[FFmpeg-devel] FFMPEG extension OpenCL

madshi madshi at gmail.com
Sun Dec 11 11:08:06 CET 2011

2011/12/11 Reimar Döffinger <Reimar.Doeffinger at gmx.de>
> 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.

Not sure what you mean. OpenCL can run on the CPU,
but the real purpose of OpenCL (in my book) is to run
stuff on the GPU. If you have a PCIe GPU then you can't
expect the GPU/OpenCL do take over the work if the video
data is still in System RAM. So copying the data over the
PCIe bus can't be avoided.

> 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.

I have my doubts about that. If you look at this from a
scientific approach, during image *down*sampling you
first low pass filter the image (the usual linear resamplers
do that implicitly). Consequently, for upscaling you first
interpolate, then you try to "undo"  the low pass filter.
Two different things, really.

Practically, I don't know any algorithm out there which
which does scaling + sharpening integrated in good quality.
The best scaling and sharpening algorithms that I know of
are all separate algorithms (see e.g. AviSynth NNEDI3 and

Best regards, Mathias.

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