>From f7aeb160a8ba2e2eefa6206af2ff5179a88f7343 Mon Sep 17 00:00:00 2001
From: Jerome Martinez <[email protected]>
Date: Thu, 4 Sep 2025 20:18:08 +0200
Subject: [PATCH 7/7] matroskaenc: write timecode in BlockAddition
---
libavformat/matroskaenc.c | 45 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index d304b63663..aa7b8f4443 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -60,6 +60,7 @@
#include "libavutil/rational.h"
#include "libavutil/samplefmt.h"
#include "libavutil/stereo3d.h"
+#include "libavutil/timecode.h"
#include "libavcodec/av1.h"
#include "libavcodec/bytestream.h"
@@ -81,6 +82,9 @@
#define MAX_SUPPORTED_EBML_LENGTH FFMIN(MAX_EBML_LENGTH, INT_MAX)
#define MAX_MATROSKA_BLOCK_ADD_ITU_T_T35 1 /* currently only 1 such element is
supported */
+#define MAX_MATROSKA_BLOCK_ADD_SMPTE_12M 64 /* balance between intermediate
buffer size and reality of non existence if so many timecodes streams for one
content */
+
+#define MATROSKA_BLOCK_ADD_ID_SMPTE_12M 101 /* arbitrary value */
#define MODE_MATROSKAv2 0x01
#define MODE_WEBM 0x02
@@ -199,6 +203,7 @@ typedef struct mkv_track {
int64_t duration_offset;
uint64_t max_blockaddid;
int itu_t_t35_count;
+ int timecode_count;
int64_t blockadditionmapping_offset;
int codecpriv_offset;
unsigned codecpriv_size; ///< size reserved for CodecPrivate
excluding header+length field
@@ -2825,11 +2830,12 @@ static int mkv_write_block(void *logctx,
MatroskaMuxContext *mkv,
int force_blockgroup, int64_t relative_packet_pos)
{
uint8_t t35_buf[6 + AV_HDR_PLUS_MAX_PAYLOAD_SIZE];
+ uint8_t timecode_buf[MAX_MATROSKA_BLOCK_ADD_SMPTE_12M][8];
uint8_t *side_data;
size_t side_data_size;
uint64_t additional_id;
unsigned track_number = track->track_num;
- EBML_WRITER(11 + MAX_MATROSKA_BLOCK_ADD_ITU_T_T35);
+ EBML_WRITER(11 + MAX_MATROSKA_BLOCK_ADD_ITU_T_T35 +
MAX_MATROSKA_BLOCK_ADD_SMPTE_12M);
int ret;
mkv->cur_block.track = track;
@@ -2908,6 +2914,36 @@ static int mkv_write_block(void *logctx,
MatroskaMuxContext *mkv,
}
}
+ // Extract timecode from side data and write as BlockAdditional
+ if (par->codec_type == AVMEDIA_TYPE_VIDEO) {
+ side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_S12M_TIMECODE,
&side_data_size);
+ if (side_data && side_data_size >= sizeof(uint64_t)) {
+ uint64_t *side_data_64 = (uint64_t*)side_data;
+ uint64_t count = side_data_64[0];
+ if (side_data_size / sizeof(uint64_t) - 1 >= count ) {
+ uint64_t written_count = count;
+ side_data_64++;
+ if (count > MAX_MATROSKA_BLOCK_ADD_SMPTE_12M) {
+ if (count > track->timecode_count) {
+ av_log(logctx, AV_LOG_WARNING, "Too many SMPTE
timecode streams in side data, discarding %"PRIu64" timecode streams.\n", count
- MAX_MATROSKA_BLOCK_ADD_SMPTE_12M);
+ }
+ written_count = MAX_MATROSKA_BLOCK_ADD_SMPTE_12M;
+ }
+ for (uint64_t i = 0; i < written_count; i++) {
+ uint64_t tc = side_data_64[i];
+ uint8_t *payload = timecode_buf[i];
+ AV_WB64(payload, tc);
+ av_log(logctx, AV_LOG_DEBUG, "Writing SMPTE timecode from
side data, pos %"PRIu64", to BlockAdditional: 0x%016lX (RFC 5484)\n", i + 1,
tc);
+
+ int blockaddid = MATROSKA_BLOCK_ADD_ID_SMPTE_12M + i;
+ mkv_write_blockadditional(&writer, payload, 8, blockaddid);
+ track->max_blockaddid = FFMAX(track->max_blockaddid,
blockaddid);
+ }
+ track->timecode_count = FFMAX(track->timecode_count, count);
+ }
+ }
+ }
+
ebml_writer_close_or_discard_master(&writer);
if (!force_blockgroup && writer.nb_elements == 2) {
@@ -3320,11 +3356,15 @@ after_cues:
int max_block_add_id_count = 0;
int max_block_add_id_size = 3 +
uint_size(track->max_blockaddid);
int block_type_t35_count = 0;
+ int block_type_timecode_count = 0;
if (!track->max_blockaddid)
continue;
/* check what is possible to write in the reserved space, in
priority order */
+ for (int i = 0; i < track->timecode_count; i++) {
+ block_type_timecode_count +=
mkv_simulate_blockadditional_header(s, &remaining_video_track_space,
MATROSKA_BLOCK_ADD_ID_TYPE_SMPTE_12M, MATROSKA_BLOCK_ADD_ID_SMPTE_12M + i);
+ }
for (int i = 0; i < track->itu_t_t35_count; i++) {
block_type_t35_count +=
mkv_simulate_blockadditional_header(s, &remaining_video_track_space,
MATROSKA_BLOCK_ADD_ID_TYPE_ITU_T_T35, MATROSKA_BLOCK_ADD_ID_TYPE_ITU_T_T35);
}
@@ -3344,6 +3384,9 @@ after_cues:
for (int i = 0; i < block_type_t35_count; i++) {
mkv_write_blockadditional_header(s,
MATROSKA_BLOCK_ADD_ID_TYPE_ITU_T_T35, MATROSKA_BLOCK_ADD_ID_ITU_T_T35);
}
+ for (int i = 0; i < block_type_timecode_count; i++) {
+ mkv_write_blockadditional_header(s,
MATROSKA_BLOCK_ADD_ID_TYPE_SMPTE_12M, MATROSKA_BLOCK_ADD_ID_SMPTE_12M + i);
+ }
if (remaining_video_track_space > 1) {
put_ebml_void(track_bc, remaining_video_track_space);
}
--
2.46.0.windows.1
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