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SDI vs HDMI 480i  

post #1 of 175
Thread Starter 
I am sure some you have experimented with both SDI & 480i over HDMI feeding your standalone VPs.

Does an SDI mod'd DVD player still offer some real picture quality advantage ?

..... just trying to figure out what route to take next !

- Andy
post #2 of 175
Andy SDI is much better than HDMI, here are the reasons:

-technically more pure, doesn't have HDCP or audio added in the chain
-SDI is directly and I mean directly from the mpeg chip
-using SDI allows analog output from scalers etc.(a must for CRT projector users)
-SDI signals can be sent much further than HDMI and are more robust
-BNC connection is more stable and secure than HDMI
-no HDMI 480i players can come close to the SDI mods on the best mpeg decoders ever, the Panasonics from a few years back

nothing beats a SDI modified Panny RP91/RP82 and their clones

-Gary
post #3 of 175
Quote:


-technically more pure, doesn't have HDCP or audio added in the chain

SDI can have 4 embedded audio channels, as well as abundant ancillary data.

Quote:


SDI is directly and I mean directly from the mpeg chip

Only if the MPEG decoder has an SDI output...which they don't. Otherwise, the data has to be serialised, just like HDMI.

There is no image quality difference between SDI and HDMI.
post #4 of 175
Quote:
Originally Posted by Targus View Post


There is no image quality difference between SDI and HDMI.

not true, the fact that HDCP has been added to HDMI would give SDI the upper hand in a purity stand point

also the fact the no players with mpeg decoders as good as the Panasonics have HDMI output, so SDI is better than HDMI in every way because of the quality of mpeg decoders in the units we are comparing

-Gary
post #5 of 175
Quote:


not true,

...the stuff you've posted as fact, is, in fact, not true.

Your lack of technical knowledge is frightening, please look this stuff up before posting.
post #6 of 175
HDCP should not change the video data in any way once properly decoded. Yes, it is extra baggage to carry alomg but it's not going to affect image quality. Now 480i HDMI technically should not contain HDCP because it's under the maximum unprotected resolution limit. However I do agree many manufactures will not think this out and will just apply HDCP to anothing leaving the HDMI port.

As stated SDI can (and does in many professional installations) carry 4 full bandwidth (48khz) AES channels. HDSDI can actually carry 16!

What leaves the MPEG decoder chip in "modifiable" players is either a Bt656 or Bt601 8 bit parallel stream with a clock line. A Bt656 stream can simply be serialized with a single chip. A Bt601 stream must pass through some logic to add the EAV/SAV words which imply H&V sync. Generally an FPGA but I remember the days in the early 1990s when this was a PC board area the size of a business evenlope to do this with TTL chips and some crude programmable logic!

SDI is a true unbalanced serial interface needing only a sigle wire and a return wire - coax. Twisted pair is entirely possible but no standard exists for it's use. I have seen a demonstration by Belden carrying SDI over a single CAT5 pair.

HDMI is not fully serial inthe same sense. While the individule data channels, Y,pB,pR rae serial streams, there are three of them along with a clock. These four signals are balanced LVDS signals. So HDMI is also a PARALLEL interface in a sense. The problem is data skew. On a long cable it's not possible to make the fuor pairs exactly the same physical legnth. At some point this delay causes data skew. At worst case a data pair may actualyy be delayed into the next clock pulse resulting in visual chaos.

SDI is far more robust than HDMI. It can travel much greater distances over inexpensive cable.
post #7 of 175
Targus,

IMHO, Andy and Gary are talking about commercial DVD's, Movies and Television programs.
Quote:
Originally Posted by Targus View Post

SDI can have 4 embedded audio channels, as well as abundant ancillary data.....

If this is true, common sense and logic would dictate that "4 embedded audio channels" and/or "abundant ancillary data" would not be put on media entertainment DVD's, as any extra information that would take up needed space would affect the overall PQ. If this extra information is not on the disc, then the SDI signal would be superior to the HDMI counterpart.

Paul
post #8 of 175
Quote:
Originally Posted by Paul H View Post

Targus,

IMHO, Andy and Gary are talking about commercial DVD's, Movies and Television programs.

If this is true, common sense and logic would dictate that "4 embedded audio channels" and/or "abundant ancillary data" would not be put on media entertainment DVD's, as any extra information that would take up needed space would affect the overall PQ. If this extra information is not on the disc, then the SDI signal would be superior to the HDMI counterpart.

