, when you got frustrated and wrote:
> Count me out. This is behind me. time is a factor. After almost 2 years, it was time to move on. <

No soup for you.

- Tim

I believe this is what we call "sarcasm"... especially when you put in context your own words from ealier post. That makes your current plea "ironic".

The "no soup for you" pretty much clarifies this point. It's a line from Sienfeld.

And now... Kim himself explains he had no "blacklist" and would gladly sell you a unit - yet you are still in doubt?

What word would best describe you at the moment ... hmmm. :)

Art,


A few others beat me to an answer so some of the text below is already a bit outdated.

I am still confused about mixing me up, Kim with handle beun, with Tim with handle VideoGrabber but I don't think that's the issue here so lets not talk about that.

I have always paid attention to your input and I think that the inputs you gave will be found back in the final product. I have never put you on any "blacklist" nor said I did (the posting you probably refer to did not originate from me and was meant as a joke anyway) and I hope you haven't done it to me. I also have no problem with you not waiting for the final result because honestly it took a very long time to complete and during that time I did give up for a while. In the end, this is just a hobby for me and I don't sell them to make a profit but just because I like doing it, I am a geeky designer at heart.

This end product from a circuit point of view is quite different from the postings you have all seen so far but the final result is exactly what was discussed. I dropped the ball on the last PM you sent me but I will correct that.

The current state is that I am waiting on a new quote for the case so I can send a PO and have the case customized. After ordering the case it should take around 4 weeks before I can start to put them together.

So when your black level changes with picture brightness it is probably partly sampling the beginning of the line as well.
Yep, that's exactly what's happening. I can even see that the frequency and magnitude of the brightness flucuations are triggered by bright objects entering and leaving the bottom left (I think) area of the raster. For 480p, I also had to open up the T&B blanking in addition to adjusting the 480p SCP service mode param (which I assume contropls where in the signal it looks for the pulses) to completely resolve it. Unfortunately, no go for 1080i.

I have the same problem with an LG LST3410A sending an RGBHV signal to a DWIN HD700 CRT Front projector. Other input sources work perfectly. The innards of the DWIN are Toshiba components so it is quite likely that the reason we both experience the problem is due to the common ancestry. I have tried several transcoders including one that cost over $300.00 and whose designer claimed it would solve the black level variation problem. It did not.
Your posts were how I found this thread and describe my exact problem too. Did you try this: HDTV switch & amp with DC restoration (http://www.video-storm.com/proddetail.asp?prod=CSW62). $160 and has 2 component outputs, one dc-coupled and the other ac-coupled, and also claims:

CSW62 contains an active DC level restoration circuit. In fact, this product is the only affordable switch on the market to employ this high end technology! The circuit will restore the DC levels on the output video to the proper specification levels regardless of what is present on the input.


Running your signal into a tcoder like Kim's should fix the problem because like Kim said all the inputs are AC coupled including Kim's. Going through Kim's tcoder will reestablish the correct blacklevel because it has proper dc restoration on board.
Excellent. I have a 2nd unit that came today to try, but doubt it will be any different since others have exact same issue w/similar age Toshibas.

How do I sign up for one of these Kim?

Kim-

Do you still intend to have loose boards/kits of parts available for this device? Thanks.

Chris,

Yes, I will still have boards and the difficult to get or specific parts available. The simple resistors and caps can be bought from Digikey.


Kim

Thanks Beun,

I will be looking forward to the transcoder.

Running your signal into a tcoder like Kim's should fix the problem because like Kim said all the inputs are AC coupled including Kim's. Going through Kim's tcoder will reestablish the correct blacklevel because it has proper dc restoration on board.

Wait a minute... isn't this a component-->VGA transcoder? I don't have a VGA input on my set, only component. I guess I need a component-->component transcoder, which is a bit of a oxymoron isn't it?

I do have an old AA VGA-->component transcoder though. I wonder if that would work: HR10-250 component--->Kim's device VGA--->AA 9A60 component--->Toshiba TV?

