[FFmpeg-devel] [PATCH] matroska: Set CodecDelay and SeekPreroll in the AVStream

[Vignesh Venkatasubramanian]

On Mon, Sep 23, 2013 at 4:02 PM, Vignesh Venkatasubramanian
<vigneshv at google.com> wrote:
> This patch exports the values of Codec Delay and Seek Preroll
> container elements as in the AVStream structure. The seek_preroll
> field has been added to the AVStream struct and the minor version
> of libavformat has been bumped.
>
> Signed-off-by: Vignesh Venkatasubramanian <vigneshv at google.com>
> ---
>  libavformat/avformat.h    | 16 ++++++++++++++++
>  libavformat/matroskadec.c | 14 ++++++++++++++
>  libavformat/version.h     |  2 +-
>  3 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/libavformat/avformat.h b/libavformat/avformat.h
> index b18eb3f..6671a83 100644
> --- a/libavformat/avformat.h
> +++ b/libavformat/avformat.h
> @@ -856,6 +856,9 @@ typedef struct AVStream {
>
>      /**
>       * Number of samples to skip at the start of the frame decoded from the next packet.
> +     *
> +     * Code outside avformat should access this field using:
> +     * av_stream_get_skip_samples/set_skip_samples(stream)
>       */
>      int skip_samples;
>
> @@ -888,10 +891,23 @@ typedef struct AVStream {
>       */
>      int pts_wrap_behavior;
>
> +    /**
> +     * Number of samples to skip after a discontinuity. For example, when a seek
> +     * happens.
> +     *
> +     * Code outside avformat should access this field using:
> +     * av_stream_get/set_seek_preroll(stream)
> +     */
> +    int seek_preroll;
> +
>  } AVStream;
>
>  AVRational av_stream_get_r_frame_rate(const AVStream *s);
>  void       av_stream_set_r_frame_rate(AVStream *s, AVRational r);
> +int  av_stream_get_skip_samples(const AVStream *s);
> +void av_stream_set_skip_samples(AVStream *s, int skip_samples);
> +int  av_stream_get_seek_preroll(const AVStream *s);
> +void av_stream_set_seek_preroll(AVStream *s, int seek_preroll);
>
>  #define AV_PROGRAM_RUNNING 1
>
> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
> index a1b7f56..ecbc723 100644
> --- a/libavformat/matroskadec.c
> +++ b/libavformat/matroskadec.c
> @@ -163,6 +163,8 @@ typedef struct {
>      uint64_t default_duration;
>      uint64_t flag_default;
>      uint64_t flag_forced;
> +    uint64_t codec_delay;
> +    uint64_t seek_preroll;
>      MatroskaTrackVideo video;
>      MatroskaTrackAudio audio;
>      MatroskaTrackOperation operation;
> @@ -410,6 +412,8 @@ static EbmlSyntax matroska_track[] = {
>      { MATROSKA_ID_TRACKOPERATION,       EBML_NEST, 0, offsetof(MatroskaTrack,operation), {.n=matroska_track_operation} },
>      { MATROSKA_ID_TRACKCONTENTENCODINGS,EBML_NEST, 0, 0, {.n=matroska_track_encodings} },
>      { MATROSKA_ID_TRACKMAXBLKADDID,     EBML_UINT, 0, offsetof(MatroskaTrack,max_block_additional_id) },
> +    { MATROSKA_ID_CODECDELAY,           EBML_UINT, 0, offsetof(MatroskaTrack,codec_delay) },
> +    { MATROSKA_ID_SEEKPREROLL,          EBML_UINT, 0, offsetof(MatroskaTrack,seek_preroll) },
>      { MATROSKA_ID_TRACKFLAGENABLED,     EBML_NONE },
>      { MATROSKA_ID_TRACKFLAGLACING,      EBML_NONE },
>      { MATROSKA_ID_CODECNAME,            EBML_NONE },
> @@ -1874,6 +1878,16 @@ static int matroska_read_header(AVFormatContext *s)
>              st->codec->bits_per_coded_sample = track->audio.bitdepth;
>              if (st->codec->codec_id != AV_CODEC_ID_AAC)
>              st->need_parsing = AVSTREAM_PARSE_HEADERS;
> +            if (track->codec_delay > 0) {
> +                st->skip_samples = av_rescale_q(track->codec_delay,
> +                                                (AVRational){1, 1000000000},
> +                                                (AVRational){1, st->codec->sample_rate});
> +            }
> +            if (track->seek_preroll > 0) {
> +                st->seek_preroll = av_rescale_q(track->seek_preroll,
> +                                                (AVRational){1, 1000000000},
> +                                                (AVRational){1, st->codec->sample_rate});
> +            }
>          } else if (codec_id == AV_CODEC_ID_WEBVTT) {
>              st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
>
> diff --git a/libavformat/version.h b/libavformat/version.h
> index c224232..ff38e96 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -30,7 +30,7 @@
>  #include "libavutil/avutil.h"
>
>  #define LIBAVFORMAT_VERSION_MAJOR 55
> -#define LIBAVFORMAT_VERSION_MINOR 18
> +#define LIBAVFORMAT_VERSION_MINOR 19
>  #define LIBAVFORMAT_VERSION_MICRO 102

I am unsure if i should reset the micro version while bumping the
minor version. Looking at
older patches suggests that i shouldn't. Please let me know if i'm
wrong. Thanks.

>
>  #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> --
> 1.8.4
>