[FFmpeg-devel] [PATCH] Try to make new VDPAU usable by adding context to callback.

Michael Niedermayer michaelni at gmx.at
Thu Aug 8 15:29:57 CEST 2013

On Thu, Aug 08, 2013 at 04:02:11AM +0200, Reimar Döffinger wrote:
> On 07.08.2013, at 23:44, Michael Niedermayer <michaelni at gmx.at> wrote:
> > A function to allocate a AVVDPAUContext is needed to allow future
> > extension i think (arguable this is orthogonal to this patch)
> > 
> > A function to set/get the render2 field is needed so as to allow
> > multiple forks to add fields to the structure without breaking ABI
> > 
> I expected that comment, and it feels like a rather insane amount of effort.

its like 3 lines of code ...

> The reason why I proposed it is that no fork can really add anything without a major bump anyway, so while doing all this would have been the only reasonable way in the first place,


> I'm not convinced it makes a difference now...

now, maybe not but it can make a difference in the future
lets just assume that libav fixes the ABI issue.
if you use direct access then we will need a major bump on every
change while libav will not on the corresponding addition of fields

If you use the wrapers not only can we add, remove, change and move
our fields without major ABI bumps, we also dont have issues if libav
fixes their side and adds fields

> > iam not sure if this or a function ptr in AVCodecContext is
> > simpler/better
> The problem there is the use of vdpau types (though to be honest just using unsigned and void * instead should work fine), though due to the hwaccel mess I think it would be better.
> But there are lots of details, for example I think it would make sense to make it a union to allow sonething similar for the other hwaccels, but I don't know how that would work with the accessors.
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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