On Mon, 24 Mar 2014 22:16:01 +0200, Rémi Denis-Courmont <[email protected]> wrote:
> Le lundi 24 mars 2014, 20:23:05 Anton Khirnov a écrit :
> > > Last I checked, libavcodec did not support hardware acceleration for
> > > anything other than 4:2:0 - just looking at the pixel format lists...
> > > Anyway, is there even *real* hardware slice-level decoder that supports
> > > 4:2:2? As far as I know, hardware video acceleration frameworks support
> > > 4:2:2 for post-processing and rendering, not (really yet) for decoding.
> > 
> > Just because we do not currently support them does not strike me as a good
> > reason to limit our API so we _cannot_ support them in the future.
> 
> The point is that currently those surface types are used by 4:2:0 surfaces 
> only. If support for 4:2:2 or Hi10p or whatever gets added to libavcodec, the 
> newly used surface types should be assigned new pixel formats, consistently 
> with the underlying acceleration APIs as well as with libavcodec software 
> pixel formats.
> 
> It would suck for applications to have to second-guess libavcodec.
> 

What would be the advantage in having separate pixel formats. A normal pixel
format tells you how is the data laid out in memory and how you are supposed to
inrepret it. A hwaccel pixel format just tells you that the data is outside the
scope of libav and you have to deal with it using a special external API. You
would still use the same API whether it's 8bit 420 or 10bit 444. So from the
point of view of libav it's still the same format.

-- 
Anton Khirnov
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