Stephen,

You could, but it wouldn't really improve things. Anyway, if you cannot disable the (faulty) black level clamping in your TV set, it won't make much a difference anyway.


Kim

Art,

Give me a few days, I need to put one together.


Kim

Steve,

It is probably a problem with the black level clamp and sync separator of your Toshiba HDTV. For some reason the 1080i signal has an extremely narrow backporch (even narrower than that of 720p in spite of the 720p's higher line frequency) in which you can do the black level clamping. So when your black level changes with picture brightness it is probably partly sampling the beginning of the line as well.

Additionally the width and position of the black level sampling pulse usually depends on the width of the incoming sync, so when the sync coming out of your particular HD source is different than what the Toshiba expects, or is non-standard in itself like bi-level instead of tri-level, I can definately see it going wrong. Video inputs are always assumed to be AC coupled so black level clamping is a must and the sync, even if it gets to the picture tubes (I assume it is a CRT) should not have any effect on the blacklevel (negative going sync actually helps).

Kim

Well I figured out the problem b/t my early-gen Toshiba HDTV and the HR10-250... the HR10-250 has an extremely narrow back porch (as you said), but it's much narrower than other 1080i sources. This was causing the black stretch circuit in my TV to go haywire. I flipped a few bits in the service menu and disabled this circuit altogether. And problem solved.

Could you post the final schematics for this project?

Stephen,

What Tweaks did you make? Perhaps i can find them on my DWIN HD700.

Stephen,

What Tweaks did you make? Perhaps i can find them on my DWIN HD700.

In my set's designer menu, I changed EHB2 and HBS2 (1080i theater and 1080i normal) params from hex(08) to hex(04).

My set has a hidden service menu w/some params, a super-hidden "designer" menu w/a lot more params, and then a super-duper hidden "register" menu w/the complete i2c control params. I maintain a comprehensive spreadsheet of all these menu and what the params do here that might help you find these params in your set: http://www.imagesoftcorp.com/X81Designer.zip

Steve

Beun,

I am posting this here because I feel that everyone needs to know what a great job you have done with the YPrPb to VGA transcoder. I've been evaluating it for 2 days and I am happy to report, it works perfectly. Not only does it accurately change the YPrPb signal to VGA but in my case , it resolves the brightness level shift issue completely. After evaluating and being disappointed with the performance of 3 other transcoders, I am pleased to report that yours provides a 100% perfect transfer.

To evaluate the device I plugged in my LG3410A which has both YPrPb and VGA outputs. I compared the two outputs with a variety of of material. The output of the transcoder is displayed on a 120" diagonal screen by a 3 gun CRT front projector, DWIN HD700. I watched 1080i, 720P and 480P and was equally impressed at all three resolutions.

Beun, you can be proud of yourself. You transcoder works perfectly.

I do have one recommendation. HaHa!!! You need some standoffs at the VGA connectors so that the 15 pin can be secured with screws. I know that is ridiculous but frankly everything els works perfectly and looks perfect. The layout is efficient and practical. I would think a small box would work well.

Let me know what you would like me to do with the prototype. I will buy it from you or whatever you wish. Thanks again. YOU DID IT!!!!!!!!!!!!!!1

Art,

Which three transcoders are you talking about? I could guess, but I'd like to know.

Thanks,
-Mike

Art,

The finished boxed transcoder will have the standoffs. This was just a bare test board.

As an update, I put in the final PO for the case modification last Thursday, I should get cases back in three weeks.


Kim

http://www.dcslinks.com/catalog/product_info.php?products_id=452

<http://www.digitalconnection.com/Products/Video/kdctca3.asp>?

http://www.zektor.com/hds4/index.htm

I tried these.

Art commented:
> After evaluating and being disappointed with the performance of 3 other transcoders <

> I tried these... http://www.zektor.com/hds4/index.htm <

Since that's a passive switch, with no processing at all, it's not surprising. It's not a transcoder.

