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avformat/matroskaenc: Stop reallocating of Cluster buffer

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The Matroska muxer uses a dynamic buffer to buffer the content of
Clusters before eventually writing them. Up until now, each time a
Cluster was written, the dynamic buffer was closed, i.e. freed; now it
is only reset, saving allocations of the AVIOContext itself, its opaque
as well as most of the reallocations of the buffer.

This is advantageous performance-wise, in particular on systems where
reallocations are slow (namely Windows). The following table shows the
decicyles for writing a frame on Linux (Ubuntu 19.10) and Windows (7)
on an x64 Haswell (to /dev/null on Linux, to stdout which is discarded
on Windows (the default values of the size and duration of clusters for
seekable output have been explicitly set in this case); in all tests,
writing CRC-32 values has been disabled in all tests; calls to the muxer's
write_packet function in write_packet() in libavformat/mux.c have been
timed; each of the following tests has been repeated 50 times):

    | Windows before | Windows after | Linux before | Linux after
_________________________________________________________________
 A  |     979437     |    192304     |    259500    |   183320
 B  |     715936     |    155648     |    152786    |   130879
 C  |     265115     |     56034     |     78496    |    53243
 D  |     386224     |     80307     |    128894    |    75354
 E  |      21732     |     10695     |     11320    |     9801

