[vlc-devel] [PATCH v4 1/7] libvlc: allow selecting the video hardware acceleration

Steve Lhomme robux4 at ycbcr.xyz
Mon Mar 16 10:09:19 CET 2020

On 2020-03-13 16:32, Rémi Denis-Courmont wrote:
> Le perjantaina 13. maaliskuuta 2020, 14.35.54 EET Steve Lhomme a écrit :
>> This time it's a string.
>> There's still no way to actually force NVDEC though. The nvdec decoder
>> has lower priority than lavc and therefore is never selected. The only
>> way to use it is to force --codec=nvdec.
>> Maybe we could give it a higher priority than lavc.
> If it's as fast to initialize as NVIDIA GL is (not), then hell no. It's taking
> seconds to start playback here, absolutely horrible UX. Don't double that.

This will only change the decoder priority, not the decoder device. The 
decoder doesn't load any DLLs. It asks for a decoder device and if 
that's the nvdec one it can be used. If not the next decoder (lavc) will 
be used which may request a decoder device which will be the same 
instance as loaded by nvdec.

It may be slowing down the startup for formats where lavc would have 
never used a decoder device in the first place. But in the nvcdec codec 
we already check the few codecs we support, if not supported we don't 
load any resources. So it should have no impact putting the nvdec codec 
with a higher priority.

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