- Tim

I was hoping for a comparison between Petr's transcoder, which I've owned, Mike Parker's transcoder, and Kim's.

-Mike

I purchased and returned a transcoder from a Canadian fellow. it cost over $300.00 and did not work well with my projector. The real difference with Kim's unit is how the brightness level is maintained constant and the color rendition exactly matched the input. Also on at least 2 of the other units, there was some horizntal displacement in the top 10% of the picture. Not with KIM's.

Art,

Did you get my PM on the horizontal shift? Does it work?

Beun,
I did what you said in this order. I transferred JP5 to JP6. Unfortunately, the sync went crazy. I tried removing JP7 but then I lost everything syncwise. I returned everything to its original location and everything worked like it did originally..

BTw, this displacement issue is not unique to connections through your transcoder. There are vast differences in the amount of horizontal offset I must apply to the RCA DTC-100 and dthe LG LST-3410A's. One reqires a setting on my projector of 76 while the other reuires 93. At 100 I could not get the unit that normally requies 93 to completely center. Filling the screen is no problem.

Unfortunately, my life is getting in the way of my fun. I must travel to FL until after 4/20/2006. I will play more when I get back. Right now i am trying to get ready and can notgive this the amount of time I should. I am sorry but i wil address it when i get back.

Art

Art,

You may have to turn the pots in order to dial in the H-sync you need. Both pots all the way counter-clockwise (it's a twelve turn if I am not mistaken) will give you no delay and the minimum H-sync width. Turning clockwise will make both H-sync wider and the delay longer.


Kim

An update, the cases are in the silkscreen process right now and should be finished next week.


Kim

The latest update, the cases are in and I expect to ship the first units in the first week of June.

The latest update, the cases are in and I expect to ship the first units in the first week of June.

Great news Kim, will you be taking orders today on your web? Gotta head out for work right now, but count me in for one unit :D

Regards, smurfer/nimo

Here's a link (http://www.crescendo-systems.com/rev_transcoder.html) to the preorder for the RTC2000 YPrPb to VGA Transcoder.

It's listed at $139.

Hi Kim,

Glad to hear you got it all done and will be shipping them soon, good job.

Yes, definitely. Congratulations, and kudos on what looks like a very flexible design, with lots of adjustability to handle any scenario. Kudos!

I think this will be a great solution for a lot of people with RGB displays.

- Tim

P.S. What did the bandwidth wind up at, in process and passthrough modes?

Tim,

The transcoding bandwidth is larger than 70MHz and the passthrough bandwidth is larger than 300MHz.


Kim

UPDATE

The boards are in and I already built and tested two. They look good so I will start shipping tomorrow. I can finish about two boards per day and four per day on the weekends so it will take me about a week to finish them all. All boards will be shipped on the principle of first come first serve.

I don't have a manual yet, I am still working on it and I expect to have something finished in two weeks.

Will you continue to sell the transcoders after your initial builds? That is, will I be able to purchase one at a later date? I ask because I'll be out of the country for a couple months and have no use for such a beauty during that period of time... : (

Regardless, congratulations on your achievement!

The transcoder will still be available after the first built as a regular item, so order anytime you like.

I received mine today.

Excellent unit and great performance.

I connected it between my LG LGA-531 DVD player (which has user settable resolution on the component output) and my Electrohome projector. The projector is happiest at 720p so that is where I set the player. I got the RTC2000 and the LGA-531 to replace my recently deceased 3dfusion/Mpact card (which I loved) that has lived in an old P233 PC since 1999. The 531 thru the RTC2000 appears to be at least the equal of the MPACT and should serve me well until I feel the need to change projectors and interfaces. I still need to tune the setup (using Video Essentials) but it looks real good as is.

The RTC2000 worked in its automatic modes flawlessly out of the box. The spare VGA input is now fed by my RCA DTC100 HD receiver and the high quality automatic VGA switch that was handling the PC and HD receiver VGA is at least temporarily put away.

