[FFmpeg-devel] [PATCH v6] mpeg12enc: Use Closed Captions if available

[Aman Gupta]

On Fri, Feb 8, 2019 at 7:26 AM Mathieu Duponchelle <mathieu at centricular.com>
wrote:

> ---
>  doc/encoders.texi      |  3 +++
>  libavcodec/mpeg12enc.c | 32 ++++++++++++++++++++++++++++++++
>  libavcodec/mpegvideo.h |  2 ++
>  3 files changed, 37 insertions(+)
>
> diff --git a/doc/encoders.texi b/doc/encoders.texi
> index e86ae69cc5..a283b9fddf 100644
> --- a/doc/encoders.texi
> +++ b/doc/encoders.texi
> @@ -2574,6 +2574,9 @@ Specifies the video_format written into the sequence
> display extension
>  indicating the source of the video pictures. The default is
> @samp{unspecified},
>  can be @samp{component}, @samp{pal}, @samp{ntsc}, @samp{secam} or
> @samp{mac}.
>  For maximum compatibility, use @samp{component}.
> + at item a53cc @var{boolean}
> +Import closed captions (which must be ATSC compatible format) into output.
> +Default is 1 (on).
>  @end table
>
>  @section png
> diff --git a/libavcodec/mpeg12enc.c b/libavcodec/mpeg12enc.c
> index d0b458e34b..2bc5289d63 100644
> --- a/libavcodec/mpeg12enc.c
> +++ b/libavcodec/mpeg12enc.c
> @@ -61,6 +61,8 @@ static uint32_t mpeg1_chr_dc_uni[512];
>  static uint8_t mpeg1_index_run[2][64];
>  static int8_t  mpeg1_max_level[2][64];
>
> +#define A53_MAX_CC_COUNT 0x1f
> +
>  static av_cold void init_uni_ac_vlc(RLTable *rl, uint8_t *uni_ac_vlc_len)
>  {
>      int i;
> @@ -544,6 +546,36 @@ void ff_mpeg1_encode_picture_header(MpegEncContext
> *s, int picture_number)
>          }
>      }
>
> +    if (s->codec_id == AV_CODEC_ID_MPEG2VIDEO && s->a53_cc) {
> +        side_data = av_frame_get_side_data(s->current_picture_ptr->f,
> +            AV_FRAME_DATA_A53_CC);
> +        if (side_data) {
> +            if (side_data->size <= A53_MAX_CC_COUNT * 3 &&
> side_data->size % 3 == 0) {
> +                int i = 0;
> +
> +                put_header (s, USER_START_CODE);
> +
> +                put_bits(&s->pb, 8, 'G');                   //
> user_identifier
> +                put_bits(&s->pb, 8, 'A');
> +                put_bits(&s->pb, 8, '9');
> +                put_bits(&s->pb, 8, '4');
> +                put_bits(&s->pb, 8, 3);                     //
> user_data_type_code
> +                put_bits(&s->pb, 8,
> +                    (side_data->size / 3 & A53_MAX_CC_COUNT) | 0x40); //
> flags, cc_count
> +                put_bits(&s->pb, 8, 0xff);                  // em_data
> +
> +                for (i = 0; i < side_data->size; i++)
> +                    put_bits(&s->pb, 8, side_data->data[i]);
> +
> +                put_bits(&s->pb, 8, 0xff);                  // marker_bits
> +            } else {
> +                av_log(s->avctx, AV_LOG_WARNING,
> +                    "Warning Closed Caption size (%d) can not exceed 93
> bytes "
> +                    "and must be a multiple of 3\n", side_data->size);
> +            }
> +        }
> +    }
> +
>      s->mb_y = 0;
>      ff_mpeg1_encode_slice_header(s);
>  }
> diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
> index bbc6b5646a..3e52f98390 100644
> --- a/libavcodec/mpegvideo.h
> +++ b/libavcodec/mpegvideo.h
> @@ -455,6 +455,7 @@ typedef struct MpegEncContext {
>      /* MPEG-2-specific - I wished not to have to support this mess. */
>      int progressive_sequence;
>      int mpeg_f_code[2][2];
> +    int a53_cc;
>
>      // picture structure defines are loaded from mpegutils.h
>      int picture_structure;
> @@ -663,6 +664,7 @@ FF_MPV_OPT_CMP_FUNC, \
>  {"ps", "RTP payload size in bytes",
>  FF_MPV_OFFSET(rtp_payload_size), AV_OPT_TYPE_INT, {.i64 = 0 }, INT_MIN,
> INT_MAX, FF_MPV_OPT_FLAGS }, \
>  {"mepc", "Motion estimation bitrate penalty compensation (1.0 = 256)",
> FF_MPV_OFFSET(me_penalty_compensation), AV_OPT_TYPE_INT, {.i64 = 256 },
> INT_MIN, INT_MAX, FF_MPV_OPT_FLAGS }, \
>  {"mepre", "pre motion estimation", FF_MPV_OFFSET(me_pre),
> AV_OPT_TYPE_INT, {.i64 = 0 }, INT_MIN, INT_MAX, FF_MPV_OPT_FLAGS }, \
> +{ "a53cc", "Use A53 Closed Captions (if available)",
> FF_MPV_OFFSET(a53_cc), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, FF_MPV_OPT_FLAGS
> }, \
>

Could you remove the space after the { to match the other definitions above.


>
>  extern const AVOption ff_mpv_generic_options[];
>
> --
> 2.20.1
>
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