[FFmpeg-devel] [PATCH] HWAccel infrastructure (take 7.1)

Reimar Döffinger Reimar.Doeffinger
Tue Feb 24 20:13:00 CET 2009

On Tue, Feb 24, 2009 at 07:43:21PM +0100, Gwenole Beauchesne wrote:
> Le 24 f?vr. 09 ? 18:08, Reimar D?ffinger a ?crit :
>> Not using per-codec PIX_FMTs seems more likely to me to just complicate
>> things, though I do not know for sure.
> It turned out the changes to my local mplayer tree were rather small. See 
> attachement + adding the extra codec_ids in the table.

I guess there are some changes it conversion_map missing?

> However, I terribly dislike the pixfmt2imgfmt() name as it is now implied 
> by the removal of codec information in pixfmt.

Well, IMO while it needs little changes that patch takes the
"move the mess one step higher" approach.
One particular disadvantage of that approach is that e.g. you can't see
if it would still be possible to "misuse" libswscale to convert between
VDPAU- and YV12-format without API changes.
There are also other questions like if it can cause any issues that
AVFrame + PIX_FMT is no longer sufficient to interpret the data
(obviously this can be solved e.g. by added a codec identifier to

>> In contrast, IMO per-level PIX_FMTs would have been a serious detriment
>> to future development and generally better hardware support (and I still
>> consider the usage of this stuff a serious misdesign in the accelration
>> APIs).
> Actually, some manufacturers use level information for error checking. 

With what purpose? Making sure that single-bit errors can break playback
even more thoroughly? :-P
It also means the decoder must be reinitialized on level changes. Not such
a big issue by itself, but it is hard to make playback smooth in that case.

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