Paul

The SDI standard (SMPTE 259) does have the ability to carry four audio channels as well as some other ancillery data. However that is not encoded in the DVD image that way. The DVD audio is where the DVD format specifies it. SDI is merely a transmission specification. In fact a DVD contains at least 6 channels of audio considering 5.1, plus more with alternate laguanges. Some DVD encoders are fed audio via SDI but it's stripped and encoded seperatly. In most authroing scenerios, audio is handled from a seperate pass from a dedicated digital audio tape, typically a Teac DA98 format. Reason - no SD digital VTR has more than 4 audio channels. That;s two short for full 5.1. (HD VTRs have 8 or 12 channels).

The addition of audio data in the video stream in either SDI or HDMI has no ill effects on video quality or bandwidth. The space is allocated for it. If you don't use it, then that space is empty. But the space reserved for video data transmission remains the same.

Adding audio to SDI or HDMI does not compromise the video data payload in any way. Now the more audio channles on the disk, the less room for video, but that's a different issue altogether.
post #9 of 175


So when it is said that a DTS track wasn't put on a DVD because it would take up too much valuable space, compressing the video portion further - would not be an accurate statement?
post #10 of 175
Thread Starter 
Thanks for the tech info.

But what will my eyes see using an SDI player mated with the likes of a Lumagen/DVDO/Crystallio2, as compared to a 480I HDMI player ?

I happen to have a Panasonic XP50 with SDi from my Immersive Holo3D-2-Aux days, and am not sure if I should keep it for future use, or sell it off. But Methinks I should keep it in my closet of treasures, considering it might only fetch < $300 at the buy & sell sites.

- Andy
post #11 of 175
Quote:
Originally Posted by Gary Murrell View Post

nothing beats a SDI modified Panny RP91/RP82 and their clones

I wouldn't trade my 963SA for one.
post #12 of 175
Quote:
Originally Posted by Targus View Post

...the stuff you've posted as fact, is, in fact, not true.

Your lack of technical knowledge is frightening, please look this stuff up before posting.

I never said they were facts did I ? your blind comments(like about Monster) are what is frightening

who cares if SDI can carry audio?, that doesn't apply to our situation in anyway shape or form, there have been face offs comparing HDMI to SDI on the same player, take a guess which one won?

SDI can travel longer, doesn't have HDCP which leads to analog output problems, uses a much better BNC connector in 99% of cases and is actually better in picture quality, sorry it has been proven

Andy you have the best there is, the XP50 is at the top of the heap, no need for anything else, the XP50 also doesn't have a spindle motor defect either, Do Not get rid of it

Carl I have yet to have a Philips on my bench, I tend to avoid the 601 players with the 2 extra channels as the SDI products are much more expensive

-Gary
post #13 of 175
Quote:
Originally Posted by Gary Murrell View Post

I tend to avoid the 601 players with the 2 extra channels as the SDI products are much more expensive

Understandable, although "much" is probably overstating the case slightly.
post #14 of 175
Quote:
Originally Posted by Paul H View Post



So when it is said that a DTS track wasn't put on a DVD because it would take up too much valuable space, compressing the video portion further - would not be an accurate statement?

It is entirely accurate. The disk only has so many gig's of capacity. But we are talking about the interface here, not the disk capacity. Both interface standards have reserved capacity for digital audio. Adding it or not does not change the allotted video banswidth.
post #15 of 175
Quote:
Originally Posted by Targus View Post

There is no image quality difference between SDI and HDMI.

That's very blanket statement and not really true.

Yes, an optimal HDMI implementation *can* theoretically be identical to SDI. However, in most cases SDI still looks better in real life. Why? Because most DVD players do harm to the video stream before outputting it over HDMI.

E.g. I've been told by UK custom installers that an SDI modded Arcam DVD player still looks ever so slightly sharper than the HDMI output of the very same player. The difference is very small with Arcam, though, and only visible on very large displays. However, Arcam are known for a very good HDMI output. Most other DVD players do worse than that. E.g. most HDMI players don't even support 480i output. And YCbCr output is also not available in every HDMI DVD player.
post #16 of 175
Quote:
Originally Posted by madshi View Post

That's very blanket statement and not really true.

