[vlc-devel] nvdec GPU to CPU converter

Jean-Baptiste Kempf jb at videolan.org
Tue Mar 3 10:39:52 CET 2020


On Tue, Mar 3, 2020, at 09:50, Quentin Chateau wrote:
> >>  1. Do you see any reason to keep the GPU-to-CPU video filter ?
> >
> > Yes. Even if the initial playback is using the GPU output, the user 
> > may add a CPU based filter during playback and a conversion will be 
> > required. The decoder will know nothing about that and will not change 
> > its output.
> Oh indeed, I did not think about changes during playback.

Or just a CPU filter required to be applied.

> >>  2. I think a --nvdec-prefer-opaque/--no-nvdec-prefer-opaque could be a
> >>     good addition if one knows in advance which chroma type will be
> >>     used. This would avoid the wall of error logs in certain
> >>     circumstances. What do you think ?
> >
> > The software output from the decoder only exists as a convenience. In 
> > an ideal world the decoder should only output NVDEC chromas and the 
> > conversion be done elsewhere. Maybe we can remove that part now that 
> > the push model is (mostly) done.
> I also agree the CPU fallback of the decoder can be removed. To be fair, 

Please do.

> Not sure where you guys stand on that, the only drawback is the extra 
> GPU/GPU copy compared to a direct CPU output. Although looking at the 
> code, we may even be able to get rid of that.

Please remove. "memcpy is murder"©®

Jean-Baptiste Kempf -  President
+33 672 704 734

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