[NerdWithNoLife]

I have a TV. I think it's a great TV - which is why I don't want to watch HD on my computer! My couch is in the living room, not the computer room for a reason. I would, however, like to record OTA HD on my computer, then send it back to the TV. But I have a cheap weird idea on how to to it - perhaps an impossible way.


See, my TV has a built in tuner. If only there was a way to record an ATSC signal and return it to the TV in the same way - ATSC via RG6 coax. I would want it to be the exact same signal, just played back later. This way, my computer would not have to do a bunch of heavy live thinking and that would allow for a dumber (and cheaper computer).


Is there any way to do that? I just want the same signal only at a later time. I know that if I skipped forward and back there would be pixellization but I don't care. As long as the TV can pick up the stream from a given moment in the timeline, that's fine with me. Also if this is possible, it would eliminate the need for and HDMI out card. I would just need to send out the identical ATSC signal. Same in, same out. Maybe I'd need an A/B switch to change from real OTA to prerecorded OTA, but I'd be okay with that too.


Does anyone have a solution for this problem?

 

[WS65711]

You need an ATSC RF Modulator like this:

http://www.computermodules.com/broad...odulator.shtml

 

[NerdWithNoLife]

I think that modulator is designed to take HD sources like pc/bluray/hddvd and convert them to an ATSC feed ($$$). I don't need the extra expense. What I'm looking for is a way to simply take the transport stream and play it back through coax exactly as it was received. I suppose that would require some sort of card with ATSC out.


This way the computer would not have to do live decoding. Wouldn't that allow for a simpler low end computer (with a large hard drive, of course)? ATSC in, then ATSC out. No translating.

 

[WS65711]

You said you wanted an ATSC signal into your TV tuner via RG6 coax.

The only way to do that (AFAIK) is to modulate the signal and then

let the TV tuner decode it.

 

[timecop]



Quote:
I think that modulator is designed to take HD sources like pc/bluray/hddvd and convert them to an ATSC feed ($$$). I don't need the extra expense. What I'm looking for is a way to simply take the transport stream and play it back through coax exactly as it was received. I suppose that would require some sort of card with ATSC out.

Yeah, thats exactly what a modulator does.

The ones that store digitized RF to storage arrays and then play back cost even more than a static RF generator-only. You're not going to get a "cheap PCI card" to do it with.

Comparable products from DeKtec/Alitronika/etc start at $2000 and go up.

 

[ctdish]

Probably the most affordable way to move the HD signal from one room to another is to use ethernet to a media player like the ROKU or something more modern.

John

 

[HoustonPerson]

Yeah I want an ATSC RF out of my Sony DHF-HDD500, It gave me a headache so I gave up. Honestly, I think it should only cost $10 !! If they built in in the box it would only be $1.00

 

[NerdWithNoLife]

I've decided to buy the MyHD MDP-130 card.


The reason I brought this up is because I want to use my computer as a DVR but NOT AS A TELEVISION. I was trying to avoid the need for ALL of the following 1) a high end computer 2) a high end video card 3) an HD tuner card.


Recording HD doesn't take nearly as much processing as decoding and playing it. Fortunately this MyHD card decodes in its hardware which allows for a cheaper computer AND IT OUTPUTS TO THE TV! WOW! This could truly be the poor man's HDDVR.


I'll let you know how it works out. My fingers are crossed on drivers/system conflicts. But there is a great section of forum dedicated to the card so I think I'll manage. While this doesn't technically solve the RF out idea I had, it is a perfect solution for what I want. I hope the timeshifting works on my PC, but even if I just have the capability to record/playback HD I will be a very happy guy.

 

[stephenju]

I thought MyHD output via DVI, not RG6?

 

[Ken H]

There is no consumer RF modulator for ATSC. The pro units are very expensive.

 

[sneals2000]



Quote:
Originally Posted by Ken H /forum/post/0


There is no consumer RF modulator for ATSC. The pro units are very expensive.

Didn't one of the early HD satellite receivers have an ATSC modulator side-car? ISTR that it was made obsolete by a transmission system change. Wonder if something like that could be coaxed into performing a similar task - AIUI it took the satellite MPEG2 transport stream, tweaked it into an ATSC broadcast friendly version and then modulated it to an RF channel?


Think it was the Dish network thing detailed here :

http://www.coolstf.com/mpeg/HDTV/index.html


Suspect it isn't feasible to hack this to work (it is designed to accept a DVB-S transport stream) - but it is a theoretical possibility I guess (wonder if you could take the ATSC Transport Stream you've recorded, transcode it to a DVB-S stream, feed this into the Dish box for it to convert it back?)...

 

[CKNA]



Quote:
Originally Posted by sneals2000 /forum/post/0


Didn't one of the early HD satellite receivers have an ATSC modulator side-car? ISTR that it was made obsolete by a transmission system change. Wonder if something like that could be coaxed into performing a similar task - AIUI it took the satellite MPEG2 transport stream, tweaked it into an ATSC broadcast friendly version and then modulated it to an RF channel?


Think it was the Dish network thing detailed here :

http://www.coolstf.com/mpeg/HDTV/index.html


Suspect it isn't feasible to hack this to work (it is designed to accept a DVB-S transport stream) - but it is a theoretical possibility I guess (wonder if you could take the ATSC Transport Stream you've recorded, transcode it to a DVB-S stream, feed this into the Dish box for it to convert it back?)...

That modulator was fed Mpeg2 transport stream derived form DVB-S. Mpeg2 TS in ATSC and DVB is very similar as far as audio and video goes.