Thanks Kim, and those that helped with the evolution of this product.

Walter

I'm woefully out of my league even posting here, but I'm going to ask a dumb question anyway. I was looking at the PDF for the final product and it sounds like it is designed primarily with stand 4:3 monitors in mind. I'm just wondering how it likes widescreen monitors (I have a Dell 24" widescreen...which, just to complicate things further is 16:10 instead of 16:9 :rolleyes: ).

Thanks!

It is actually designed with no particular resolution in mind, it is actually resolution in = resolution out within the confines of the supported resolutions. Your 16:10 Dell will just scale the video on its own (I guess you have the 2405FPW) to its native resolution which is higher than any defined video format.


Kim

I'm an EE student and would love to build this component to vga transcoder. I'm just getting into crt projectors but the problem is my devices (xbox, gamecube, etc) only have component out. Is there any chance of releasing a schematic so that I could build this thing myself? I know this thing has undergone several revisions and I'm not sure if the older schematics proved successful. My PJ is a Sony 1252q if that matters. Another thing is the sync stripper using the PIC. It would be nice to get that code. Maybe Beun could release a "lite" version of this project so people like me could take a go at it? Thanks Beun and others for all the hard work and maybe it's possible for you to share some of your knowledge to the next generation!

-Marc

I'm an EE student and would love to build this component to vga transcoder. I'm just getting into crt projectors but the problem is my devices (xbox, gamecube, etc) only have component out. Is there any chance of releasing a schematic so that I could build this thing myself? I know this thing has undergone several revisions and I'm not sure if the older schematics proved successful. My PJ is a Sony 1252q if that matters. Another thing is the sync stripper using the PIC. It would be nice to get that code. Maybe Beun could release a "lite" version of this project so people like me could take a go at it? Thanks Beun and others for all the hard work and maybe it's possible for you to share some of your knowledge to the next generation!

-Marc

Why don't you give the National Semiconductor LM1251 a try? It, and the matching RGB buffer, can be had in sample quantities (I got three of each) for about $20, delivered. As I have been to busy to live lately, I gave my parts to another member in the hopes that he'll do something worthwhile with them.

If you DO do something with the 1251, I'd be interested in seeing it (I was shooting for something small enough to package "daughterboard" style on the input cards of an NEC ISS 6010 switcher.

Will this allow me to connect my PS2 (Slimline version) to my Hyundai L90D+ computer monitor? It seems to do the same thing as the X2VGA2... but they say that you cannot connect the PS2 with the X2VGA2 because it only outputs 480i and the LCD monitor doesn't like that. In the DVD options on my PS2, I can change the output to progressive, but I don't know if that works with games as well.

Why don't you give the National Semiconductor LM1251 a try? It, and the matching RGB buffer, can be had in sample quantities (I got three of each) for about $20, delivered. As I have been to busy to live lately, I gave my parts to another member in the hopes that he'll do something worthwhile with them.

If you DO do something with the 1251, I'd be interested in seeing it (I was shooting for something small enough to package "daughterboard" style on the input cards of an NEC ISS 6010 switcher.

I will take a go at it! However, I went to the National website and I don't see the LM1251 to sample. Could you provide links to a datasheet + sample? That would be a big help if you have time, otherwise I will continue to search.

Just to let you know I have a Sony 1031q as well as a 1252q's to test this stuff on.

Ok I found out the chip is the LMH1251, not just LM1251

Looking at the datasheet...this sounds way too perfect...going to sample some of these chips and see what happens. Will post results as well once I get em. Stay tuned :D

Don't forget the RGB buffer, I forget the P/N...

