[vlc-devel] [PATCH 1/7] avcodec: va: pass the software format description to the VA

Rémi Denis-Courmont remi at remlab.net
Sat Oct 5 09:57:35 CEST 2019

Le lauantaina 5. lokakuuta 2019, 9.56.31 EEST Steve Lhomme a écrit :
> On 2019-10-04 16:26, Rémi Denis-Courmont wrote:
> > Hi,
> > 
> > Why does the decoder need to care? Isn't that a hassle for the RGB
> > conversion shader rather than the decoding??
> Hardware decoders can only decode certain profiles. If you're out of
> that profile it just won't work. In the case of HEVC the 4:2:2, 4:4:4
> and 12 bits support are all in a single "profile" (Range Extension). But
> that information alone doesn't tell much about what kind of output
> you're getting. And some hardware decoders (newer Intel CPUs in my case)
> only support some combination (no 12 bits for example, 4:2:2 only for 10
> bits). The only way to know the kind of output the decoder is going to
> require (and thus if the decoder can actually support the stream) is by
> getting the chroma subsampling from the pixel format.

How will this work for non-avcodec based (hardware) decoders? AFAICT, we don't 
have the chroma infos early enough for probing.


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