Yes, an optimal HDMI implementation *can* theoretically be identical to SDI. However, in most cases SDI still looks better in real life. Why? Because most DVD players do harm to the video stream before outputting it over HDMI.

E.g. I've been told by UK custom installers that an SDI modded Arcam DVD player still looks ever so slightly sharper than the HDMI output of the very same player. The difference is very small with Arcam, though, and only visible on very large displays. However, Arcam are known for a very good HDMI output. Most other DVD players do worse than that. E.g. most HDMI players don't even support 480i output. And YCbCr output is also not available in every HDMI DVD player.

I think the way it was presented was to harsh coming from a real fan of sdi . With you most of us would have the view that sdi and hdmi can be the same in PQ but it seems most are not when doing real testing. We all asume this is because 'stuff is done to the signal' before it reaches the output. Now the question is have we looked at examples of what is done ? I myself use SDI since it seems to be a sure bet compared to using hdmi out at this stage but i would love to know what kinda of 'things' are done to the signal to create this difference in real world tests.

Or could it be that somehow the chips in the chain itself (when using hdmi) that give the difference in results i mean they sofar all use the same chips from SI no?

Also i would like to add one more (small) reason to use SDI for dvd, if your scaler has a SDI in it means you will keep 1 extra hdmi free. Like alot of things with scalers small things add up for me its the points Gary pointed out plus this.


Daniel.
post #17 of 175
Quote:
Originally Posted by danielo View Post

Now the question is have we looked at examples of what is done ? I myself use SDI since it seems to be a sure bet compared to using hdmi out at this stage but i would love to know what kinda of 'things' are done to the signal to create this difference in real world tests.

Good question and I would like to know that, too. Possible things a DVD player could do to the video stream are:

(1) Color space conversion.
(2) Clipping of BTB/WTW.
(3) Deinterlacing.
(4) Noise reduction.
(5) Filtering (e.g. CUE filtering or vertical filtering).
(6) Color "correction".
(7) Overscan.

Some of these are not necessarily bad in itself - but bad if you use an external video processor which most probably can do all these things better.

But as you said, maybe there are more things than that going on behind the scenes, which we don't know of.
post #18 of 175
DVD players sometimes scale the image, too. I know mine scales VCDs for no obvious reason.
post #19 of 175
Quote:
Originally Posted by madshi View Post

(4) Noise reduction.

Some of these are not necessarily bad in itself - but bad if you use an external video processor which most probably can do all these things better.

well let's just say for argument sake, for this the additional processing could actually be gd, if the HDMI is done properly and the external video processor is deficient in NR. A prime example will be the upcoming Denon 3930, if the 480i output (it supports) can have HQV NR applied first (this part is unknown yet), then a VP30+ABT102 will benefit greatly from this output.

In all honesty I think both depend on how well it is done. A SDI mod can probably also be done poorly that introduces unwanted "jitters" (is there such thing in video?) Since all these mods are after-market, at least for the connector part the builtin "path" can be better. So ideally they all should have no difference, just that in reality the HDMI implementation so far is pretty poor.
post #20 of 175
Danielo and Madshi have pretty much said it all, I rest my case

-Gary
post #21 of 175
Quote:
Originally Posted by c722 View Post

well let's just say for argument sake, for this the additional processing could actually be gd, if the HDMI is done properly and the external video processor is deficient in NR. A prime example will be the upcoming Denon 3930, if the 480i output (it supports) can have HQV NR applied first (this part is unknown yet), then a VP30+ABT102 will benefit greatly from this output.

You could, theoretically, put the SDI in after the realta in such a case, assuming that it puts out normal bt.601/656 in YCbCr 4:2:2 16-235. Even if it doesn't, you could go really whacked out and connect a i2c terminal up to it, and reprogramme it to do so.

Quote:


In all honesty I think both depend on how well it is done. A SDI mod can probably also be done poorly that introduces unwanted "jitters" (is there such thing in video?)

HDMI has no less jitter than SDI does.

Quote:


Since all these mods are after-market, at least for the connector part the builtin "path" can be better.

I've never seen a case where that has happened in practice.
post #22 of 175
Quote:


That's very blanket statement and not really true.

This is a perfect example:


Quote:


Yes, an optimal HDMI implementation *can* theoretically be identical to SDI. However, in most cases SDI still looks better in real life. Why? Because most DVD players do harm to the video stream before outputting it over HDMI.

