[FFmpeg-devel] [PATCH] lavf/matroska: Adding the new SeekPreRoll element

[Paul B Mahol]

On 8/16/13, Vignesh Venkatasubramanian <vigneshv at google.com> wrote:
> In order to encapsuate Opus in Matroska, there is a new element
> that has been added to the Matroska Spec, SeekPreRoll. It has the
> duration in nanoseconds that has to be decoded before every seek.
> Spec: http://matroska.org/technical/specs/index.html#SeekPreRoll
> Proposal for encapsulateing Opus in Matroska:
> http://wiki.xiph.org/MatroskaOpus
>
> Signed-off-by: Vignesh Venkatasubramanian <vigneshv at google.com>
> ---
>  libavformat/matroska.h    | 1 +
>  libavformat/matroskaenc.c | 8 ++++++++
>  2 files changed, 9 insertions(+)
>
> diff --git a/libavformat/matroska.h b/libavformat/matroska.h
> index 2eb2fe6..9c8071a 100644
> --- a/libavformat/matroska.h
> +++ b/libavformat/matroska.h
> @@ -91,6 +91,7 @@
>  #define MATROSKA_ID_CODECINFOURL 0x3B4040
>  #define MATROSKA_ID_CODECDOWNLOADURL 0x26B240
>  #define MATROSKA_ID_CODECDECODEALL 0xAA
> +#define MATROSKA_ID_SEEKPREROLL 0x56BB
>  #define MATROSKA_ID_TRACKNAME  0x536E
>  #define MATROSKA_ID_TRACKLANGUAGE 0x22B59C
>  #define MATROSKA_ID_TRACKFLAGENABLED 0xB9

Keep alphabetical order.

> diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
> index c201d5e..56109f9 100644
> --- a/libavformat/matroskaenc.c
> +++ b/libavformat/matroskaenc.c
> @@ -121,6 +121,9 @@ typedef struct MatroskaMuxContext {
>  /** per-cuepoint - 2 1-byte EBML IDs, 2 1-byte EBML sizes, 8-byte uint max
> */
>  #define MAX_CUEPOINT_SIZE(num_tracks) 12 + MAX_CUETRACKPOS_SIZE*num_tracks
>
> +/** Seek preroll value for opus */
> +#define OPUS_SEEK_PREROLL 80000000
> +
>
>  static int ebml_id_size(unsigned int id)
>  {
> @@ -642,6 +645,10 @@ static int mkv_write_tracks(AVFormatContext *s)
>              }
>          }
>
> +        if (codec->codec_id == AV_CODEC_ID_OPUS) {
> +            put_ebml_uint(pb, MATROSKA_ID_SEEKPREROLL, OPUS_SEEK_PREROLL);
> +        }
> +
>          if (mkv->mode == MODE_WEBM && !(codec->codec_id == AV_CODEC_ID_VP8
> ||
>                                          codec->codec_id == AV_CODEC_ID_VP9
> ||
>                                        ((codec->codec_id ==
> AV_CODEC_ID_OPUS)&&(codec->strict_std_compliance <=
> FF_COMPLIANCE_EXPERIMENTAL)) ||
> @@ -1721,6 +1728,7 @@ AVOutputFormat ff_matroska_audio_muxer = {
>      .priv_data_size    = sizeof(MatroskaMuxContext),
>      .audio_codec       = CONFIG_LIBVORBIS_ENCODER ?
>                           AV_CODEC_ID_VORBIS : AV_CODEC_ID_AC3,
> +                         AV_CODEC_ID_OPUS,

Unrelated and wrong.

>      .video_codec       = AV_CODEC_ID_NONE,
>      .write_header      = mkv_write_header,
>      .write_packet      = mkv_write_packet,
> --
> 1.8.3
>
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