Allows extraction (to side data) and removal of closed captions in
user data blocks.
---
doc/bitstream_filters.texi | 12 ++++++
libavcodec/Makefile | 2 +-
libavcodec/mpeg2_metadata_bsf.c | 81 ++++++++++++++++++++++++++++++++++++++++-
3 files changed, 93 insertions(+), 2 deletions(-)
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index 41424cf42f..f115f7b0c5 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -465,6 +465,18 @@ 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 captions in user data blocks.
+
+@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/Makefile b/libavcodec/Makefile
index cfde104055..e5430ab10b 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1057,7 +1057,7 @@ OBJS-$(CONFIG_MPEG4_UNPACK_BFRAMES_BSF) +=
mpeg4_unpack_bframes_bsf.o
OBJS-$(CONFIG_MOV2TEXTSUB_BSF) += movsub_bsf.o
OBJS-$(CONFIG_MP3_HEADER_DECOMPRESS_BSF) += mp3_header_decompress_bsf.o \
mpegaudiodata.o
-OBJS-$(CONFIG_MPEG2_METADATA_BSF) += mpeg2_metadata_bsf.o
+OBJS-$(CONFIG_MPEG2_METADATA_BSF) += mpeg2_metadata_bsf.o cbs_misc.o
OBJS-$(CONFIG_NOISE_BSF) += noise_bsf.o
OBJS-$(CONFIG_NULL_BSF) += null_bsf.o
OBJS-$(CONFIG_REMOVE_EXTRADATA_BSF) += remove_extradata_bsf.o
diff --git a/libavcodec/mpeg2_metadata_bsf.c b/libavcodec/mpeg2_metadata_bsf.c
index e787cb3782..49335d7fcb 100644
--- a/libavcodec/mpeg2_metadata_bsf.c
+++ b/libavcodec/mpeg2_metadata_bsf.c
@@ -22,9 +22,17 @@
#include "bsf.h"
#include "cbs.h"
+#include "cbs_misc.h"
#include "cbs_mpeg2.h"
#include "mpeg12.h"
+enum {
+ PASS,
+ INSERT,
+ REMOVE,
+ EXTRACT,
+};
+
typedef struct MPEG2MetadataContext {
const AVClass *class;
@@ -42,6 +50,8 @@ typedef struct MPEG2MetadataContext {
int transfer_characteristics;
int matrix_coefficients;
+ int a53_cc;
+
int mpeg1_warned;
} MPEG2MetadataContext;
@@ -184,7 +194,9 @@ 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 +214,51 @@ 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;
+ A53UserData a53_ud;
+
+ if (frag->units[i].type != MPEG2_START_USER_DATA)
+ continue;
+ ud = frag->units[i].content;
+
+ err = ff_cbs_read_a53_user_data(ctx->cbc, &a53_ud, ud->user_data,
+ ud->user_data_length);
+ if (err < 0) {
+ // Invalid or something completely different.
+ continue;
+ }
+ if (a53_ud.user_identifier != A53_USER_IDENTIFIER_ATSC ||
+ a53_ud.atsc.user_data_type_code !=
+ A53_USER_DATA_TYPE_CODE_CC_DATA) {
+ // Valid but something else (e.g. AFD).
+ 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 "
+ "A/53 CC user data.\n");
+ goto fail;
+ }
+ --i;
+ break;
+ } else if(ctx->a53_cc == EXTRACT) {
+ err = ff_cbs_write_a53_cc_side_data(ctx->cbc,
+ &a53_side_data,
+ &a53_side_data_size,
+ &a53_ud);
+ if (err < 0) {
+ av_log(bsf, AV_LOG_ERROR, "Failed to write "
+ "A/53 user data for packet side data.\n");
+ goto fail;
+ }
+ }
+ }
+ }
+
err = ff_cbs_write_packet(ctx->cbc, out, frag);
if (err < 0) {
av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
@@ -212,9 +269,21 @@ static int mpeg2_metadata_filter(AVBSFContext *bsf,
AVPacket *out)
if (err < 0)
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);
if (err < 0)
av_packet_unref(out);
@@ -289,6 +358,16 @@ static const AVOption mpeg2_metadata_options[] = {
OFFSET(matrix_coefficients), AV_OPT_TYPE_INT,
{ .i64 = -1 }, -1, 255, FLAGS },
+ { "a53_cc", "A/53 Closed Captions in user data",
+ OFFSET(a53_cc), AV_OPT_TYPE_INT,
+ { .i64 = PASS }, PASS, EXTRACT, FLAGS, "a53_cc" },
+ { "pass", NULL, 0, AV_OPT_TYPE_CONST,
+ { .i64 = PASS }, .flags = FLAGS, .unit = "a53_cc" },
+ { "remove", NULL, 0, AV_OPT_TYPE_CONST,
+ { .i64 = REMOVE }, .flags = FLAGS, .unit = "a53_cc" },
+ { "extract", NULL, 0, AV_OPT_TYPE_CONST,
+ { .i64 = EXTRACT }, .flags = FLAGS, .unit = "a53_cc" },
+
{ NULL }
};
--
2.16.1
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