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

[Mark Thompson]

---
 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" },
+
     { NULL }
 };
 
-- 
2.16.1