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

[Mathieu Duponchelle]

---
 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 }, \
 
 extern const AVOption ff_mpv_generic_options[];
 
-- 
2.20.1