Don't forget the RGB buffer, I forget the P/N...

hehe, I knew I'd forget something. Please let me know if I forget anything else. I will post a schematic of what I'm planning on doing and hopefully someone can double check me. I just ordered samples of the LTH1251 so now I will go and see what I need to do the RGB buffering...

hehe, I knew I'd forget something. Please let me know if I forget anything else. I will post a schematic of what I'm planning on doing and hopefully someone can double check me. I just ordered samples of the LTH1251 so now I will go and see what I need to do the RGB buffering...

I ordered samples of both the RGB buffer (LMH6739) and the converter (LMH1251). What I'm planning on doing is this:

Use the LMH1251 to convert from component to RGBHV, then buffer all five of the RGB signals. I will order the resistors, capacitors, and hardware from digikey or some place now. Someone please let me know if I'm forgetting something or if I don't need to buffer the last two connectors of RGBHV (does the HV need buffering? I'll do it just to be sure).

I guess one downside is that I'll need two power supplies since one of them likes 10V while the other likes 5V. For now I'll just have to use two dedicated power supplies. In the future is it better to use just the 10V and then you can build a little circuit to get 5V? My concern is ripple though.

Thanks!

I received the chips from National, however they are very very small. I have a fine tipped soldering iron but I don't think it's going to cut it. Do I have to design a schematic and then have it printed so I can just lay all the pieces on it or what? Any tips? :(

I received the chips from National, however they are very very small. I have a fine tipped soldering iron but I don't think it's going to cut it. Do I have to design a schematic and then have it printed so I can just lay all the pieces on it or what? Any tips?

"surf board..." as an EE student, a product that you'll learn to love, trust me.

As for soldering, pre-tin the surfboard pads, hold the chips down in the correct orientation and location using the "tripod trick" and heat the legs to attach to the tinned pads.

"tripod trick" = a pin clamped perpindicularly into the jaws of a needle nose pliers, tightly fastened with a rubber band... use the pin point to hold the chip down and the handles of the pliers to form the other two "legs of the tripod."

A few comments...

Check the AN-1493 for the LMH1251 ... it says you also need a dual d-flop if you want to handle 1080p. Semiconductor vendors don't like to disclose undesirable operation and tend to minimize the need for fixes - be prepared to find that the fix-up is needed for more than 1080p.

In the same vein... check for undesirable interaction with macrovision early on. There's no reason that there should be, but content protection support might not be disclosed on the publicly available data sheets.

It saves a lot of time spent rebulding circuits that otherwise fall victim to their creator if you don't assume anything about the incoming power from a power brick or a bench supply. Add a diode to prevent reverse polarity hookup and add your own fixed linear regulator(s).

The DigiKey catalog has some proto boards for some SMT parts, and there are DIP pin converters for others. Failing that if you have a schematic capture and PWB layout tool set you would use that, otherwise you would have to use one of the little layout packages that the quick-turn proto board people let you use.

It is possible to wire these "dead bug" style, on their backs with their legs in the air. You can glue them to a blank board, or a through hole proto board you use for other parts, like a linear regulator and bulk bypass. You wire with wire-wrap wire or self-stripping (heat stripped) magnet wire in the #32 to #36 range, thin solder, a magnifier light or a 3x stereo microscope. Expect to spend around 2 minutes per component terminal once you get the hang of it. You only do this if you're only making one and the PWB layout process was too much to get started on.

mport006: Isn't the VGA001 product from Mayflash just a LMH1251 chip? The descriptions are just the same... I e-mailed them asking if this is true, but they wouldn't tell me :mad: .
Search for mayflash on google.

Hi guys,

I have been searching the net for a vga converter so I can plug in equipment (via scart, video out, rgb) such as my satellite receiver, Xbox, dvd player to my PC tft monitor at as high a resolution as possible (eg 1024 * 768). So far I have found units costing over £70 ($130+).

Being an electronics enthusiast I thought I could make such a device for much less and just as good subject to finding some plans and component list.

Can someone confirm whether the device you are discussing/making here can do what I am after?

I would love to be able to watch satellite on a large Dell ultrasharp monitor!!!


Thanks in advance.

Mark.