[FFmpeg-devel] [PATCH 1/2] avformat/matroskaenc: fix Tags master on seekable output if there are tags after the last stream duration

[James Almer]

On 10/7/2016 3:05 AM, James Almer wrote:
> The dynamic AVIOContext would get closed pointing to the wrong position
> in the buffer.
> This is a regression since 650e17d88b63b5aca6e0a43483e89e64b0f7d2dd.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> Example:
> ./ffmpeg -i fate-samples/vorbis/vorbis_chapter_extension_demo.ogg -c:a copy -metadata:c key=value out.mka
> 
> The output is corrupt before this patch.
> 
> The refactoring isn't necessary per se, but it comes in handy for the next patch,
> where attachments will not be treated as tracks anymore when writting tags.
> 
>  libavformat/matroskaenc.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
> index 0878cb5..286b8b4 100644
> --- a/libavformat/matroskaenc.c
> +++ b/libavformat/matroskaenc.c
> @@ -2264,17 +2264,19 @@ static int mkv_write_trailer(AVFormatContext *s)
>          end_ebml_master_crc32(pb, &mkv->info_bc, mkv, mkv->info);
>  
>          // update stream durations
> -        if (mkv->stream_durations) {
> +        if (!mkv->is_live && mkv->stream_durations) {
>              int i;
> +            int64_t curr = avio_tell(mkv->tags_bc);
>              for (i = 0; i < s->nb_streams; ++i) {
>                  AVStream *st = s->streams[i];
> -                double duration_sec = mkv->stream_durations[i] * av_q2d(st->time_base);
> -                char duration_string[20] = "";
>  
> -                av_log(s, AV_LOG_DEBUG, "stream %d end duration = %" PRIu64 "\n", i,
> -                       mkv->stream_durations[i]);
> +                if (mkv->stream_duration_offsets[i] > 0) {
> +                    double duration_sec = mkv->stream_durations[i] * av_q2d(st->time_base);
> +                    char duration_string[20] = "";
> +
> +                    av_log(s, AV_LOG_DEBUG, "stream %d end duration = %" PRIu64 "\n", i,
> +                           mkv->stream_durations[i]);
>  
> -                if (!mkv->is_live && mkv->stream_duration_offsets[i] > 0) {
>                      avio_seek(mkv->tags_bc, mkv->stream_duration_offsets[i], SEEK_SET);
>  
>                      snprintf(duration_string, 20, "%02d:%02d:%012.9f",
> @@ -2284,6 +2286,7 @@ static int mkv_write_trailer(AVFormatContext *s)
>                      put_ebml_binary(mkv->tags_bc, MATROSKA_ID_TAGSTRING, duration_string, 20);
>                  }
>              }
> +            avio_seek(mkv->tags_bc, curr, SEEK_SET);
>          }
>          if (mkv->tags.pos && !mkv->is_live) {
>              avio_seek(pb, mkv->tags.pos, SEEK_SET);


Ping. It's a recent regression on a muxer, so I'd like to solve it asap.
I'll push it later today if nobody comments.