[libav-devel] [PATCH 1/2] vdpau: add helper for surface chroma type

Rémi Denis-Courmont remi at remlab.net
Wed Sep 10 21:21:58 CEST 2014

Le mercredi 10 septembre 2014, 21:11:39 wm4 a écrit :
> On Wed, 10 Sep 2014 21:48:14 +0300
> Rémi Denis-Courmont <remi at remlab.net> wrote:
> > Le mercredi 10 septembre 2014, 20:39:50 wm4 a écrit :
> > > I think it would be better in terms of backwards compatibility to have
> > > the user call a function to signal support for formats other than
> > > VDP_CHROMA_TYPE_420. (Instead of the other way around and suddenly
> > > requiring every user to check for this.)
> > 
> > You and others refused to introduce a new pixel format, which is how that
> > would normally be solved. So now you get the breakage. I told you so.
> > 
> > I have wasted enough time with developers who cannot make their mind.
> Here's an example how to solve it in a backward compatible way:
> void av_vdpau_allow_chroma_type(AVCodecContext *avctx, VdpChromaType type);
> The application notifies libavcodec that it supports this chroma type.
> You haven't replied anything to our concerns about mapping DXVA pixel
> formats, so I can just continue to assume that mapping DXVA formats to
> libav pixel formats would be infeasible.

With that function, the application needs to make one call for each chroma 
type that it supports, and libavcodec needs to keep track of them (at best 
with a bit field).

So it is just as "infeasible". It's even worse than using pixel formats.

Rémi Denis-Courmont

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