[FFmpeg-cvslog] avformat/movenc: support writing more than one STSD entry per track
James Almer
git at videolan.org
Wed Jul 30 23:54:27 EEST 2025
ffmpeg | branch: master | James Almer <jamrial at gmail.com> | Sun Jul 27 18:51:06 2025 -0300| [4eca8df8b8143f9c8daec07fa0bc9ff7e2babcb1] | committer: James Almer
avformat/movenc: support writing more than one STSD entry per track
If a packet contains new extradata within a side data entry, save for
specific cases it means the coded stream changed. If ignored, upon
demuxing every packet from then onwards may be undecodable.
Signed-off-by: James Almer <jamrial at gmail.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=4eca8df8b8143f9c8daec07fa0bc9ff7e2babcb1
---
libavformat/movenc.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++----
libavformat/movenc.h | 1 +
2 files changed, 50 insertions(+), 4 deletions(-)
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index 96fb31655d..743d360ace 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -247,7 +247,7 @@ static int mov_write_stsz_tag(AVIOContext *pb, MOVTrack *track)
/* Sample to chunk atom */
static int mov_write_stsc_tag(AVIOContext *pb, MOVTrack *track)
{
- int index = 0, oldval = -1, i;
+ int index = 0, oldidx = -1, oldval = -1, i;
int64_t entryPos, curpos;
int64_t pos = avio_tell(pb);
@@ -257,11 +257,13 @@ static int mov_write_stsc_tag(AVIOContext *pb, MOVTrack *track)
entryPos = avio_tell(pb);
avio_wb32(pb, track->chunkCount); // entry count
for (i = 0; i < track->entry; i++) {
- if (oldval != track->cluster[i].samples_in_chunk && track->cluster[i].chunkNum) {
+ if ((oldval != track->cluster[i].samples_in_chunk ||
+ oldidx != track->cluster[i].stsd_index) && track->cluster[i].chunkNum) {
avio_wb32(pb, track->cluster[i].chunkNum); // first chunk
avio_wb32(pb, track->cluster[i].samples_in_chunk); // samples per chunk
- avio_wb32(pb, 0x1); // sample description index
+ avio_wb32(pb, track->cluster[i].stsd_index + 1); // sample description index
oldval = track->cluster[i].samples_in_chunk;
+ oldidx = track->cluster[i].stsd_index;
index++;
}
}
@@ -3053,8 +3055,12 @@ static int mov_write_stsd_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContext
avio_wb32(pb, 0); /* size */
ffio_wfourcc(pb, "stsd");
avio_wb32(pb, 0); /* version & flags */
- avio_wb32(pb, 1); /* entry count */
+ avio_wb32(pb, track->stsd_count);
+ int stsd_index_back = track->last_stsd_index;
+ for (track->last_stsd_index = 0;
+ track->last_stsd_index < track->stsd_count;
+ track->last_stsd_index++) {
if (track->par->codec_type == AVMEDIA_TYPE_VIDEO)
ret = mov_write_video_tag(s, pb, mov, track);
else if (track->par->codec_type == AVMEDIA_TYPE_AUDIO)
@@ -3070,6 +3076,9 @@ static int mov_write_stsd_tag(AVFormatContext *s, AVIOContext *pb, MOVMuxContext
if (ret < 0)
return ret;
+ }
+
+ track->last_stsd_index = stsd_index_back;
return update_size(pb, pos);
}
@@ -5040,6 +5049,7 @@ static void build_chunks(MOVTrack *trk)
trk->chunkCount = 1;
for (i = 1; i<trk->entry; i++){
if (chunk->pos + chunkSize == trk->cluster[i].pos &&
+ chunk->stsd_index == trk->cluster[i].stsd_index &&
chunkSize + trk->cluster[i].size < (1<<20)){
chunkSize += trk->cluster[i].size;
chunk->samples_in_chunk += trk->cluster[i].entries;
@@ -6761,6 +6771,39 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
memset(trk->extradata[0] + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
}
+ const AVPacketSideData *sd = av_packet_side_data_get(pkt->side_data, pkt->side_data_elems, AV_PKT_DATA_NEW_EXTRADATA);
+ if (pkt->size && sd && sd->size > 0) {
+ int i;
+ for (i = 0; i < trk->stsd_count; i++) {
+ if (trk->extradata_size[i] == sd->size && !memcmp(trk->extradata[i], sd->data, sd->size))
+ break;
+ }
+
+ if (i < trk->stsd_count)
+ trk->last_stsd_index = i;
+ else if (trk->stsd_count <= INT_MAX - 1) {
+ int new_count = trk->stsd_count + 1;
+ uint8_t **extradata = av_realloc_array(trk->extradata, new_count, sizeof(*trk->extradata));
+ if (!extradata)
+ return AVERROR(ENOMEM);
+ trk->extradata = extradata;
+
+ int *extradata_size = av_realloc_array(trk->extradata_size, new_count, sizeof(*trk->extradata_size));
+ if (!extradata_size)
+ return AVERROR(ENOMEM);
+ trk->extradata_size = extradata_size;
+
+ trk->extradata[trk->stsd_count] = av_memdup(sd->data, sd->size);
+ if (!trk->extradata[trk->stsd_count])
+ return AVERROR(ENOMEM);
+
+ trk->extradata_size[trk->stsd_count] = sd->size;
+ trk->last_stsd_index = trk->stsd_count;
+ trk->stsd_count = new_count;
+ } else
+ return AVERROR(ENOMEM);
+ }
+
if (par->codec_id == AV_CODEC_ID_AAC && pkt->size > 2 &&
(AV_RB16(pkt->data) & 0xfff0) == 0xfff0) {
if (!trk->st->nb_frames) {
@@ -6912,6 +6955,7 @@ int ff_mov_write_packet(AVFormatContext *s, AVPacket *pkt)
}
trk->cluster[trk->entry].pos = avio_tell(pb) - size;
+ trk->cluster[trk->entry].stsd_index = trk->last_stsd_index;
trk->cluster[trk->entry].samples_in_chunk = samples_in_chunk;
trk->cluster[trk->entry].chunkNum = 0;
trk->cluster[trk->entry].size = size;
@@ -7594,6 +7638,7 @@ static void mov_free(AVFormatContext *s)
for (int j = 0; j < track->stsd_count; j++)
av_freep(&track->extradata[j]);
av_freep(&track->extradata);
+ av_freep(&track->extradata_size);
ff_mov_cenc_free(&track->cenc);
ffio_free_dyn_buf(&track->mdat_buf);
diff --git a/libavformat/movenc.h b/libavformat/movenc.h
index 4c20571e67..942ad905f7 100644
--- a/libavformat/movenc.h
+++ b/libavformat/movenc.h
@@ -50,6 +50,7 @@ typedef struct MOVIentry {
int64_t dts;
int64_t pts;
unsigned int size;
+ unsigned int stsd_index;
unsigned int samples_in_chunk;
unsigned int chunkNum; ///< Chunk number if the current entry is a chunk start otherwise 0
unsigned int entries;
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