A "blanket" statement, with very little basis in reality....like most of the other posts by the SDI experts in this thread.
post #23 of 175
Quote:
Originally Posted by Targus View Post

A "blanket" statement, with very little basis in reality....like most of the other posts by the SDI experts in this thread.

Quite the contrary. What I posted is confirmed in numerous threads by almost all people who have real life experience with SDI vs. HDMI.
post #24 of 175
Quote:
Originally Posted by Glimmie View Post

Now 480i HDMI technically should not contain HDCP because it's under the maximum unprotected resolution limit. However I do agree many manufactures will not think this out and will just apply HDCP to anothing leaving the HDMI port.

I am under the impression that the CSS spec/license forces manufacturers of DVD players to apply HDCP to all resolutions, including 480i.
post #25 of 175
I think I'm following all thisI think. Pretty much over my head, as with 90% of the posts on this board. But I keep reading and trying to learn anyway. Advil helps........

Where would the Oppo 970HD fall into this discussion? Didn't they target VP owners with this machine? Have they done something different with the data stream that would make the machine comparable to a SDI modified player?
post #26 of 175
Quote:
Originally Posted by madshi View Post

Quite the contrary. What I posted is confirmed in numerous threads by almost all people who have real life experience with SDI vs. HDMI.

I have a Pioneer AVi59 modded by Patrick of Lumagen for SDI output. It's mated to the Lumagen HDPro. I have run numerous tests, both using DVE and films, to see if there is a difference between HDMI and SDI.

Guess what - there is a measurable difference. The HDMI has noticable ringing on the DVE resolution test pattrern - there is none via SDI. Also, and I admit this may be subjective, viewing a movie via SDI seems more fluid with marginally better blacks and colors.

Frankly, I don't care why there is a difference, but I'd tell anyone to consider an SDI mod if they use a video processor that accepts SDI input.

PS: folks here don't take likely to 'blanket statements' - much better to share your personal experience. YMMV.
post #27 of 175
@J.Mike - thanks!
post #28 of 175
Quote:
Originally Posted by Carled View Post

You could, theoretically, put the SDI in after the realta in such a case, assuming that it puts out normal bt.601/656 in YCbCr 4:2:2 16-235. Even if it doesn't, you could go really whacked out and connect a i2c terminal up to it, and reprogramme it to do so.

but isn't doing this a bit out of the way ? guys I'm not disagreeing SDI is superior at the moment. My point is, ideally both should be the same. Just at the moment no HDMI transport is done properly yet. It doesn't mean this cannot be done. Unless someone can tell me it's technically impossible to achieve the same in HDMI. (I'm having high hopes on the Denons)

Quote:


I've never seen a case where that has happened in practice

I'm referring strictly to the mod. I've not done a SDI mod myself, but I have done audio mod before (simple changing of capacitors/clock chip). The skill makes some difference. The connections done at an aftermarket mod, IMHO, usually does not match the clean connection in an integrated PCB. Especially when you tap a chip via its pin out. The current drain and DC grounding itself is already an issue (well at least for audio we have to try to see). SDI in commercial environment is different.
post #29 of 175
Quote:
Originally Posted by J.Mike Ferrara View Post

I have a Pioneer AVi59 modded by Patrick of Lumagen for SDI output. It's mated to the Lumagen HDPro. I have run numerous tests, both using DVE and films, to see if there is a difference between HDMI and SDI.

Guess what - there is a measurable difference. The HDMI has noticable ringing on the DVE resolution test pattrern - there is none via SDI. Also, and I admit this may be subjective, viewing a movie via SDI seems more fluid with marginally better blacks and colors.

J. Mike, I have a DV-59Avi also and have been thinking about SDI modding it. One thing that bugs me is that the "direct" mode on the 59 will not pass BTB. A person has to enable additional processing to get it to pass BTB which may be one reason why SDI is better than HDMI on that particular player. But before I speculate, can you tell me if in fact you get BTB/WTW via SDI?
post #30 of 175
I was thinking the same thing Mark. If you use the "DIRECT" mode out of the 59AVi then it "should', you would think, be pretty much the same as SDI Although I have found the same thing you mention to be true with mine also.

My take on it is if you feel that the small amount of image quality is worth the added expense of going SDI, then just do it.

There are so many variables that can creep into each one that I think personal experimentation is definitely in order to see which combo works best and/or makes it worth the money.
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