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-   -   10-bit color and VDPAU (http://www.nvnews.net/vbulletin/showthread.php?t=164684)

johnc 07-24-11 10:47 PM

10-bit color and VDPAU
 
Hi... just looking for some info to educate myself here.

I have a Fermi card that does hardware acceleration of 1080p H.264 through VDPAU and DXVA.

The morons in anime circles are talking about moving H.264 encoding to Hi10p (i.e., using 10-bit color). They don't see any issue here because codecs and video players support 10-bit color decoding and playback these days.

But my understanding is that you can't use hardware acceleration of 10-bit color encoded H.264 streams... which makes the whole concept stupid.

So, for my edification, is hardware accelerated decoding of 10-bit streams not possible due to a lack of support in:

- the actual hardware components (say GeForce or ION chips);
- video card firmware;
- video drivers; or
- VDPAU / DXVA libraries?

I'm not necessarily referring to 10-bit output -- just the onboard decoding of the stream.

Thanks,
John

jlippo 07-25-11 07:02 AM

Re: 10-bit color and VDPAU
 
Decoding is most likely done using Cuda, which means there is no dedicated hardware for video acceleration.
If this is the case the problem is in libraries/driver whichever handles the actual decoding.

Gusar 07-25-11 07:05 AM

Re: 10-bit color and VDPAU
 
It's not about 10bit colors. But about 10bit internal encoder/decoder precision. And they're not at all morons for going this route, 10bit help a lot with gradients and preventing banding, so anime is pretty much the biggest benefactor of it.

That said, it would be nice if VDPAU could play 10bit videos. Are you sure it can't?


@jlippo: Decoding is done on dedicated chips, not with cuda. The only thing that happens with shaders is post-processing, meaning the presentation part of VDPAU.

johnc 07-25-11 08:04 AM

Re: 10-bit color and VDPAU
 
Quote:

Originally Posted by Gusar (Post 2459568)
It's not about 10bit colors. But about 10bit internal encoder/decoder precision. And they're not at all morons for going this route, 10bit help a lot with gradients and preventing banding, so anime is pretty much the biggest benefactor of it.

That said, it would be nice if VDPAU could play 10bit videos. Are you sure it can't?

Of course 10-bit is a great idea -- if it didn't come with this cost. Though the actual visible benefits appear to be minimal, from the videos and screencaps I've seen.

I'll try playing a Hi10p video using VDPAU later today and report back. But my understanding is that this is a deficiency at the hardware level, so we're probably not talking about a driver or VDPAU update. But this is what I would really like to confirm: hardware vs. software.

And the reason it's moronic is that -- if true -- it forces people off of hardware acceleration, which to me appears to be a major regression. I guess there is just an overall detachment from the rest of the universe that I find extremely offputting about the fansubber community. It's not just this particular case -- this is a common theme. You have to play using the one, correct, established means of video playback, to the exclusion of everything else. On the surface that seems kind of silly, but when you dig deeper to see what the actual established method of video playback is -- a cluster-f of hacked-up programs and decoders -- it makes it all the worse.

artem 07-25-11 09:00 AM

Re: 10-bit color and VDPAU
 
Where did they find the 10bit source material?

johnc 07-25-11 09:54 AM

Re: 10-bit color and VDPAU
 
I don't think the source material is 10-bit. They're just encoding it 10-bit to get better compression and video quality.

johnc 07-25-11 10:18 AM

Re: 10-bit color and VDPAU
 
I tried feeding one of these Hi10p files into mplayer2 w/ vdpau enabled and it just crashed. I had to resort to the xv driver to get playback.

Gusar 07-25-11 10:25 AM

Re: 10-bit color and VDPAU
 
Quote:

Originally Posted by artem (Post 2459590)
Where did they find the 10bit source material?

You don't need 10bit source for this to be useful. The output will be 8bit anyway. It's about what the encoder does internally.
The plan for later is to also automatically add a dithering filter into the encoding chain. Doing this increases image quality, but with 8bit precision it comes with a significant increase in required bitrate. But with 10bit precision you get the better picture without requiring a higher bitrate.

@johnc: Do report back, but somehow I have a feeling that it won't work, that it'll require new hardware. Which in a way is a shame, but anime fansubs aren't HD anyway, are they? So any remotely modern processor shouldn't have a problem with it. And it seems they're doing it for a smaller filesize. So instead of increasing quality, they're going for same quality at lower bitrate.

johnc 07-25-11 10:42 AM

Re: 10-bit color and VDPAU
 
Quote:

Originally Posted by Gusar (Post 2459640)
@johnc: Do report back, but somehow I have a feeling that it won't work, that it'll require new hardware. Which in a way is a shame, but anime fansubs aren't HD anyway, are they? So any remotely modern processor shouldn't have a problem with it. And it seems they're doing it for a smaller filesize. So instead of increasing quality, they're going for same quality at lower bitrate.

I think with a modern desktop processor one would be okay. My old AMD Opteron (dual core 2.2 GHz) can handle just about all 1080p anime content -- but just barely in some spots -- except for maybe rare circumstances such as highly-refined scrolling subtitles. I don't know if it can handle Hi10p 1080p yet as I don't have any 1080p samples to try. Not that it matters much for me since I have another system that is more than capable.

But my concern is on low-end, modern hardware such as purpose-built HTPCs. E.g., the Zotac ION that has a low-clocked CPU to keep temps down, and shoves the video decoding work off to the GPU. Take the GPU out of the mix and it seems like it'll be a bit tight, if not impossible.

If it's a hardware thing, then that's a real ball-buster... because if it became a trend it would pretty much obsolete everyone's GPU -- from the aspect of video decoding at least.

olifre 12-27-11 11:25 PM

Re: 10-bit color and VDPAU
 
Sorry to awaken this old thread.
I saw the new beta release (295.09) supports 30 bit depth display devices. The README also states, if I switch to 30 bit depth, and my display is connected via LVDS (Laptop), dithering will happen automatically.

I did not yet try to switch my Xserver to 30 bit (will do so tomorrow), but does this mean something is happening / has happened on the VDPAU-front too? If there is now support for 30 bit displays, Hi10P-decoding might be the next step. At least, the rendering part should work already with the VDPAU-overlay, I guess?

Gusar 12-28-11 09:30 AM

Re: 10-bit color and VDPAU
 
It's two completely different things, that 30 bit output support has nothing whatsoever to do with video decoding.

Plagman 12-28-11 06:02 PM

Re: 10-bit color and VDPAU
 
And it's been supported for a very long time, support isn't new with the 295 series. I'd have to check whether our video decoding blocks support 10bpc video, but I'd be surprised. In any case mplayer shouldn't crash when opening these files, that might either be an mplayer/ffmpeg or VDPAU bug. Can anyone attach a clip that reproduces the issue or upload it to the partner SFTP as per the sticky instructions?


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