On Fri, Feb 24, 2017 at 9:24 PM, John Stebbins <[email protected]>
wrote:
> Only the first entry in the edit list was factored into the time_offset
> of the first sample in a track. But when there is a delay (empty edit
> entry) the mediatime from the second entry must also be factored into
> the time_offset.
> ---
> libavformat/isom.h | 2 ++
> libavformat/mov.c | 30 ++++++++++++++++++++++--------
> 2 files changed, 24 insertions(+), 8 deletions(-)
>
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index 8cc5ab7..7c345e9 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -125,6 +125,8 @@ typedef struct MOVStreamContext {
> int *keyframes;
> int time_scale;
> int64_t time_offset; ///< time offset of the first edit list entry
> + int64_t time_offset_delay;
> + int64_t time_offset_skip;
> int current_sample;
> unsigned int bytes_per_frame;
> unsigned int samples_per_frame;
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 5c9f85c..1657647 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -2323,10 +2323,10 @@ static void mov_build_index(MOVContext *mov,
> AVStream *st)
> uint64_t stream_size = 0;
>
> /* adjust first dts according to edit list */
> - if (sc->time_offset && mov->time_scale > 0) {
> - if (sc->time_offset < 0)
> - sc->time_offset = av_rescale(sc->time_offset, sc->time_scale,
> mov->time_scale);
> - current_dts = -sc->time_offset;
> + if (mov->time_scale > 0) {
> + sc->time_offset = av_rescale(sc->time_offset_delay,
> sc->time_scale,
> + mov->time_scale) -
> sc->time_offset_skip;
> + current_dts = sc->time_offset;
> }
>
> /* only use old uncompressed audio chunk demuxing when stts specifies
> it */
> @@ -2999,6 +2999,10 @@ static int mov_read_trun(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
> sc = st->priv_data;
> if (sc->pseudo_stream_id+1 != frag->stsd_id)
> return 0;
> + if (c->time_scale > 0) {
> + sc->time_offset = av_rescale(sc->time_offset_delay,
> sc->time_scale,
> + c->time_scale) -
> sc->time_offset_skip;
> + }
> avio_r8(pb); /* version */
> flags = avio_rb24(pb);
> entries = avio_rb32(pb);
> @@ -3029,7 +3033,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
> }
> if (flags & MOV_TRUN_DATA_OFFSET) data_offset =
> avio_rb32(pb);
> if (flags & MOV_TRUN_FIRST_SAMPLE_FLAGS) first_sample_flags =
> avio_rb32(pb);
> - dts = sc->track_end - sc->time_offset;
> + dts = sc->track_end + sc->time_offset;
> offset = frag->base_data_offset + data_offset;
> distance = 0;
> av_log(c->fc, AV_LOG_TRACE, "first sample flags 0x%x\n",
> first_sample_flags);
> @@ -3069,7 +3073,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
> return AVERROR_EOF;
>
> frag->implicit_offset = offset;
> - st->duration = sc->track_end = dts + sc->time_offset;
> + st->duration = sc->track_end = dts - sc->time_offset;
> return 0;
> }
>
> @@ -3152,6 +3156,7 @@ static int mov_read_elst(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
> {
> MOVStreamContext *sc;
> int i, edit_count, version;
> + int time_offset_done = 0;
>
> if (c->fc->nb_streams < 1)
> return 0;
> @@ -3175,8 +3180,17 @@ static int mov_read_elst(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
> time = (int32_t)avio_rb32(pb); /* media time */
> }
> avio_rb32(pb); /* Media rate */
> - if (i == 0 && time >= -1) {
> - sc->time_offset = time != -1 ? time : -duration;
> + if (!time_offset_done) {
> + if (time == -1) {
> + /* delay is in movie timescale */
> + sc->time_offset_delay += duration;
> + } else if (time >= 0) {
> + /* samples to skip is in track timescale */
> + sc->time_offset_skip = time;
> + time_offset_done = 1;
> + }
> + /* timescales may not be known yet, so we can not compute
> + * a single combined time_offset yet */
> }
> }
>
> --
> 2.9.3
>
do you by any chance know if that fixes an issue with open-gop XDCAM? I
haven't gotten to making a bug report but the recent big edit list changes
have introduced a regression there for us (causing a/v desync when remuxing
such files). I will probably test this again anyway but was curious if that
was the motivation for the patch.
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