[FFmpeg-devel] hardware aided video decoding
Fri Jul 6 11:14:35 CEST 2007
Reimar D?ffinger wrote:
> On Fri, Jul 06, 2007 at 09:45:26AM +0200, Attila Kinali wrote:
>> In view of the slowly progressing open graphics project
>> I wanted to ask how the people here would accelerate video
>> decoding with help of the graphics card. Respectively,
>> what functions would you expect the graphics card to have
>> to help FFmpeg/lavc to decode video.
The kind of functions you may enjoy are related to the final decoding
steps, start from pixel conversion, move to scaling, stop at id*t. The
whole point is spare bandwidth along with cpu cycles.
> While I haven't tried hardware-supported H.264, the one for MPEG-2
> usually isn't much faster than all-CPU, and I think most of the speed
> advantage comes from less data being transferred of the bus.
> IMO if you want it to be flexible you can only do parts of the decoding
> like idct on the card, but that might often mean transferring the data
> in both directions, so unless you have PCIe you can just forget that.
should be avoided since most of the gfx design have very fast write and
painful slow read.
> My personal opinion: Don't bother. A faster CPU would be cheaper than a
> special chip on the graphics card. At most consider implementing the
> parts of OpenGL programmability that might be most useful for this
> first and maybe expose it also in a non-OpenGL way (though there is a
> simplified OpenGL even for embedded devices).
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