[FFmpeg-devel] [PATCH] avformat/movenc: add EAC3 muxing support.

[Benoit Fouet]

Hi,

----- Mail original -----
> Hi,
> 
> ----- Mail original -----
> > On Tue, Oct 07, 2014 at 03:02:38PM +0200, Benoit Fouet wrote:
> > > Support only one independent substream right now, and only
> > > syncframes
> > > containing 6 blocks.
> > > 
> > > Fixes part of ticket #3074
> > > ---
> > > 
> > > Right now, this produces the same output as the previous patch
> > > for
> > > supported
> > > streams, and rejects the unsupported ones.
> > > Support for syncframes concatenation will come afterwards.
> > > 
> > >  libavformat/isom.c   |   1 +
> > >  libavformat/movenc.c | 184
> > >  +++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  libavformat/movenc.h |   2 +
> > >  3 files changed, 187 insertions(+)
> > > 
> 
> [...]
> 
> > > diff --git a/libavformat/movenc.c b/libavformat/movenc.c
> > > index bfee866..18c5955 100644
> > > --- a/libavformat/movenc.c
> > > +++ b/libavformat/movenc.c
> 
> [...]
> 
> > > @@ -292,6 +293,178 @@ static int mov_write_ac3_tag(AVIOContext
> > > *pb,
> > > MOVTrack *track)
> 
> [...]
> 
> > > +static int handle_eac3(AVPacket *pkt, MOVTrack *track)
> > > +{
> > > +    GetBitContext gbc;
> > > +    AC3HeaderInfo tmp, *hdr = &tmp;
> > > +    struct eac3_info *info;
> > > +    int ret, num_blocks;
> > > +
> > > +    if (!track->eac3_priv && !(track->eac3_priv =
> > > av_mallocz(sizeof(*info))))
> > > +        return AVERROR(ENOMEM);
> > > +    info = track->eac3_priv;
> > > +
> > 
> > > +    init_get_bits(&gbc, pkt->data, pkt->size * 8);
> > > +    if ((ret = avpriv_ac3_parse_header2(&gbc, &hdr)) < 0)
> > > +        return ret;
> > 
> > [...]
> > > +                if ((ret = avpriv_ac3_parse_header2(&gbc, &hdr))
> > > <
> > > 0)
> > > +                    return ret;
> > 
> > these forward internal error codes like
> > AAC_AC3_PARSE_ERROR_FRAME_TYPE
> > to the lib user
> > av_strerror() for example will not be able to interpret these
> > 
> 
> True.
> 
> > also this would prevent remuxing a stream that contains a
> > single damaged packet if i understand correctly, this may be
> > annoying for sources recoded over somewhat noisy channels
> > 
> 
> Also true, though I'm not sure how to handle this. Dropping the
> packet would presumably be a way of dealing with this.
> Please note that the E-AC-3 stream passes through the E-AC-3 parser
> before muxing, so these errors shouldn't really happen in practice,
> except for the first frame (or maybe I missed something in the way
> the parser works?).
> A solution here could be to drop the packet if it is the first one,
> and error out if not (with an AV_ error code), what do you think?
> 
> > also how can this patch be tested ?
> > carls testcase from the ticket does not seem to work
> > 
> 
> If we drop the erroneous packet instead of erroring out, the testcase
> works fine.
> 

New patch attached, as reference.

-- 
Ben
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