[FFmpeg-devel] [PATCH 3/6] lavc: deprecate -ab as part of FF_API_OLD_AVOPTIONS.

Michael Niedermayer michael at niedermayer.cc
Tue Aug 18 03:56:21 CEST 2015


On Mon, Aug 17, 2015 at 01:38:19PM -0400, Ronald S. Bultje wrote:
> Hi,
> 
> On Mon, Aug 17, 2015 at 1:12 PM, Michael Niedermayer <michael at niedermayer.cc
> > wrote:
> 
> > On Mon, Aug 17, 2015 at 11:52:16AM -0400, Ronald S. Bultje wrote:
> > > ---
> > >  libavcodec/options_table.h | 2 ++
> > >  1 file changed, 2 insertions(+)
> >
> > googling for
> > ffmpeg "-ab"
> > has 332.000 matches
> >
> > ffmpeg "-b:a"
> > has 64.100 matches
> >
> > this patch is simply a bad idea
> 
> 
> So, there's a few practical problems here. A) if we remove flag/mask from
> the set_defaults calls (other patch in this set), the audio is also used
> for the video ones (since we ignore media type), and thus we use (after
> FF_API_OLD_AVOPTIONS is 0) the audio bitrate as default for video also.
> That's bad, and causes some fate failures. We can workaround that by
> inverting the ordering of these two, but then, the general one _always_
> (even before FF_API_OLD_AVOPTIONS=0) takes precedence over the audio one,
> so all fate results without explicit bitrate change from ab=128k to
> ab=200k. (I'm working around that by making each fate test set bitrate
> explicit where relevant.)
> 

> Alternate suggestion: I don't mind if -ab gets a workaround in ffmpeg.c,
> but I'd like to remove it from the libav* code.

ffserver seems to have "ab" hardcoded in
ffserver_config.c
this will need some change too, i dont know the code so i dont know
what needs to be done / if a simple change to "b" is sufficient
it seems to work with "b" better than with "ab" though after
FF_API_OLD_AVOPTIONS=0)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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