[FFmpeg-devel] [PATCH 4/5] avcodec/h264_metadata_bsf: add support for a/53 closed captions

[Aman Karmani <ffmpegagent@gmail.com>]

From: Aman Karmani <aman@tmm1.net>

Signed-off-by: Aman Karmani <aman@tmm1.net>
---
 doc/bitstream_filters.texi     |  11 +++
 libavcodec/Makefile            |   2 +-
 libavcodec/h264_metadata_bsf.c | 144 +++++++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+), 1 deletion(-)

diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index c036d37403..3d97f66315 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -243,6 +243,17 @@ ffmpeg -i hapqa_inputfile.mov -c copy -bsf:v hapqa_extract=texture=alpha -tag:v
 Modify metadata embedded in an H.264 stream.
 
 @table @option
+@item a53_cc
+Insert or remove registered userdata SEI NAL units containing A/53 closed captions.
+
+@table @samp
+@item pass
+@item insert
+@item remove
+@end table
+
+Default is pass.
+
 @item aud
 Insert or remove AUD NAL units in all access units of the stream.
 
diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 2a36a31ff2..9f97c9b5e5 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -1212,7 +1212,7 @@ OBJS-$(CONFIG_EXTRACT_EXTRADATA_BSF)      += extract_extradata_bsf.o    \
                                              av1_parse.o h2645_parse.o
 OBJS-$(CONFIG_FILTER_UNITS_BSF)           += filter_units_bsf.o
 OBJS-$(CONFIG_H264_METADATA_BSF)          += h264_metadata_bsf.o h264_levels.o \
-                                             h2645data.o
+                                             h2645data.o cbs_misc.o
 OBJS-$(CONFIG_H264_MP4TOANNEXB_BSF)       += h264_mp4toannexb_bsf.o
 OBJS-$(CONFIG_H264_REDUNDANT_PPS_BSF)     += h264_redundant_pps_bsf.o
 OBJS-$(CONFIG_HAPQA_EXTRACT_BSF)          += hapqa_extract_bsf.o hap.o
diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
index d318bf0cee..bbe74c3cee 100644
--- a/libavcodec/h264_metadata_bsf.c
+++ b/libavcodec/h264_metadata_bsf.c
@@ -26,6 +26,8 @@
 #include "cbs.h"
 #include "cbs_bsf.h"
 #include "cbs_h264.h"
+#include "cbs_misc.h"
+#include "cbs_sei.h"
 #include "h264.h"
 #include "h264_levels.h"
 #include "h264_sei.h"
@@ -81,6 +83,7 @@ typedef struct H264MetadataContext {
     H264RawSEIDisplayOrientation display_orientation_payload;
 
     int level;
+    int a53_cc;
 } H264MetadataContext;
 
 
@@ -463,6 +466,137 @@ static int h264_metadata_handle_display_orientation(AVBSFContext *bsf,
     return 0;
 }
 
