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mpegvideoparse: extract CEA-708 closed captions

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This commit is contained in:
Tim-Philipp Müller 2018-11-28 17:05:33 +00:00
parent fed05fcdf2
commit 1b0e150d88
2 changed files with 85 additions and 0 deletions
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80
gst/videoparsers/gstmpegvideoparse.c
View file

@ -461,6 +461,56 @@ parse_packet_extension (GstMpegvParse * mpvparse, GstMapInfo * info, guint off)
}
}
/* A53-4 Table 6.7 */
#define A53_USER_DATA_ID_GA94 0x47413934
#define A53_USER_DATA_ID_DTG1 0x44544731
/* A53-4 Table 6.9 */
#define A53_USER_DATA_TYPE_CODE_MPEG_CC_DATA 0x03
#define A53_USER_DATA_TYPE_CODE_BAR_DATA 0x06
/* CEA-708 Table 2 */
#define CEA_708_PROCESS_CC_DATA_FLAG 0x40
static void
parse_user_data_packet (GstMpegvParse * mpvparse, const guint8 * data,
guint size)
{
if (size < 2) {
GST_DEBUG_OBJECT (mpvparse, "user data packet too short, ignoring");
return;
}
/* A53 part 4 closed captions */
if (size > 6 && GST_READ_UINT32_BE (data) == A53_USER_DATA_ID_GA94
&& data[4] == A53_USER_DATA_TYPE_CODE_MPEG_CC_DATA
&& (data[5] & CEA_708_PROCESS_CC_DATA_FLAG) != 0 && data[6] == 0xff) {
guint8 cc_count = data[5] & 0x1f;
guint cc_size = cc_count * 3;
data += 7;
size -= 7;
if (cc_size == 0 || cc_size > size) {
GST_DEBUG_OBJECT (mpvparse, "ignoring closed captions, not enough data");
return;
}
/* Shouldn't really happen so let's not go out of our way to handle it */
if (mpvparse->closedcaptions_size > 0)
GST_WARNING_OBJECT (mpvparse, "unused pending closed captions!");
g_assert (cc_size <= sizeof (mpvparse->closedcaptions));
memcpy (mpvparse->closedcaptions, data, cc_size);
mpvparse->closedcaptions_size = cc_size;
mpvparse->closedcaptions_type = GST_VIDEO_CAPTION_TYPE_CEA708_RAW;
GST_DEBUG_OBJECT (mpvparse, "CEA-708 closed captions, %u bytes", cc_size);
return;
}
GST_MEMDUMP_OBJECT (mpvparse, "unhandled user data packet", data, size);
}
/* caller guarantees at least start code in @buf at @off ( - 4)*/
/* for off == 4 initial code; returns TRUE if code starts a frame
* otherwise returns TRUE if code terminates preceding frame */
@ -515,6 +565,18 @@ gst_mpegv_parse_process_sc (GstMpegvParse * mpvparse,
}
checkconfig = FALSE;
break;
case GST_MPEG_VIDEO_PACKET_USER_DATA:
GST_LOG_OBJECT (mpvparse, "USER_DATA packet of %d bytes", packet->size);
if (packet->size < 0) {
GST_LOG_OBJECT (mpvparse, "no size yet, need more data");
*need_more = TRUE;
return FALSE;
}
parse_user_data_packet (mpvparse, info->data + off, packet->size);
checkconfig = FALSE;
break;
default:
if (GST_MPEG_VIDEO_PACKET_IS_SLICE (packet->type)) {
mpvparse->slice_count++;
@ -1002,6 +1064,24 @@ gst_mpegv_parse_pre_push_frame (GstBaseParse * parse, GstBaseParseFrame * frame)
meta->num_slices = mpvparse->slice_count;
meta->slice_offset = mpvparse->slice_offset;
}
if (mpvparse->closedcaptions_size > 0) {
GstBuffer *buf;
if (frame->out_buffer) {
buf = frame->out_buffer = gst_buffer_make_writable (frame->out_buffer);
} else {
buf = frame->buffer = gst_buffer_make_writable (frame->buffer);
}
gst_buffer_add_video_caption_meta (buf,
mpvparse->closedcaptions_type, mpvparse->closedcaptions,
mpvparse->closedcaptions_size);
mpvparse->closedcaptions_type = GST_VIDEO_CAPTION_TYPE_UNKNOWN;
mpvparse->closedcaptions_size = 0;
}
return GST_FLOW_OK;
}

5
gst/videoparsers/gstmpegvideoparse.h
View file

@ -87,6 +87,11 @@ struct _GstMpegvParse {
gboolean picext_updated;
gboolean quantmatrext_updated;
/* pending closed captions */
guint8 closedcaptions[96];
guint closedcaptions_size;
GstVideoCaptionType closedcaptions_type;
/* properties */
gboolean drop;
gboolean gop_split;