If AV_FRAME_DATA_A53_CC "user data" is available, encode it into the mpeg
picture header.
This follows the spec in section 6.2.3 of
http://atsc.org/wp-content/uploads/2015/03/a_53-Part-4-2009.pdf
I am working on gstreamer side, to inject the information into the ffmpeg
side data, and have it generally working.
It would also be trivial to add "AV_FRAME_DATA_A53_BAR", but I don't
currently have a way to test that.
John
From 6c835804b4eaacc27272667d197b63eb76f8d41c Mon Sep 17 00:00:00 2001
From: John Poet <jpp...@digital-nirvana.com>
Date: Tue, 21 Mar 2017 10:02:10 -0600
Subject: [PATCH] Add A53 closed captions to mpeg picture header.
If AV_FRAME_DATA_A53_CC "user data" is available, encode it into the mpeg
picture header.
---
libavcodec/mpeg12enc.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/libavcodec/mpeg12enc.c b/libavcodec/mpeg12enc.c
index f45598a..b33e8be 100644
--- a/libavcodec/mpeg12enc.c
+++ b/libavcodec/mpeg12enc.c
@@ -543,6 +543,23 @@ void ff_mpeg1_encode_picture_header(MpegEncContext *s, int picture_number)
}
}
+ side_data = av_frame_get_side_data(s->current_picture_ptr->f,
+ AV_FRAME_DATA_A53_CC);
+ if (side_data) {
+ avpriv_align_put_bits(&s->pb);
+ put_header(s, USER_START_CODE);
+ put_bits(&s->pb, 8, 'G'); // ATSC_user_data
+ put_bits(&s->pb, 8, 'A');
+ put_bits(&s->pb, 8, '9');
+ put_bits(&s->pb, 8, '4');
+
+ put_bits(&s->pb, 8, 0x03); // MPEG_cc_data
+
+ for(int idx = 0; idx < side_data->size; ++idx) {
+ put_bits(&s->pb, 8, side_data->data[idx]);
+ }
+ }
+
s->mb_y = 0;
ff_mpeg1_encode_slice_header(s);
}
--
2.1.4
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