[FFmpeg-devel] [PATCH 1/5] avformat: Adding accessors for externally used AVStream fields which are after the public field list

[Michael Niedermayer]

On Wed, Jun 29, 2016 at 10:28:27PM +0200, Hendrik Leppkes wrote:
> On Wed, Jun 29, 2016 at 10:18 PM, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> > On Wed, Jun 29, 2016 at 09:41:50PM +0200, Clément Bœsch wrote:
> >> On Wed, Jun 29, 2016 at 09:36:39PM +0200, Michael Niedermayer wrote:
> >> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> >> > ---
> >> >  libavformat/avformat.h |    4 ++++
> >> >  libavformat/utils.c    |   21 +++++++++++++++++++++
> >> >  2 files changed, 25 insertions(+)
> >> >
> >> > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> >> > index 876f1e3..89f014b 100644
> >> > --- a/libavformat/avformat.h
> >> > +++ b/libavformat/avformat.h
> >> > @@ -1224,6 +1224,10 @@ void       av_stream_set_r_frame_rate(AVStream *s, AVRational r);
> >> >  struct AVCodecParserContext *av_stream_get_parser(const AVStream *s);
> >> >  char* av_stream_get_recommended_encoder_configuration(const AVStream *s);
> >> >  void  av_stream_set_recommended_encoder_configuration(AVStream *s, char *configuration);
> >> > +int64_t av_stream_get_cur_dts(AVStream *s);
> >> > +int64_t av_stream_get_first_dts(AVStream *s);
> >> > +int av_stream_get_pts_wrap_bits(AVStream *s);
> >> > +int64_t av_stream_get_codec_info_nb_frames(AVStream *s);
> >> >
> >> >  /**
> >> >   * Returns the pts of the last muxed packet + its duration
> >> > diff --git a/libavformat/utils.c b/libavformat/utils.c
> >> > index 6f343f2..5168816 100644
> >> > --- a/libavformat/utils.c
> >> > +++ b/libavformat/utils.c
> >> > @@ -132,6 +132,27 @@ struct AVCodecParserContext *av_stream_get_parser(const AVStream *st)
> >> >      return st->parser;
> >> >  }
> >> >
> >> > +int64_t av_stream_get_cur_dts(AVStream *s)
> >> > +{
> >> > +    return s->cur_dts;
> >> > +}
> >> > +
> >> > +int64_t av_stream_get_first_dts(AVStream *s)
> >> > +{
> >> > +    return s->first_dts;
> >> > +}
> >> > +
> >> > +int av_stream_get_pts_wrap_bits(AVStream *s)
> >> > +{
> >> > +    return s->pts_wrap_bits;
> >> > +}
> >> > +
> >> > +int64_t av_stream_get_codec_info_nb_frames(AVStream *s)
> >> > +{
> >> > +    return s->codec_info_nb_frames;
> >> > +}
> >> > +
> >> > +
> >>
> >> erm. how about we move them in the public fields instead?
> >
> > The 3.0 release has these fields in one location, the 3.1 release
> > has them in a different location because codecpar was added in the
> > middle. The fields are marked as private
> >
> > To fix this we can either as in this patchset add accessors and
> > use
> > them in all applications (probably not just ours)
> >
> > OR
> >
> > we could move codecpar to the end of AVStream
> >
> > OR
> >
> > we could bump major abi version
> >
> > what do people prefer ?
> >
> > moving them into the pblic fields will not make them match where
> > they where in 3.0, which is the problem  we have
> >
> 
> They are already in the wrong position, and they are marked explicitly
> as private fields, so any app using them is doing it wrong, we should
> not break the actual public ABI to cater to that.
> Moving codecpar now seems like a bad solution, as in contrast to these
> fields, codecpar is full public API/ABI and is in a release already
> (even if its only a few days old).
> 

> Adding new accessors will also not fix those old apps, since old
> ffmpeg wouldnt have the accessor,

Backporting the accessors is very simple


> so its no better then any other
> solution, and since we stopped caring about ABI compat with libav, the
> primary reason for them has also vanished.
> So I would vote for moving private fields that should be public right
> above the private marker and be done with it.

As this doesnt solve the ABI problem it would not help with this issue
or the distributions who want (but cannot) ship FFmpeg 3.1

Please tell me how you prefer the ABI issue with 3.0 / 3.1 to be
fixed

[...]

-- 
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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20160629/401c73f0/attachment.sig>