[FFmpeg-devel] [PATCH 4/8] h264_metadata: Add support for A/53 closed captions

Hendrik Leppkes h.leppkes at gmail.com
Mon Mar 12 11:54:24 EET 2018


On Sun, Mar 11, 2018 at 7:30 PM, Mark Thompson <sw at jkqxz.net> wrote:
> ---
>  libavcodec/h264_metadata_bsf.c | 121 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 121 insertions(+)
>
> diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
> index 36047887ca..d340c55990 100644
> --- a/libavcodec/h264_metadata_bsf.c
> +++ b/libavcodec/h264_metadata_bsf.c
> @@ -77,6 +77,8 @@ typedef struct H264MetadataContext {
>      int display_orientation;
>      double rotate;
>      int flip;
> +
> +    int a53_cc;
>  } H264MetadataContext;
>
>
> @@ -225,6 +227,8 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *out)
>      int err, i, j, has_sps;
>      uint8_t *displaymatrix_side_data = NULL;
>      size_t displaymatrix_side_data_size = 0;
> +    uint8_t *a53_side_data = NULL;
> +    size_t a53_side_data_size = 0;
>
>      err = ff_bsf_get_packet(bsf, &in);
>      if (err < 0)
> @@ -514,6 +518,104 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *out)
>          }
>      }
>
> +    if (ctx->a53_cc == INSERT) {
> +        uint8_t *data;
> +        int size;
> +
> +        data = av_packet_get_side_data(in, AV_PKT_DATA_A53_CC, &size);
> +        if (data) {
> +            H264RawSEIPayload payload = {
> +                .payload_type = H264_SEI_TYPE_USER_DATA_REGISTERED,
> +            };
> +            H264RawSEIUserDataRegistered *udr =
> +                &payload.payload.user_data_registered;
> +
> +            av_log(bsf, AV_LOG_WARNING, "A53 CC insert: %d bytes.\n", size);
> +
> +            udr->data_length = size + 10;
> +            udr->data_ref    = av_buffer_alloc(udr->data_length);
> +            if (!udr->data_ref) {
> +                err = AVERROR(ENOMEM);
> +                goto fail;
> +            }
> +            udr->data = udr->data_ref->data;
> +
> +            udr->itu_t_t35_country_code = 181;
> +            udr->data[0] = 0;
> +            udr->data[1] = 49;
> +            AV_WB32(udr->data + 2, MKBETAG('G', 'A', '9', '4'));
> +            udr->data[6] = 3;
> +            udr->data[7] = ((size / 3) & 0x1f) | 0x40;
> +            udr->data[8] = 0;
> +            memcpy(udr->data + 9, data, size);
> +            udr->data[size + 9] = 0xff;
> +
> +            err = ff_cbs_h264_add_sei_message(ctx->cbc, au, &payload);
> +            if (err < 0) {
> +                av_log(bsf, AV_LOG_ERROR, "Failed to add user data SEI "
> +                       "message to access unit.\n");
> +                av_buffer_unref(&udr->data_ref);
> +                goto fail;
> +            }
> +        }
> +
> +    } else if (ctx->a53_cc == REMOVE || ctx->a53_cc == EXTRACT) {
> +        for (i = 0; i < au->nb_units; i++) {
> +            H264RawSEI *sei;
> +            if (au->units[i].type != H264_NAL_SEI)
> +                continue;
> +            sei = au->units[i].content;
> +
> +            for (j = 0; j < sei->payload_count; j++) {
> +                H264RawSEIUserDataRegistered *udr;
> +                uint32_t tag;
> +                uint8_t type_code, count;
> +
> +                if (sei->payload[j].payload_type !=
> +                    H264_SEI_TYPE_USER_DATA_REGISTERED)
> +                    continue;
> +                udr = &sei->payload[j].payload.user_data_registered;
> +                tag = AV_RB32(udr->data + 2);
> +                type_code = udr->data[6];
> +                if (tag != MKBETAG('G', 'A', '9', '4') || type_code != 3)
> +                    continue;
> +
> +                if (ctx->a53_cc == REMOVE) {
> +                    err = ff_cbs_h264_delete_sei_message(ctx->cbc, au,
> +                                                         &au->units[i], j);
> +                    if (err < 0) {
> +                        av_log(bsf, AV_LOG_ERROR, "Failed to delete "
> +                               "A53 CC SEI message.\n");
> +                        goto fail;
> +                    }
> +                    av_log(bsf, AV_LOG_WARNING, "A53 CC remove!.\n");
> +
> +                    --i;
> +                    break;
> +                }
> +
> +                // Extract.
> +                count = udr->data[7] & 0x1f;
> +                if (3 * count + 10 > udr->data_length) {
> +                    av_log(bsf, AV_LOG_ERROR, "Invalid A/53 closed caption "
> +                           "data: count %d overflows length %zu.\n",
> +                           count, udr->data_length);
> +                    continue;
> +                }
> +
> +                av_log(bsf, AV_LOG_WARNING, "A53 CC extract: %zu bytes.\n", udr->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,
> +                       udr->data + 9, 3 * count);
> +                a53_side_data_size += 3 * count;
> +            }
> +        }
> +    }
> +
>      err = ff_cbs_write_packet(ctx->cbc, out, au);
>      if (err < 0) {
>          av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
> @@ -535,6 +637,16 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *out)
>          }
>          displaymatrix_side_data = NULL;
>      }
> +    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;
> +    }
>
>      ctx->done_first_au = 1;
>
> @@ -542,6 +654,7 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *out)
>  fail:
>      ff_cbs_fragment_uninit(ctx->cbc, au);
>      av_freep(&displaymatrix_side_data);
> +    av_freep(&a53_side_data);
>
>      av_packet_free(&in);
>
> @@ -670,6 +783,14 @@ static const AVOption h264_metadata_options[] = {
>      { "vertical",   "Set ver_flip",
>          0, AV_OPT_TYPE_CONST, { .i64 = FLIP_VERTICAL },   .unit ="flip" },
>
> +    { "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" },
> +    { "insert",  NULL, 0, AV_OPT_TYPE_CONST, { .i64 = INSERT  }, .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" },
> +

Does extracting really make sense? Doesn't the data end up out of
order and basically unusable?

- Hendrik


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