[FFmpeg-devel] [PATCH] Function to parse Dirac sequence header
Thu Nov 13 04:00:07 CET 2008
On Tue, 2008-11-11 at 04:28 -0500, David Conrad wrote:
> On Nov 9, 2008, at 4:29 AM, Michael Niedermayer wrote:
> > On Wed, Nov 05, 2008 at 11:22:01PM -0500, David Conrad wrote:
> >> Hi,
> >> This will be useful for both the dirac parser and ogg demuxer (and
> >> future
> >> native dirac decoder of course.)
> >> Adapted from the soc repository.
> > I think the parser should not need this, av_find_stream_info()
> > should call
> > the decoder to fill in missing information. That assumes there is a
> > decoder
> > that does set it ...
> > about the ogg demuxer iam not sure if its needed or not ...
> The problem with ogg is that the only place the stream time_base is
> stored is in a codec-dependent way. Theora, FLAC, and Vorbis also have
> to parse their first setup packet to find this, the difference is that
> they don't use vlc and default tables so it's just simple reads at
> known offsets.
> The decoder will set the time_base in AVCodecContext, but I'm not sure
> how the time_base in AVStream would get set correctly if the demuxer
> doesn't set it.
This is what I am doing in my local tree.
st->need_parsing = AVSTREAM_PARSE_HEADERS;
( This ensures that the decoder is invoked during av_find_stream_info
if (st->codec->time_base.num && st->codec->time_base.den)
st->time_base = st->codec->time_base;
It appears to be an overkill to check the codec timebase and set the
stream time base in every call to ffdirac_gptopts, but the check is
required if we don't want to decode the Dirac sequence header in
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