[FFmpeg-devel] [PATCH 1/4] avformat/matroskaenc: Allow to set multiple streams as default

[Andreas Rheinhardt]

Andreas Rheinhardt:
> The Matroska specifications have evolved and now allow to mark
> multiple tracks of the same kind as default (whether this was legal or
> not before was dubious; e.g. mkvmerge disallowed it). Yet when the
> Matroska muxer is set to infer default dispositions if absent, it also
> enforced the now outdated restriction. So update this.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>  doc/muxers.texi                               | 12 ++++++------
>  libavformat/matroskaenc.c                     | 16 ++++++----------
>  tests/ref/fate/matroska-flac-extradata-update |  4 ++--
>  3 files changed, 14 insertions(+), 18 deletions(-)
> 
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 0972bbfd5c..0f8efabab9 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -1567,12 +1567,12 @@ It influences which tracks players should play by default. The default mode
>  is @samp{infer}.
>  @table @samp
>  @item infer
> -In this mode, for each type of track (audio, video or subtitle), if there is
> -a track with disposition default of this type, then the first such track
> -(i.e. the one with the lowest index) will be marked as default; if no such
> -track exists, the first track of this type will be marked as default instead
> -(if existing). This ensures that the default flag is set in a sensible way even
> -if the input originated from containers that lack the concept of default tracks.
> +Every track with disposition default will have the FlagDefault set.
> +Additionally, for each type of track (audio, video or subtitle), if no track
> +with disposition default of this type exists, then the first track of this type
> +will be marked as default (if existing). This ensures that the default flag
> +is set in a sensible way even if the input originated from containers that
> +lack the concept of default tracks.
>  @item infer_no_subs
>  This mode is the same as infer except that if no subtitle track with
>  disposition default exists, no subtitle track will be marked as default.
> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
> index 899a3388cd..e2d9159e2c 100644
> --- a/libavformat/matroskaenc.c
> +++ b/libavformat/matroskaenc.c
> @@ -1395,7 +1395,8 @@ static int mkv_write_tracks(AVFormatContext *s)
>  {
>      MatroskaMuxContext *mkv = s->priv_data;
>      AVIOContext *pb = s->pb;
> -    int i, ret, video_default_idx, audio_default_idx, subtitle_default_idx;
> +    int video_default_idx = -1, audio_default_idx = -1, subtitle_default_idx = -1;
> +    int i, ret;
>  
>      if (mkv->nb_attachments == s->nb_streams)
>          return 0;
> @@ -1405,11 +1406,7 @@ static int mkv_write_tracks(AVFormatContext *s)
>          return ret;
>  
>      if (mkv->default_mode != DEFAULT_MODE_PASSTHROUGH) {
> -        int video_idx, audio_idx, subtitle_idx;
> -
> -        video_idx    = video_default_idx    =
> -        audio_idx    = audio_default_idx    =
> -        subtitle_idx = subtitle_default_idx = -1;
> +        int video_idx = -1, audio_idx = -1, subtitle_idx = -1;
>  
>          for (i = s->nb_streams - 1; i >= 0; i--) {
>              AVStream *st = s->streams[i];
> @@ -1435,8 +1432,7 @@ static int mkv_write_tracks(AVFormatContext *s)
>      }
>      for (i = 0; i < s->nb_streams; i++) {
>          AVStream *st = s->streams[i];
> -        int is_default = mkv->default_mode == DEFAULT_MODE_PASSTHROUGH ?
> -                             st->disposition & AV_DISPOSITION_DEFAULT  :
> +        int is_default = st->disposition & AV_DISPOSITION_DEFAULT ||
>                               i == video_default_idx || i == audio_default_idx ||
>                               i == subtitle_default_idx;
>          ret = mkv_write_track(s, mkv, st, &mkv->tracks[i],
> @@ -2823,8 +2819,8 @@ static const AVOption options[] = {
>      { "flipped_raw_rgb", "Raw RGB bitmaps in VFW mode are stored bottom-up", OFFSET(flipped_raw_rgb), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
>      { "write_crc32", "write a CRC32 element inside every Level 1 element", OFFSET(write_crc), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
>      { "default_mode", "Controls how a track's FlagDefault is inferred", OFFSET(default_mode), AV_OPT_TYPE_INT, { .i64 = DEFAULT_MODE_INFER }, DEFAULT_MODE_INFER, DEFAULT_MODE_PASSTHROUGH, FLAGS, "default_mode" },
> -    { "infer", "For each track type, mark the first track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" },
> -    { "infer_no_subs", "For each track type, mark the first track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" },
> +    { "infer", "For each track type, mark each track of disposition default as default; if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" },
> +    { "infer_no_subs", "For each track type, mark each track of disposition default as default; for audio and video: if none exists, mark the first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" },
>      { "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" },
>      { NULL },
>  };
> diff --git a/tests/ref/fate/matroska-flac-extradata-update b/tests/ref/fate/matroska-flac-extradata-update
> index fb17bfea0b..1a8add7736 100644
> --- a/tests/ref/fate/matroska-flac-extradata-update
> +++ b/tests/ref/fate/matroska-flac-extradata-update
> @@ -1,5 +1,5 @@
> -3c721898cf2cf3e2e6c43ad58952bd2d *tests/data/fate/matroska-flac-extradata-update.matroska
> -2032 tests/data/fate/matroska-flac-extradata-update.matroska
> +c2b76d47a9f0e9626a4999bd395cae08 *tests/data/fate/matroska-flac-extradata-update.matroska
> +2029 tests/data/fate/matroska-flac-extradata-update.matroska
>  #extradata 0:       34, 0x7acb09e7
>  #extradata 1:       34, 0x7acb09e7
>  #extradata 2:       34, 0x443402dd
> 
Will apply this patchset tonight unless there are objections.

- Andreas