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;
+ /* 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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