[Mesa-dev] GSoC : Video decoding state tracker for Gallium3d

Alex Deucher alexdeucher at gmail.com
Sat Mar 26 09:53:38 PDT 2011

On Fri, Mar 25, 2011 at 5:44 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Wed, Mar 23, 2011 at 4:28 PM, ★ Emeric <emeric.grange at gmail.com> wrote:
>> Hi everyone,
>> My name is Emeric, I am a 22 years old french student, and I am
>> currently looking to apply to the google summer of code 2011.
>> I saw the "Gallium H.264 decoding" idea on the X.Org GSoC page, and I
>> am particularly interested by this project.
> A couple days ago, a few developer talked in passing about this idea
> on IRC. One point made was that shader-based video is kind of, well,
> not ideal, for cards that have dedicated hardware since it's going to
> utilize most of the cards resources and also use quite a bit of power
> in the process. Now, shaders may be the best we can do in practice,
> given the difficulties in releasing documentation for AMD's UVD, for
> instance, but still.

Has anyone actually compared power utilization on this?  It still
might be less or comparable to doing the decode on the CPU.  We still
use the 3D engine for the render portion of the decode even with
dedicated decode hardware.  Plus, on AMD hardware at least, on
r1xx-r5xx asics we didn't have UVD so we used the 3D engine for video
decode and it worked well, even on mobile asics.

> Since Google (and most of the free software community) is pushing WebM
> over H264, it might be a good idea to focus instead of WebM. Clearly
> there are no cards today that support WebM video decoding, so this
> would be neat. I don't know, but I'd guess a lot of the code needed
> for WebM decoding is also useful for H264 decoding.

WebM would definitely be cool.


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