[FFmpeg-devel] [PATCH 1/2] lavf: add AVOption support for muxers

[Michael Niedermayer]

On Sat, Jan 01, 2011 at 06:15:08PM +0200, Martin Storsj? wrote:
> On Sat, 1 Jan 2011, Michael Niedermayer wrote:
> 
> > On Sat, Jan 01, 2011 at 06:44:55AM +0200, Anssi Hannula wrote:
> > > On 29.12.2010 14:19, Stefano Sabatini wrote:
> > > > On date Wednesday 2010-12-29 13:58:00 +0200, Anssi Hannula encoded:
> > > >> On 29.12.2010 13:40, Stefano Sabatini wrote:
> > > >>> On date Wednesday 2010-12-29 06:54:14 +0200, Anssi Hannula encoded:
> > > >>>> ---
> > > >>>>  libavformat/avformat.h |    2 ++
> > > >>>>  libavformat/utils.c    |    4 ++++
> > > >>>>  2 files changed, 6 insertions(+), 0 deletions(-)
> > > >>>>
> > > >>>> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> > > >>>> index c6f2827..9eab2da 100644
> > > >>>> --- a/libavformat/avformat.h
> > > >>>> +++ b/libavformat/avformat.h
> > > >>>> @@ -368,6 +368,8 @@ typedef struct AVOutputFormat {
> > > >>>>      const AVMetadataConv *metadata_conv;
> > > >>>>  #endif
> > > >>>>  
> > > >>>> +    const AVClass *priv_class; ///< AVClass for the private context
> > > >>>> +
> > > >>>>      /* private fields */
> > > >>>>      struct AVOutputFormat *next;
> > > >>>>  } AVOutputFormat;
> > > >>>
> > > >>> Put this after the "next" field or it will break ABI (note for the
> > > >>> committer: bump minor).
> > > >>
> > > >> Well, I thought the /* private fields */ meant that the lavf internal
> > > >> variables are last so that they can be added/removed/modified at will
> > > >> without breaking ABI, which only works if they indeed are the last ones.
> > > >>
> > > >> But if that is not the intention, priv_class can be put last (it is public).
> > > > 
> > > > If the "next" field is not used outside lavf then it should be safe to
> > > > keep it at the end of the struct.
> > > 
> > > Well, it shouldn't be, but we can't be sure.
> > > 
> > > I guess the question is, do we care if applications wrongly using it
> > > break? (I don't know the answer to this)
> > 
> > applications using private fields are writtenm in the knowledge that they will
> > stop working the next commit to ffmpeg
> 
> What about applications registering muxers/demuxers of their own? In that 

They should submit them to us and not do that :)
That said iam not against keeping the next parameter at a constant location
i just dont care too much about it

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

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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