On 28.05.2015 04:29, Michael Niedermayer wrote: > 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
Indeed. Fixed patch attached. Best regards, Andreas
>From 1ecae2a3b588c878f91b1c5c1cf93c2d9bc81812 Mon Sep 17 00:00:00 2001 From: Andreas Cadhalpun <andreas.cadhal...@googlemail.com> Date: Wed, 27 May 2015 23:57:50 +0200 Subject: [PATCH] mov: fix DTS calculation for samples with negative stts duration 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 | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/libavformat/mov.c b/libavformat/mov.c index 51cdd21..7ce5a86 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; @@ -2439,10 +2433,13 @@ 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 last_dts = 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); current_dts -= sc->dts_shift; + last_dts = current_dts; if (!sc->sample_count || st->nb_index_entries) return; @@ -2522,7 +2519,27 @@ static void mov_build_index(MOVContext *mov, AVStream *st) current_offset += sample_size; stream_size += sample_size; + + /* 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; + } current_dts += sc->stts_data[stts_index].duration; + if (current_dts + dts_correction > last_dts) { + current_dts += dts_correction; + dts_correction = 0; + } else { + /* Avoid creating non-monotonous DTS */ + dts_correction += current_dts - last_dts - 1; + current_dts = last_dts + 1; + } + last_dts = current_dts; distance++; stts_sample++; current_sample++; -- 2.1.4
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