On Thu, May 28, 2015 at 12:11:00AM +0200, Andreas Cadhalpun wrote: > A negative sample duration is invalid according to the spec, but there > are samples that use it for the DTS calculation, e.g.: > http://files.1f0.de/samples/mp4-negative-stts-problem.mp4 > > These currently get out of A/V sync. > > Also change the logging type to AV_LOG_WARNING, because decoding the > sample can continue. > > Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com> > --- > libavformat/mov.c | 20 ++++++++++++++------ > 1 file changed, 14 insertions(+), 6 deletions(-) > > diff --git a/libavformat/mov.c b/libavformat/mov.c > index 51cdd21..730f097 100644 > --- a/libavformat/mov.c > +++ b/libavformat/mov.c > @@ -2234,12 +2234,6 @@ static int mov_read_stts(MOVContext *c, AVIOContext > *pb, MOVAtom atom) > sample_count=avio_rb32(pb); > sample_duration = avio_rb32(pb); > > - /* sample_duration < 0 is invalid based on the spec */ > - if (sample_duration < 0) { > - av_log(c->fc, AV_LOG_ERROR, "Invalid SampleDelta %d in STTS, at > %d st:%d\n", > - sample_duration, i, c->fc->nb_streams-1); > - sample_duration = 1; > - } > if (sample_count < 0) { > av_log(c->fc, AV_LOG_ERROR, "Invalid sample_count=%d\n", > sample_count); > return AVERROR_INVALIDDATA; > @@ -2439,6 +2433,7 @@ static void mov_build_index(MOVContext *mov, AVStream > *st) > unsigned int distance = 0; > unsigned int rap_group_index = 0; > unsigned int rap_group_sample = 0; > + int64_t dts_correction = 0; > int rap_group_present = sc->rap_group_count && sc->rap_group; > int key_off = (sc->keyframe_count && sc->keyframes[0] > 0) || > (sc->stps_count && sc->stps_data[0] > 0); > > @@ -2522,6 +2517,19 @@ static void mov_build_index(MOVContext *mov, AVStream > *st) > > current_offset += sample_size; > stream_size += sample_size; > + current_dts += dts_correction;
i think this could depending on the next stts value end up making
DTS non monotone which seems wrong/unintended
> + /* A negative sample duration is invalid based on the spec,
> + * but some samples need it to correct the DTS. */
> + if (sc->stts_data[stts_index].duration < 0) {
> + av_log(mov->fc, AV_LOG_WARNING,
> + "Invalid SampleDelta %d in STTS, at %d st:%d\n",
> + sc->stts_data[stts_index].duration, stts_index,
> + st->index);
> + dts_correction = sc->stts_data[stts_index].duration - 1;
> + sc->stts_data[stts_index].duration = 1;
> + } else {
> + dts_correction = 0;
> + }
> current_dts += sc->stts_data[stts_index].duration;
> distance++;
> stts_sample++;
> --
> 2.1.4
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Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
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