(A is a 10.2 mb/s file with a GOP length of 2s, amounting to an average
Cluster size of about 2.5 MiB; the average Cluster size of B is 1.1 MiB;
for C it is 2.35 MiB, for D it is 0.46 MiB; for E - a file with just a
single audio track of 158kb/s resulting in a Cluster size of about 100
kB, the relative gains were the smallest, probably because of the small
Cluster size.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2019-12-29 01:01:52 +01:00
parent e1488700a2
commit 4aa0665f39
1 changed files with 26 additions and 21 deletions
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47
libavformat/matroskaenc.c
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@ -330,7 +330,7 @@ static int start_ebml_master_crc32(AVIOContext **dyn_cp, MatroskaMuxContext *mkv
{
int ret;
if ((ret = avio_open_dyn_buf(dyn_cp)) < 0)
if (!*dyn_cp && (ret = avio_open_dyn_buf(dyn_cp)) < 0)
return ret;
if (mkv->write_crc)
@ -341,13 +341,13 @@ static int start_ebml_master_crc32(AVIOContext **dyn_cp, MatroskaMuxContext *mkv
static void end_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp,
MatroskaMuxContext *mkv, uint32_t id,
int length_size)
int length_size, int keep_buffer)
{
uint8_t *buf, crc[4];
int size, skip = 0;
put_ebml_id(pb, id);
size = avio_close_dyn_buf(*dyn_cp, &buf);
size = avio_get_dyn_buf(*dyn_cp, &buf);
put_ebml_num(pb, size, length_size);
if (mkv->write_crc) {
skip = 6; /* Skip reserved 6-byte long void element from the dynamic buffer. */
@ -356,8 +356,11 @@ static void end_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp,
}
avio_write(pb, buf + skip, size - skip);
av_free(buf);
*dyn_cp = NULL;
if (keep_buffer) {
ffio_reset_dyn_buf(*dyn_cp);
} else {
ffio_free_dyn_buf(dyn_cp);
}
}
/**
@ -443,7 +446,7 @@ static void mkv_add_seekhead_entry(MatroskaMuxContext *mkv, uint32_t elementid,
static int mkv_write_seekhead(AVIOContext *pb, MatroskaMuxContext *mkv,
int error_on_seek_failure, int64_t destpos)
{
AVIOContext *dyn_cp;
AVIOContext *dyn_cp = NULL;
mkv_seekhead *seekhead = &mkv->seekhead;
int64_t remaining, ret64;
int i, ret;
@ -467,7 +470,7 @@ static int mkv_write_seekhead(AVIOContext *pb, MatroskaMuxContext *mkv,
put_ebml_uint(dyn_cp, MATROSKA_ID_SEEKPOSITION, entry->segmentpos);
end_ebml_master(dyn_cp, seekentry);
}
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_SEEKHEAD, 0);
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_SEEKHEAD, 0, 0);
remaining = seekhead->filepos + seekhead->reserved_size - avio_tell(pb);
put_ebml_void(pb, remaining);
@ -1379,7 +1382,7 @@ static int mkv_write_tracks(AVFormatContext *s)
end_ebml_master_crc32_preliminary(pb, mkv->tracks_bc,
MATROSKA_ID_TRACKS, &mkv->tracks_pos);
else
end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS, 0);
end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS, 0, 0);
return 0;
}
@ -1387,7 +1390,7 @@ static int mkv_write_tracks(AVFormatContext *s)
static int mkv_write_chapters(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
AVIOContext *dyn_cp, *pb = s->pb;
AVIOContext *dyn_cp = NULL, *pb = s->pb;
ebml_master editionentry;
AVRational scale = {1, 1E9};
int i, ret;
@ -1435,7 +1438,7 @@ static int mkv_write_chapters(AVFormatContext *s)
end_ebml_master(dyn_cp, chapteratom);
}
end_ebml_master(dyn_cp, editionentry);
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CHAPTERS, 0);
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CHAPTERS, 0, 0);
mkv->wrote_chapters = 1;
return 0;
@ -1634,7 +1637,7 @@ static int mkv_write_tags(AVFormatContext *s)
end_ebml_master_crc32_preliminary(s->pb, mkv->tags_bc,
MATROSKA_ID_TAGS, &mkv->tags_pos);
else
end_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS, 0);
end_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS, 0, 0);
}
return 0;
}
@ -1642,7 +1645,7 @@ static int mkv_write_tags(AVFormatContext *s)
static int mkv_write_attachments(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
AVIOContext *dyn_cp, *pb = s->pb;
AVIOContext *dyn_cp = NULL, *pb = s->pb;
AVLFG c;
int i, ret;
@ -1730,7 +1733,7 @@ static int mkv_write_attachments(AVFormatContext *s)
mkv->attachments->entries[mkv->attachments->num_entries].stream_idx = i;
mkv->attachments->entries[mkv->attachments->num_entries++].fileuid = fileuid;
}
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_ATTACHMENTS, 0);
end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_ATTACHMENTS, 0, 0);
return 0;
}
@ -1871,7 +1874,7 @@ static int mkv_write_header(AVFormatContext *s)
end_ebml_master_crc32_preliminary(s->pb, mkv->info_bc,
MATROSKA_ID_INFO, &mkv->info_pos);
else
end_ebml_master_crc32(s->pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO, 0);
end_ebml_master_crc32(s->pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO, 0, 0);
pb = s->pb;
ret = mkv_write_tracks(s);
@ -2159,7 +2162,7 @@ static void mkv_end_cluster(AVFormatContext *s)
{
MatroskaMuxContext *mkv = s->priv_data;
end_ebml_master_crc32(s->pb, &mkv->cluster_bc, mkv, MATROSKA_ID_CLUSTER, 0);
end_ebml_master_crc32(s->pb, &mkv->cluster_bc, mkv, MATROSKA_ID_CLUSTER, 0, 1);
mkv->cluster_pos = -1;
avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_FLUSH_POINT);
}
@ -2465,7 +2468,8 @@ static int mkv_write_trailer(AVFormatContext *s)
}
if (mkv->cluster_bc) {
end_ebml_master_crc32(pb, &mkv->cluster_bc, mkv, MATROSKA_ID_CLUSTER, 0);
end_ebml_master_crc32(pb, &mkv->cluster_bc, mkv,
MATROSKA_ID_CLUSTER, 0, 0);
}
ret = mkv_write_chapters(s);
@ -2479,7 +2483,7 @@ static int mkv_write_trailer(AVFormatContext *s)
endpos = avio_tell(pb);
if (mkv->cues.num_entries) {
AVIOContext *cues;
AVIOContext *cues = NULL;
uint64_t size;
int64_t cuespos = endpos;
int length_size = 0;
@ -2525,7 +2529,8 @@ static int mkv_write_trailer(AVFormatContext *s)
}
}
mkv_add_seekhead_entry(mkv, MATROSKA_ID_CUES, cuespos);
end_ebml_master_crc32(pb, &cues, mkv, MATROSKA_ID_CUES, length_size);
end_ebml_master_crc32(pb, &cues, mkv, MATROSKA_ID_CUES,
length_size, 0);
if (mkv->reserve_cues_space) {
if (size < mkv->reserve_cues_space)
put_ebml_void(pb, mkv->reserve_cues_space - size);
@ -2542,11 +2547,11 @@ static int mkv_write_trailer(AVFormatContext *s)
av_log(s, AV_LOG_DEBUG, "end duration = %" PRIu64 "\n", mkv->duration);
avio_seek(mkv->info_bc, mkv->duration_offset, SEEK_SET);
put_ebml_float(mkv->info_bc, MATROSKA_ID_DURATION, mkv->duration);
end_ebml_master_crc32(pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO, 0);
end_ebml_master_crc32(pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO, 0, 0);
// write tracks master
avio_seek(pb, mkv->tracks_pos, SEEK_SET);
end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS, 0);
end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS, 0, 0);
// update stream durations
if (!mkv->is_live) {
@ -2576,7 +2581,7 @@ static int mkv_write_trailer(AVFormatContext *s)
}
if (mkv->tags_bc && !mkv->is_live) {
avio_seek(pb, mkv->tags_pos, SEEK_SET);
end_ebml_master_crc32(pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS, 0);
end_ebml_master_crc32(pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS, 0, 0);
}
avio_seek(pb, endpos, SEEK_SET);