+static int h264_metadata_handle_a53_cc(AVBSFContext *bsf, AVPacket *pkt,
+                                         CodedBitstreamFragment *au)
+{
+    H264MetadataContext *ctx = bsf->priv_data;
+    SEIRawMessage *message;
+    int err;
+
+    message = NULL;
+    while (ff_cbs_sei_find_message(ctx->common.output, au,
+                                   SEI_TYPE_USER_DATA_REGISTERED_ITU_T_T35,
+                                   &message) == 0) {
+        SEIRawUserDataRegistered *udr = message->payload;
+        A53UserData a53_ud;
+        uint8_t *a53_side_data = NULL;
+        size_t a53_side_data_size = 0;
+
+        if (udr->data_length < 2) {
+            // Too short to contain a provider code.
+            continue;
+        }
+
+        if (AV_RB16(udr->data) != 0x31) { // provider_code as atsc_provider_code
+            // Not ATSC.
+            continue;
+        }
+
+        // The first two bytes of the message is provider_code so we offset the data by that
+        err = ff_cbs_read_a53_user_data(ctx->common.output,
+                                        &a53_ud,
+                                        udr->data + 2,
+                                        udr->data_length - 2);
+        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;
+        }
+
+        err = ff_cbs_write_a53_cc_side_data(ctx->common.output,
+                                            &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");
+            return err;
+        }
+
+        if (a53_side_data) {
+            err = av_packet_add_side_data(pkt, 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");
+                av_freep(&a53_side_data);
+                return err;
+            }
+
+            if (ctx->a53_cc == BSF_ELEMENT_REMOVE ||
+                ctx->a53_cc == BSF_ELEMENT_INSERT) {
+                ff_cbs_sei_delete_message(ctx->common.output, au, message);
+
+                // Reset iteration
+                message = NULL;
+            }
+        }
+    }
+
+    if (ctx->a53_cc == BSF_ELEMENT_INSERT) {
+        uint8_t *data;
+        size_t size;
+        int offset = 0;
+
+        data = av_packet_get_side_data(pkt, AV_PKT_DATA_A53_CC, &size);
+        while (size > 0) {
+            A53UserData a53_ud;
+            int rsize = FFMIN(93, size);
+
+            err = ff_cbs_read_a53_cc_side_data(ctx->common.output, &a53_ud,
+                                               data + offset, rsize);
+            offset += rsize;
+            size -= rsize;
+            if (err < 0) {
+                av_log(bsf, AV_LOG_WARNING, "Invalid A/53 closed captions "
+                       "in packet side data dropped.\n");
+            } else {
+                AVBufferRef *udr_buf = av_buffer_allocz(sizeof(SEIRawUserDataRegistered));
+                SEIRawUserDataRegistered *udr = (SEIRawUserDataRegistered*)udr_buf->data;
+                size_t size = 9 + 3 * a53_ud.atsc.cc_data.cc_count;
+
+                udr->data_ref = av_buffer_allocz(2 + size);
+                if (!udr->data_ref) {
+                    return AVERROR(ENOMEM);
+                }
+                udr->data = udr->data_ref->data;
+                udr->data_length = udr->data_ref->size;
+
+                udr->itu_t_t35_country_code = 0xB5; // usa_country_code
+                AV_WB16(udr->data, 0x31);           // provider_code as atsc_provider_code
+
+                err = ff_cbs_write_a53_user_data(ctx->common.output, udr->data + 2,
+                                                 &size, &a53_ud);
+                if (err < 0) {
+                    av_log(bsf, AV_LOG_ERROR, "Failed to write "
+                           "A/53 user data.\n");
+                    av_buffer_unref(&udr->data_ref);
+                    av_buffer_unref(&udr_buf);
+                    return err;
+                }
+
+                err = ff_cbs_sei_add_message(ctx->common.output, au, 1,
+                                             SEI_TYPE_USER_DATA_REGISTERED_ITU_T_T35,
+                                             udr, udr_buf);
+                if (err < 0) {
+                    av_log(bsf, AV_LOG_ERROR, "Failed to add A/53 user data "
+                           "SEI message to access unit.\n");
+                    av_buffer_unref(&udr->data_ref);
+                    av_buffer_unref(&udr_buf);
+                    return err;
+                }
+            }
+        }
+    }
+
+    return 0;
+}
+
 static int h264_metadata_update_fragment(AVBSFContext *bsf, AVPacket *pkt,
                                          CodedBitstreamFragment *au)
 {
@@ -533,6 +667,12 @@ static int h264_metadata_update_fragment(AVBSFContext *bsf, AVPacket *pkt,
             return err;
     }
 
+    if (pkt && ctx->a53_cc != BSF_ELEMENT_PASS) {
+        err = h264_metadata_handle_a53_cc(bsf, pkt, au);
+        if (err < 0)
+            return err;
+    }
+
     if (pkt)
         ctx->done_first_au = 1;
 
@@ -696,6 +836,10 @@ static const AVOption h264_metadata_options[] = {
     { LEVEL("6.2", 62) },
 #undef LEVEL
 
+    BSF_ELEMENT_OPTIONS_PIRE("a53_cc",
+                             "A/53 Closed Captions in SEI NAL units",
+                             a53_cc, FLAGS),
+
     { NULL }
 };
 
-- 
ffmpeg-codebot

_______________________________________________
ffmpeg-devel mailing list
ffmpeg-devel@ffmpeg.org
https://ffmpeg.org/mailman/listinfo/ffmpeg-devel

To unsubscribe, visit link above, or email
ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".