[FFmpeg-devel] [PATCH] lavf/mov.c: Use the first sidx for tracks without sidx.

[Sasi Inguva]

Fixes audio stream duration of the attached mp4f file.
Without this patch , .
/ffprobe -show_streams h264_aac_6sec.mp4
audio duration is determined as 2s. because there is no sidx for that
stream. With this patch it stream duration is 6s.

On Tue, Oct 25, 2016 at 11:07 PM, Sasi Inguva <isasi at google.com> wrote:

> According to spec ISO_IEC_15444_12 "For any media stream for which no
> segment index is present, referred to as non‐indexed stream, the media
> stream associated with the first Segment Index box in the segment serves as
> a reference stream in a sense that it also describes the subsegments for
> any non‐indexed media stream."
>
> Signed-off-by: Sasi Inguva <isasi at google.com>
> ---
>  libavformat/isom.h |  1 +
>  libavformat/mov.c  | 26 +++++++++++++++++++++++---
>  2 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index 9038057..d684502 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -179,6 +179,7 @@ typedef struct MOVStreamContext {
>      int32_t *display_matrix;
>      uint32_t format;
>
> +    int has_sidx;  // If there is an sidx entry for this stream.
>      struct {
>          int use_subsamples;
>          uint8_t* auxiliary_info;
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 357d800..1b04b1a 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -4189,6 +4189,7 @@ static int mov_read_trun(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
>
>      frag->implicit_offset = offset;
>
> +    av_log(c, AV_LOG_DEBUG, "stindex: %d duration: %d end: %d\n",
> st->index, st->duration, sc->track_end);
>      sc->track_end = dts + sc->time_offset;
>      if (st->duration < sc->track_end)
>          st->duration = sc->track_end;
> @@ -4202,7 +4203,8 @@ static int mov_read_sidx(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
>      uint8_t version;
>      unsigned i, track_id;
>      AVStream *st = NULL;
> -    MOVStreamContext *sc;
> +    AVStream *ref_st;
> +    MOVStreamContext *sc, *ref_sc;
>      MOVFragmentIndex *index = NULL;
>      MOVFragmentIndex **tmp;
>      AVRational timescale;
> @@ -4284,9 +4286,26 @@ static int mov_read_sidx(MOVContext *c, AVIOContext
> *pb, MOVAtom atom)
>
>      c->fragment_index_data = tmp;
>      c->fragment_index_data[c->fragment_index_count++] = index;
> +    sc->has_sidx = 1;
> +
> +    if (offset == avio_size(pb)) {
> +        for (i = 0; i < c->fc->nb_streams; i++) {
> +            if (c->fc->streams[i]->id == c->fragment_index_data[0]->track_id)
> {
> +                ref_st = c->fc->streams[i];
> +                ref_sc = ref_st->priv_data;
> +                break;
> +            }
> +        }
> +        for (i = 0; i < c->fc->nb_streams; i++) {
> +            st = c->fc->streams[i];
> +            sc = st->priv_data;
> +            if (!sc->has_sidx) {
> +                st->duration = sc->track_end =
> av_rescale(ref_st->duration, sc->time_scale, ref_sc->time_scale);
> +            }
> +        }
>
> -    if (offset == avio_size(pb))
>          c->fragment_index_complete = 1;
> +    }
>
>      return 0;
>  }
> @@ -5846,13 +5865,14 @@ static int mov_read_packet(AVFormatContext *s,
> AVPacket *pkt)
>  static int mov_seek_fragment(AVFormatContext *s, AVStream *st, int64_t
> timestamp)
>  {
>      MOVContext *mov = s->priv_data;
> +    MOVStreamContext *sc = st->priv_data;
>      int i, j;
>
>      if (!mov->fragment_index_complete)
>          return 0;
>
>      for (i = 0; i < mov->fragment_index_count; i++) {
> -        if (mov->fragment_index_data[i]->track_id == st->id) {
> +        if (mov->fragment_index_data[i]->track_id == st->id ||
> !sc->has_sidx) {
>              MOVFragmentIndex *index = mov->fragment_index_data[i];
>              for (j = index->item_count - 1; j >= 0; j--) {
>                  if (index->items[j].time <= timestamp) {
> --
> 2.8.0.rc3.226.g39d4020
>
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: h264_aac_6sec.mp4
Type: video/mp4
Size: 1170721 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20161025/ff1e1749/attachment.mp4>