[FFmpeg-devel] [PATCH 2/4] avformat/mxfenc: use track count to generate component instance uuid

[Tomas Härdin]

On Sun, 2017-11-26 at 21:42 -0800, Mark Reid wrote:
> ---
>  libavformat/mxf.h               |  1 -
>  libavformat/mxfenc.c            | 45 +++++++++++++++++++++++++----
> ------------
>  tests/ref/fate/copy-trac4914    |  2 +-
>  tests/ref/fate/time_base        |  2 +-
>  tests/ref/lavf/mxf              |  6 +++---
>  tests/ref/lavf/mxf_d10          |  2 +-
>  tests/ref/lavf/mxf_dv25         |  2 +-
>  tests/ref/lavf/mxf_dvcpro50     |  2 +-
>  tests/ref/lavf/mxf_opatom       |  2 +-
>  tests/ref/lavf/mxf_opatom_audio |  2 +-
>  10 files changed, 38 insertions(+), 28 deletions(-)
> [...]
> @@ -846,6 +847,10 @@ static void
> mxf_write_track(AVFormatContext *s, AVStream *st, MXFPackage *packag
>      MXFContext *mxf = s->priv_data;
>      AVIOContext *pb = s->pb;
>      MXFStreamContext *sc = st->priv_data;
> +    int instance = package->uuid_offset;
> +
> +    if (st != mxf->timecode_track)
> +        instance += st->index + 1;
>  
>      mxf_write_metadata_key(pb, 0x013b00);
>      PRINT_KEY(s, "track key", pb->buf_ptr - 16);
> 
>  static int mxf_write_essence_container_data(AVFormatContext *s)
> @@ -1443,11 +1451,12 @@ static int
> mxf_write_header_metadata_sets(AVFormatContext *s)
>      AVDictionaryEntry *entry = NULL;
>      AVStream *st = NULL;
>      int i;
> -
> +    int track_count = 0;
>      MXFPackage packages[2] = {};
>      int package_count = 2;
>      packages[0].type = MaterialPackage;
>      packages[1].type = SourcePackage;
> +    packages[1].instance = 1;
>  
>      if (entry = av_dict_get(s->metadata, "material_package_name",
> NULL, 0))
>         packages[0].name = entry->value;
> @@ -1468,8 +1477,10 @@ static int
> mxf_write_header_metadata_sets(AVFormatContext *s)
>      mxf_write_preface(s);
>      mxf_write_identification(s);
>      mxf_write_content_storage(s, packages, package_count);
> -    for (i = 0; i < package_count; i++)
> -        mxf_write_package(s, &packages[i]);
> +    for (i = 0; i < package_count; i++) {
> +        packages[i].uuid_offset = track_count;
> +        track_count += mxf_write_package(s, &packages[i]);
> +    }

I see st->index + 1 when deriving instance from uuid_offset, are you
sure there isn't a potential off-by-one error here? An MP track and SP
track getting the same UUID or something. I guess type is enough to
differentiate, but then why does instance need uuid_offset?

/Tomas
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