[FFmpeg-devel] Patch to WAV to accurately report duration

[Michael Niedermayer]

On Sat, Jan 15, 2011 at 02:16:05AM -0800, Frank Barchard wrote:
> On Wed, Jan 12, 2011 at 3:21 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
> 
> > On Wed, Jan 12, 2011 at 01:59:09PM -0800, Frank Barchard wrote:
> > > On Wed, Jan 12, 2011 at 8:04 AM, Michael Niedermayer <michaelni at gmx.at
> > >wrote:
> > >
> > > > On Mon, Jan 10, 2011 at 06:51:18PM -0800, Frank Barchard wrote:
> > > > > Patch to accurately report duration of a WAV.
> > > >
> > > > -    } else
> > > > > +    } else {
> > > > >          wav->data_end= url_ftell(pb) + size;
> > > > > +        st->nb_frames = size /
> > > > > +            (st->codec->channels * (st->codec->bits_per_coded_sample
> > >>
> > > > 3));
> > > > > +        st->duration = st->codec->frame_size ?
> > > > > +            st->nb_frames * st->codec->frame_size : st->nb_frames;
> > > > > +    }
> > > >
> > > > this is wrong, iam not even sure its guranteed to work with PCM
> > > >
> > >
> > > The patch has certainly worked for 8-bit, 16-bit, and 24-bit wav files
> > that
> > > we've tested.  With the patch, the number of frames is reported as
> > exactly
> > > right (as compared with the results returned by Apple's 'afinfo' tool).
> > >  Without the patch it is not accurate.
> >
> > try it with any VBR codec
> >
> 
> done.
> 
> This patch corrects VBR codecs, falling back on the estimate if
> bits_per_coded_sample is not set.
> 
> Also tested with mulaw and alaw that are fixed bits per sample.
> The intent of the math is to allow bits per sample that are not multples of
> 8

applied something less buggy, ill also add fact chunk support in a moment

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

Those who are too smart to engage in politics are punished by being
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