[FFmpeg-devel] [PATCH v2 2/2] ogg/{vorbis, flac, opus}: Remove header packets from subsequent ogg streams from the demuxer output.

[Michael Niedermayer]

Hi Romain

On Tue, Apr 29, 2025 at 05:42:22PM -0500, Romain Beauxis wrote:
> Le mar. 29 avr. 2025 à 16:35, Michael Niedermayer
> <michael at niedermayer.cc> a écrit :
> >
> > Hi
> >
> > On Mon, Apr 28, 2025 at 06:31:36PM -0500, Romain Beauxis wrote:
> > > ---
> > >  libavformat/oggdec.c                       | 26 ++++++++++----------
> > >  libavformat/oggdec.h                       |  6 +++++
> > >  libavformat/oggparseflac.c                 | 28 ++++++++++++++++++++--
> > >  libavformat/oggparseopus.c                 | 12 ++++++++++
> > >  libavformat/oggparsevorbis.c               | 12 ++++++++--
> > >  tests/ref/fate/ogg-flac-chained-meta.txt   |  2 --
> > >  tests/ref/fate/ogg-opus-chained-meta.txt   |  1 -
> > >  tests/ref/fate/ogg-vorbis-chained-meta.txt |  3 ---
> > >  8 files changed, 68 insertions(+), 22 deletions(-)
> > >
> > > diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
> > > index 5339fdd32c..5557eb4a14 100644
> > > --- a/libavformat/oggdec.c
> > > +++ b/libavformat/oggdec.c
> > > @@ -239,10 +239,6 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, char *magic,
> > >      os->start_trimming = 0;
> > >      os->end_trimming = 0;
> > >
> > > -    /* Chained files have extradata as a new packet */
> > > -    if (codec == &ff_opus_codec)
> > > -        os->header = -1;
> > > -
> > >      return i;
> > >  }
> > >
> > > @@ -605,20 +601,26 @@ static int ogg_packet(AVFormatContext *s, int *sid, int *dstart, int *dsize,
> > >      } else {
> > >          os->pflags    = 0;
> > >          os->pduration = 0;
> > > +
> > > +        ret = 0;
> > >          if (os->codec && os->codec->packet) {
> > >              if ((ret = os->codec->packet(s, idx)) < 0) {
> > >                  av_log(s, AV_LOG_ERROR, "Packet processing failed: %s\n", av_err2str(ret));
> > >                  return ret;
> > >              }
> > >          }
> > > -        if (sid)
> > > -            *sid = idx;
> > > -        if (dstart)
> > > -            *dstart = os->pstart;
> > > -        if (dsize)
> > > -            *dsize = os->psize;
> > > -        if (fpos)
> > > -            *fpos = os->sync_pos;
> > > +
> > > +        if (!ret) {
> > > +            if (sid)
> > > +                *sid = idx;
> > > +            if (dstart)
> > > +                *dstart = os->pstart;
> > > +            if (dsize)
> > > +                *dsize = os->psize;
> > > +            if (fpos)
> > > +                *fpos = os->sync_pos;
> > > +        }
> > > +
> > >          os->pstart  += os->psize;
> > >          os->psize    = 0;
> > >          if(os->pstart == os->bufpos)
> >
> > > diff --git a/libavformat/oggdec.h b/libavformat/oggdec.h
> > > index 43df23f4cb..09f698f99a 100644
> > > --- a/libavformat/oggdec.h
> > > +++ b/libavformat/oggdec.h
> > > @@ -38,6 +38,12 @@ struct ogg_codec {
> > >       *         -1 if an error occurred or for unsupported stream
> > >       */
> > >      int (*header)(AVFormatContext *, int);
> > > +    /**
> > > +     * Attempt to process a packet as a data packet
> > > +     * @return 1 if the packet was a header from a chained bitstream.
> > > +     *         0 if the packet was a regular data packet.
> > > +     *         -1 if an error occurred or for unsupported stream
> > > +     */
> > >      int (*packet)(AVFormatContext *, int);
> > >      /**
> > >       * Translate a granule into a timestamp.
> >
> > ok, but seems unrelated
> 
> This is a new convention to allow the parser to know when to skip a
> packet. Previous to that, return value of 1 did not have specific
> meaning.

Do you think this would merit a seperate patch ?
I mean patch #1 changing the packet() return value and clearly stating
that in the commit message
and patch #2 using the new value ?

I think it would make things clearer

thx

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

The bravest are surely those who have the clearest vision
of what is before them, glory and danger alike, and yet
notwithstanding go out to meet it. -- Thucydides
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