XvMC support

[chrisr]

Yes, but that should be at the bottom of the priority list because we can live without it :P MPEG2 takes ~5% of your CPU lol.

That's still ~5% I could use for something else.

This just needs good overlay support, not XvMC. I thought overlay is supported for those old cards?

Huh? Of course R100/rv100 has overlay support. But the older CPU in this machine would definitely benefit from having any amount of work offloaded! Obviously.

[RealNC]

That's still ~5% I could use for something else.

But it's still 5% and therefore not as important as other issues

Huh? Of course R100/rv100 has overlay support. But the older CPU in this machine would definitely benefit from having any amount of work offloaded! Obviously.

Still it's an old machine and there are other issues more important

Don't take me wrong on this though. Of course it would be nice to have MPEG2 acceleration. It's just that, in my opinion, driver development should be focused on getting the more important bits implemented right now since XvMC is not going to help with MPEG4 which *would* be a high priority *if* XvMC would be suitable for it.

[TechMage89]

I think an implementation of VDPAU OR VA-API in the open-source drivers would be the way to go. It would primarily be useful for media PCs, but it definitely would be cool (and if it actually worked right, it would be better than Windows' video decode accel.)

That said, I think fully featured, fast 3D and 2D acceleration take precedence, because the use case for accelerated video decode is still smaller (most procs can handle even hi-def h264, and most people don't multitask while watching video).

[RealNC]

I just found this in Wikipedia's XvMC article:

XvMC also supports offloading decoding of mo comp, iDCT, and VLD ("Variable-Length Decoding", more commonly known as "slice level acceleration") for not only MPEG-2 but also MPEG-4 ASP and MPEG-4 AVC (H.264) video on VIA Unichrome (S3 Graphics Chrome Series) hardware.

Is this true? If yes, how? Can we have it too? Please? :P

[curaga]

My Pentium2 333Mhz can handle xvid at dvd resolutions. With the help of a Rage Pro and full vidix accel, but still.

@RealNC: Yes, it's true. You'll need however the Via binary drivers, and to patch & compile mplayer. Don't remember right now if Via had a patch for Xine too.

[deneb]

XvMC also supports offloading decoding of mo comp, iDCT, and VLD ("Variable-Length Decoding", more commonly known as "slice level acceleration") for not only MPEG-2 but also MPEG-4 ASP and MPEG-4 AVC (H.264) video on VIA Unichrome (S3 Graphics Chrome Series) hardware.

I don't think they actually had support for H.264 acceleration, neither in software nor hardware, only H.263 and maybe MPEG-4 ASP in addition to MPEG-2. Haven't used the driver myself though.

[agd5f]

Are we just talking about just R500+ here? I do have older machines with CPUs barely capable of MPEG2: R100, for example. (Or possibly rv100 - it's a Radeon 7000.)

If someone was inclined, MC acceleration could be implemented with shaders on all r3xx-r5xx hw. IIRC, MC was done with the 3D engine on older asics (r1xx/r2xx) as well, but there may have been some special bits in the pipeline to handle it due to the lack of shaders on the older hw.

I also happen to be a C developer with time on my hands (apart from WoW, which is like a black hole for free time) so what's the harm in a little extra functionality?

Your best bet would be to study the video decode math and see what could be done on the 3D engine. One of the Xorg GSoC students implemented an MC interface gallium. You might want to look at that.

[RobbieAB]

I don't think they actually had support for H.264 acceleration, neither in software nor hardware, only H.263 and maybe MPEG-4 ASP in addition to MPEG-2. Haven't used the driver myself though.

XvMC is a bit hit and miss on the Via chipsets as to whether the drivers support it or not. It is being actively worked on for the openChrome drivers...

[chrisr]

Your best bet would be to study the video decode math and see what could be done on the 3D engine. One of the Xorg GSoC students implemented an MC interface gallium. You might want to look at that.

Do you mean this?:
http://www.bitblit.org/gsoc/g3dvl/index.shtml

This seems to imply that MC was done using shaders for the Nouveau project. So assuming that shaders are ARB, and therefore portable between NVIDIA and ATI hardware, doesn't this imply that the video decode math is already done?

[bugmenot]

Yes, the idea is that it should be portable. The radeon-gallium3d-brach is just to incomplete to let the video decode run on it.

Also the video decoding via gallium3d has still some issues and missing features, look at the last blog entry. It is for example still too slow. Maybe you could help out there?