It can't be hacked because it has to work with E* satellite receiver. It does not work by itself.

 

[timecop]

Obviously, that would be the hacking part.

 

[sneals2000]



Quote:
Originally Posted by CKNA /forum/post/0


That modulator was fed Mpeg2 transport stream derived form DVB-S. Mpeg2 TS in ATSC and DVB is very similar as far as audio and video goes.


It can't be hacked because it has to work with E* satellite receiver. It does not work by itself.

Yep - my point was that it would need to be hacked to work - though whether this is feasible is the question. I suspect it isn't. However it does demonstrate that an ATSC modulation solution is achievable at a consumer price point - though it would be a reasonably niche device so may not achieve scaling cost reduction.

 

[ChrisW6ATV]

The Dish modulator included a Zenith ATSC modulator chip that they made in the earlier days of HDTV, but this may be the only product that ever used that chip, which was intended for consumer-level equipment if I remember right.


The Dish modulator would output any Dish Network channel that included Dolby Digital audio, even SD channels, so it may still be possible to hack one to make it work. This could be a monumental project, though, and I have too many other hobbies and interests to take it on. Such a scheme would need, at the least, a large MPEG-2 file with DD audio (or a series of files along with a "playlist"/chaining ability), a program to format the MPEG file(s) into "transport stream" format, probably on-the-fly, and a hardware interface to get the TS data into the right connections in the Dish modulator as well as power it. This project would probably have to start with the modulator attached to a Dish 5000 receiver in order to begin figuring out its connector pin functions. A subscribed 5000 (if Dish even allows them) tuned to an SD channel with DD audio might even still make the modulator work, and could possibly be used to get a lot of information on how it does its job.


Much more feasible, though, probably, is getting a Sencore HDTV995 or HDTV996, and preloading it with TS files.

 

[Rick_R]

I am sure the real reason that there are no ATSC modulators is that doing so puts HD programming in the unencripted and copyable domain. I mean, as the previous posters have mentioned, it is just a chip and that chip already exists reasonably cheaply. However to output HD programming in the ATSC domain allows unlimited copying. That is why it is not done.


Rick R

 

[CKNA]



Quote:
Originally Posted by Rick_R /forum/post/0


I am sure the real reason that there are no ATSC modulators is that doing so puts HD programming in the unencripted and copyable domain. I mean, as the previous posters have mentioned, it is just a chip and that chip already exists reasonably cheaply. However to output HD programming in the ATSC domain allows unlimited copying. That is why it is not done.


Rick R

Absolutely not. It has nothing to do with copying as all OTA is unecrypted. The main reason is cost. Parts are expansive. Dish modulator was $300 by itself. Anyway any ATSC modulator would be used with people own stuff. Dish product was unique as it allowed them to send HD without really having HD receiver. Besides I can record form cable as much as I want, and OTA channels are pased uncrypted.s

 

[sneals2000]



Quote:
Originally Posted by Rick_R /forum/post/0


I am sure the real reason that there are no ATSC modulators is that doing so puts HD programming in the unencripted and copyable domain. I mean, as the previous posters have mentioned, it is just a chip and that chip already exists reasonably cheaply. However to output HD programming in the ATSC domain allows unlimited copying. That is why it is not done.


Rick R

Not sure that is entirely the case - as cable boxes with Firewire outputs allow a degree of recording of many channels don't they?


I think the issue is that ATSC modulators are not widespread, and are thus not "commodity level" cheap - so are likely to be tens of dollars not cents at least.


I suspect when the original Dish model was launched it was cheaper to provide an ATSC modulator than an HD MPEG2 demodulator (which was duplicated in an ATSC TV with 8VSB demodulator and decoder) - and effectively removed pretty much any "HD" requirements from the receiver - it just had to pass on a transport stream for slight processing and remodulation. (It is kind of similar to the Mitsubishi D-VHS machines that only deal with HD in terms of a Firewire-carried transport stream - they have no HD video processing in them whatsoever)


Once HD MPEG2 decoders became viable, and as the market developed and delivered a lot of NTSC tuner equipped HD capable displays (i.e. displays without ATSC tuners) it became more viable to build satellite receivers with component (and now HDMI) outputs instead.


It is one of those - technically possible, but commercially unlikely to happen, kind of things. Quite annoying if you have a requirement for it though.


{Incidentally - at least one hacker has produced code that generates a VHF DVB-T signal from a VGA video card by creating a VGA video signal that creates harmonics that will be tuned by many DVB-T receivers. Creating the VGA signal in real time isn't feasible sadly - but it is a great hack}

 

[ChrisW6ATV]

The biggest reason that ATSC home modulators will probably never be commonly available is that there will not be a big market for them. Analog RF modulators were widespread simply because TV sets did not have direct A/V inputs in the early days of VCRs and video disc players. For people who truly do need/want to distribute HD signals to other rooms, the current most cost-effective way is probably to use "Cat 5 baluns", devices that convert component or RGBHV signals to allow them to be carried on Cat 5 hard-wired network cables. These cables are inexpensive and can be relatively easily installed from one room to another.

 

[Rick_R]

My Dish Network 622 HD DVR allows for a second TV to be controlled by the DVR. The output for that second TV is an analog signal on channel 14-60. This makes the requirement that the second TV is not a HDTV. If they put an ATSC signal out instead then this second TV could be a HDTV making the 622 even more valuable. I am sure that one of the reasons that the second TV output is analog is because that is cheaper. However since Dish will not put firewire on their STB an additional reason they do not put out the second TV as ATSC is because my OTA firewire STB/DVHS combo could then record the show.


Rick R