On Mon, Mar 12, 2018 at 12:24 AM, Aman Gupta <ffm...@tmm1.net> wrote:
> 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 changed these to TRACE locally, but I'll mimic whatever happens in the
h264_metadata version of the patch.
> +
> + --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);
>
This should be ud->user_data + 7. Fixed locally.
> + 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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