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

[Vignesh Venkatasubramanian]

On Fri, Aug 16, 2013 at 10:36 AM, Paul B Mahol <onemda at gmail.com> wrote:
> 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.

Not sure what you mean. S comes in between C and T. Could you please explain?

>
>> 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.

Sorry, some debug play around that snuck in by mistake. Will fix.

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