RFC: Video decode acceleration API
alexdeucher at gmail.com
Wed Mar 28 08:25:35 PDT 2007
On 3/28/07, Roderick Colenbrander <thunderbird2k at gmx.net> wrote:
> I wonder if we need a new extension at all. Modern videocards from ati/nvidia/s3 and perhaps intel too which support formats like mpeg4, vc-1 and others all utilize the fragment shader engine of the gpu. They don't have dedicated decoding hardware for specific compression schemes. Perhaps it is a smarter idea to implement such a library using lets say GLSL. You could have code which works on all cards with fragment shader support. (For modern card this is being worked on).
This doesn't help for older hardware or embedded processors that tend
to have dedicated video decoding capabilities but no or a limited 3D
engine. A GLSL backend might be a good option though for newer cards.
> Roderick Colenbrander
> > Hi,
> > Attached is a proposal for a video decode acceleration API that I would
> > like to get feedbacks from the X.org community. The main motivation for
> > this proposal is to enable hardware accelerated video decode at various
> > entry-points (VLD, IDCT, Motion Compensation etc.) for the prevailing
> > coding standards today (MPEG-2, MPEG-4, H.264/AVC and VC-1). After
> > looking at extending XvMC but due to its original design for MPEG-2
> > MotionComp only, it seems making more sense to design an interface from
> > scratch that can fully expose the video decode capabilities in today's
> > GPUs.
> > The current interface is focused on video decode only and is window
> > system independent, so that potentially it can be used with graphics
> > sub-systems other than X. In a nutshell it is basically a scheme to
> > pass various types of data buffers from the application to the GPU for
> > decoding a compressed bit-stream. This is very much a work-in-progress
> > and the current draft only defines data structures for MPEG-2 and VC-1
> > decode at the VLD (or slice level) entry-point. I would like to get
> > this out for critic and feedback before going too much further, and also
> > hopefully make it a community collaborative effort.
> > Thanks,
> > Jonathan Bian
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