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avformat/matroskaenc: Remove special code for writing subtitles

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Once upon a time, mkv_write_block() only wrote a (Simple)Block,
not a BlockGroup which is needed for subtitles to convey
the duration. But with the introduction of support for writing
BlockAdditions and DiscardPadding (both of which require a BlockGroup),
mkv_write_block() can also open and close a BlockGroup of its own. This
naturally led to some code duplication which is removed in this commit.

This new code leads to one regression: It always uses eight bytes for
the BlockGroup's length field, whereas the earlier code usually used the
lowest amount of bytes needed. This will be fixed in a future commit.

This temporary regression is also the reason for changes to the
binsub-mksenc and matroska-zero-length-block fate tests.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
release/5.1
Andreas Rheinhardt 5 years ago
parent d328467dd3
commit 03d31ef39c
3 changed files with 21 additions and 27 deletions
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  1. 42
      libavformat/matroskaenc.c
  2. 2
      tests/ref/fate/binsub-mksenc
  3. 4
      tests/ref/fate/matroska-zero-length-block

42
libavformat/matroskaenc.c
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@ -2418,7 +2418,7 @@ static int mkv_reformat_av1(MatroskaMuxContext *mkv, AVIOContext *pb,
}
static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
uint32_t blockid, const AVPacket *pkt, int keyframe)
const AVPacket *pkt, int keyframe, uint64_t duration)
{
MatroskaMuxContext *mkv = s->priv_data;
AVCodecParameters *par = s->streams[pkt->stream_index]->codecpar;
@ -2428,10 +2428,10 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
int err = 0, offset = 0, size = pkt->size;
int64_t ts = track->write_dts ? pkt->dts : pkt->pts;
uint64_t additional_id;
uint32_t blockid = MATROSKA_ID_SIMPLEBLOCK;
int64_t discard_padding = 0;
unsigned track_number = track->track_num;
ebml_master block_group, block_additions, block_more;
int blockgroup_already_opened = blockid == MATROSKA_ID_BLOCK;
ts += track->ts_offset;
@ -2466,7 +2466,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
side_data = av_packet_get_side_data(pkt,
AV_PKT_DATA_SKIP_SAMPLES,
&side_data_size);
if (side_data && side_data_size >= 10 && !blockgroup_already_opened) {
if (side_data && side_data_size >= 10) {
discard_padding = av_rescale_q(AV_RL32(side_data + 4),
(AVRational){1, par->sample_rate},
(AVRational){1, 1000000000});
@ -2477,8 +2477,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
&side_data_size);
if (side_data) {
// Only the Codec-specific BlockMore (id == 1) is currently supported.
if (side_data_size < 8 || (additional_id = AV_RB64(side_data)) != 1 ||
blockgroup_already_opened) {
if (side_data_size < 8 || (additional_id = AV_RB64(side_data)) != 1) {
side_data_size = 0;
} else {
side_data += 8;
@ -2486,7 +2485,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
}
}
if (side_data_size || discard_padding) {
if (side_data_size || discard_padding || duration) {
block_group = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP, 0);
blockid = MATROSKA_ID_BLOCK;
}
@ -2502,6 +2501,9 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
avio_write(pb, data + offset, size);
}
if (duration)
put_ebml_uint(pb, MATROSKA_ID_BLOCKDURATION, duration);
if (blockid == MATROSKA_ID_BLOCK && !keyframe)
put_ebml_sint(pb, MATROSKA_ID_BLOCKREFERENCE, track->last_timestamp - ts);
track->last_timestamp = ts;
@ -2520,7 +2522,7 @@ static int mkv_write_block(AVFormatContext *s, AVIOContext *pb,
end_ebml_master(pb, block_more);
end_ebml_master(pb, block_additions);
}
if (side_data_size || discard_padding)
if (blockid == MATROSKA_ID_BLOCK)
end_ebml_master(pb, block_group);
return 0;
@ -2697,8 +2699,11 @@ static int mkv_write_packet_internal(AVFormatContext *s, const AVPacket *pkt)
AVIOContext *pb;
AVCodecParameters *par = s->streams[pkt->stream_index]->codecpar;
mkv_track *track = &mkv->tracks[pkt->stream_index];
int keyframe = !!(pkt->flags & AV_PKT_FLAG_KEY);
int64_t duration = pkt->duration;
int is_sub = par->codec_type == AVMEDIA_TYPE_SUBTITLE;
/* All subtitle blocks are considered to be keyframes. */
int keyframe = is_sub || !!(pkt->flags & AV_PKT_FLAG_KEY);
int64_t duration = FFMAX(pkt->duration, 0);
int64_t write_duration = is_sub ? duration : 0;
int ret;
int64_t ts = track->write_dts ? pkt->dts : pkt->pts;
int64_t relative_packet_pos;
@ -2735,9 +2740,8 @@ static int mkv_write_packet_internal(AVFormatContext *s, const AVPacket *pkt)
relative_packet_pos = avio_tell(pb);
if (par->codec_type != AVMEDIA_TYPE_SUBTITLE ||
(par->codec_id != AV_CODEC_ID_WEBVTT && duration <= 0)) {
ret = mkv_write_block(s, pb, MATROSKA_ID_SIMPLEBLOCK, pkt, keyframe);
if (par->codec_id != AV_CODEC_ID_WEBVTT) {
ret = mkv_write_block(s, pb, pkt, keyframe, write_duration);
if (ret < 0)
return ret;
if (keyframe && IS_SEEKABLE(s->pb, mkv) &&
@ -2745,26 +2749,16 @@ static int mkv_write_packet_internal(AVFormatContext *s, const AVPacket *pkt)
par->codec_type == AVMEDIA_TYPE_SUBTITLE ||
!mkv->have_video && !track->has_cue)) {
ret = mkv_add_cuepoint(mkv, pkt->stream_index, ts,
mkv->cluster_pos, relative_packet_pos, 0);
mkv->cluster_pos, relative_packet_pos,
write_duration);
if (ret < 0)
return ret;
track->has_cue = 1;
}
} else {
if (par->codec_id == AV_CODEC_ID_WEBVTT) {
ret = mkv_write_vtt_blocks(s, pb, pkt);
if (ret < 0)
return ret;
} else {
ebml_master blockgroup = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP,
mkv_blockgroup_size(pkt->size,
track->track_num_size));
/* All subtitle blocks are considered to be keyframes. */
mkv_write_block(s, pb, MATROSKA_ID_BLOCK, pkt, 1);
put_ebml_uint(pb, MATROSKA_ID_BLOCKDURATION, duration);
end_ebml_master(pb, blockgroup);
}
if (IS_SEEKABLE(s->pb, mkv)) {
ret = mkv_add_cuepoint(mkv, pkt->stream_index, ts,

2
tests/ref/fate/binsub-mksenc
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@ -1 +1 @@
490b1b4beb4a614c06004609039ce779
9dd2ff92a3da9fb50405db3d05e41042

4
tests/ref/fate/matroska-zero-length-block
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@ -1,5 +1,5 @@
f37ba7e8a30eaa33c1fd0ef77447fb41 *tests/data/fate/matroska-zero-length-block.matroska
636 tests/data/fate/matroska-zero-length-block.matroska
c09d3b89ed0795817d671deb041fca1b *tests/data/fate/matroska-zero-length-block.matroska
650 tests/data/fate/matroska-zero-length-block.matroska
#tb 0: 1/1000
#media_type 0: subtitle
#codec_id 0: subrip

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