[FFmpeg-devel] [PATCH] HWAccel infrastructure (take 5)

Reimar Döffinger Reimar.Doeffinger
Fri Feb 20 19:25:53 CET 2009

On Fri, Feb 20, 2009 at 06:33:08PM +0100, Michael Niedermayer wrote:
> the list you get from lavc really should be best to worst so picking the
> first you support should work in general.

Particularly with hardware-decoding, I don't think you will get everyone
to agree which is "best".

> And i really dont see how adding a hw accel format in front can break
> any half sane written app. We also could add another new non hw pix_fmt
> in front and a app must not choose this unless it supports it ...

Well, they might have taken a hint for default_get_format and concluded
that the first one is "the best", where they defined "best" as "most
widely supported". I could imagine someone falling back to that format
just because they did not want to implement full building/destroying of
a whole filter chain including format conversion filter insertion for
testing every format. "See if some format is obviously better, otherwise
use the first and beat it to work" for me qualifies as sloppy/lazy, but
not as "not sane".
But mostly it is a question of how to define "the best" format, and I
would have disqualified hardware decoders (particularly for MPEG2)
because they have little error concealment, some errors may cause severe
system problems (too much code running as root/blocking the display
device) and simply not handling some streams. None of these are
properties inherent to the pixfmts though, just the current decoder

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