From: Aman Gupta <a...@tmm1.net>
---
doc/bitstream_filters.texi | 12 +++++++
libavcodec/mpeg2_metadata_bsf.c | 79 ++++++++++++++++++++++++++++++++++++++++-
2 files changed, 90 insertions(+), 1 deletion(-)
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index b7ea549322..c0b48e62dc 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -362,6 +362,18 @@ table 6-6).
Set the colour description in the stream (see H.262 section 6.3.6
and tables 6-7, 6-8 and 6-9).
+@item a53_cc
+Modify A/53 closed caption data in user data messages.
+
+@table @samp
+@item remove
+Remove all closed caption data from the stream.
+
+@item extract
+Extract closed captions from the stream so that they are available as
+as packet side data.
+@end table
+
@end table
@section mpeg4_unpack_bframes
diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
index 3bb6c1d549..0728ca4e09 100644
--- a/libavcodec/mpeg2_metadata_bsf.c
+++ b/libavcodec/mpeg2_metadata_bsf.c
@@ -25,6 +25,12 @@
#include "cbs_mpeg2.h"
#include "mpeg12.h"
+enum {
+ PASS,
+ REMOVE,
+ EXTRACT,
+};
+
typedef struct MPEG2MetadataContext {
const AVClass *class;
@@ -43,6 +49,7 @@ typedef struct MPEG2MetadataContext {
int matrix_coefficients;
int mpeg1_warned;
+ int a53_cc;
} MPEG2MetadataContext;
@@ -184,7 +191,9 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
AVPacket *out)
MPEG2MetadataContext *ctx = bsf->priv_data;
AVPacket *in = NULL;
CodedBitstreamFragment *frag = &ctx->fragment;
- int err;
+ int err, i;
+ uint8_t *a53_side_data = NULL;
+ size_t a53_side_data_size = 0;
err = ff_bsf_get_packet(bsf, &in);
if (err < 0)
@@ -202,6 +211,55 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
AVPacket *out)
goto fail;
}
+ if (ctx->a53_cc == REMOVE || ctx->a53_cc == EXTRACT) {
+ for (i = 0; i < frag->nb_units; i++) {
+ MPEG2RawUserData *ud = NULL;
+ uint32_t tag;
+ uint8_t type_code, count;
+
+ if (frag->units[i].type != MPEG2_START_USER_DATA)
+ continue;
+ ud = frag->units[i].content;
+ if (ud->user_data_length < 6)
+ continue;
+ tag = AV_RB32(ud->user_data);
+ type_code = ud->user_data[4];
+ if (tag != MKBETAG('G', 'A', '9', '4') || type_code != 3)
+ continue;
+
+ if (ctx->a53_cc == REMOVE) {
+ err = ff_cbs_delete_unit(ctx->cbc, frag, i);
+ if (err < 0) {
+ av_log(bsf, AV_LOG_ERROR, "Failed to delete "
+ "A53 CC USER_DATA message.\n");
+ goto fail;
+ }
+ av_log(bsf, AV_LOG_WARNING, "A53 CC remove!.\n");
+
+ --i;
+ break;
+ }
+
+ // Extract.
+ count = ud->user_data[5] & 0x1f;
+ if (3 * count + 8 > ud->user_data_length) {
+ av_log(bsf, AV_LOG_ERROR, "Invalid A/53 closed caption "
+ "data: count %d overflows length %zu.\n",
+ count, ud->user_data_length);
+ continue;
+ }
+ av_log(bsf, AV_LOG_WARNING, "A53 CC extract: %zu bytes.\n",
ud->user_data_length);
+
+ err = av_reallocp(&a53_side_data,
+ a53_side_data_size + 3 * count);
+ if (err)
+ goto fail;
+ memcpy(a53_side_data + a53_side_data_size,
+ ud->user_data + 9, 3 * count);
+ a53_side_data_size += 3 * count;
+ }
+ }
+
err = ff_cbs_write_packet(ctx->cbc, out, frag);
if (err < 0) {
av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
@@ -214,9 +272,21 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
AVPacket *out)
goto fail;
}
+ if (a53_side_data) {
+ err = av_packet_add_side_data(out, AV_PKT_DATA_A53_CC,
+ a53_side_data, a53_side_data_size);
+ if (err) {
+ av_log(bsf, AV_LOG_ERROR, "Failed to attach extracted A/53 "
+ "side data to packet.\n");
+ goto fail;
+ }
+ a53_side_data = NULL;
+ }
+
err = 0;
fail:
ff_cbs_fragment_uninit(ctx->cbc, frag);
+ av_freep(&a53_side_data);
av_packet_free(&in);
@@ -288,6 +358,13 @@ static const AVOption mpeg2_metadata_options[] = {
OFFSET(matrix_coefficients), AV_OPT_TYPE_INT,
{ .i64 = -1 }, -1, 255 },
+ { "a53_cc", "A/53 Closed Captions in SEI NAL units",
+ OFFSET(a53_cc), AV_OPT_TYPE_INT,
+ { .i64 = PASS }, PASS, EXTRACT, 0, "a53_cc" },
+ { "pass", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = PASS }, .unit =
"a53_cc" },
+ { "remove", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE }, .unit =
"a53_cc" },
+ { "extract", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = EXTRACT }, .unit =
"a53_cc" },
+
{ NULL }
};
--
2.14.2
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