[FFmpeg-devel] FFMPEG extension OpenCL

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sun Dec 11 10:46:03 CET 2011

On Sun, Dec 11, 2011 at 10:18:57AM +0100, madshi wrote:
> 2011/12/10 Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> > However I think there is OpenCL/OpenGL interoperability
> > that would mean no extra copying.
> Interop can't do magic. If you want a PCIe GPU to do the work,
> all the data must go through the PCIe bus at least twice. And
> some GPU drivers are optimized for that much better (NVidia)
> than others (AMD).

Huh? That would of course only help when you'd want to display
the thing at the end.
Yes, it would need a new "OpenGL texture" pixel format or such
otherwise we can't pass it through the filter chain.

> > Some scale filters can easily do these at the same time
> > and I think they can give better results than separate scale
> > and sharpening.
> I strongly disagree. I've implemented lots of image/video scaling
> algorithms and none of them were any good at noise reduction
> or sharpening. At least not compared to what a dedicated
> algorithm can do.

Ok, badly written. I meant there are combined algorithms that might
be "ok" and just might put a scale filter up enough in complexity
to make OpenCL worthwhile.
And then in principle a combined scale+sharpen will certainly be
able to do as well as separate ones, but it really should be able
to do better, since either the sharpening has to deal with stuff
introduced by scale or vice versa.
Whether there's any existing algorithm worth it is a different question.

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