[FFmpeg-user] is ffmpeg using gpu???

[Rick C.]

> On Jan 11, 2015, at 10:00 PM, Andy Furniss <adf.lists at gmail.com> wrote:
> 
> Moritz Barsnick wrote:
>> On Sun, Jan 11, 2015 at 17:22:39 +0800, Rick C. wrote:
>> 
>>> Can it be used though to speed things up?  If so what command would
>>> I need to use? Thanks again for the help...
>> 
>> May I point you to this thread and particular mail on this list:
>> https://ffmpeg.org/pipermail/ffmpeg-user/2013-August/016698.html
>> 
>> It only relates to OpenCL, I don't know if ffmpeg supports any other
>> methods of using a GPU.
> 
> On Linux if your GPU has h/w decode and the input file is the right type
> ffmpeg can use that.
> 
> For me the command would be -
> 
> ffmpeg -hwaccel vdpau -i infile ...
> 
> It may not gain you much though as GPUs decode are designed for playing
> rather than going as fast as they can, there is also mention somewhere
> of having to read back the yuv reducing the gain. Maybe if you have a
> slow CPU then the reduced decode load will free more for the encode.
> 
> On my 4x3.4GHz box there wasn't much difference IIRC.
> 
> Just testing GPU vs s/w for bluray decode the CPU was way faster - as
> expected I guess.
> 
>> In this thread, Tom notes:
>>> Generally the consensus (at least on here, as far as I can tell)
>>> is that GPU assisted encoding is slow and gives crap results.
>>> YMMV.
> 
> 
> Not the same thing but there is a way to get libx264 to use some opencl, though I don't know
> what it's like as my radeonsi opencl isn't yet a complete enough
> implementation to work.
> 
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Thanks all for the help I will look into this...