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.rheinha...@gmail.com>
---
libavformat/matroskaenc.c | 47 ++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 21 deletions(-)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 5065b2adbd..8bbacf5cd3 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -337,7 +337,7 @@ 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)
@@ -348,13 +348,13 @@ 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. */
@@ -363,8 +363,11 @@ 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);
+ }
}
/**
@@ -449,7 +452,7 @@ 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;
@@ -476,7 +479,7 @@ 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);
@@ -1416,7 +1419,7 @@ 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;
}
@@ -1424,7 +1427,7 @@ 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;
@@ -1472,7 +1475,7 @@ 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;
@@ -1671,7 +1674,7 @@ 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;
}
@@ -1679,7 +1682,7 @@ 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;
@@ -1767,7 +1770,7 @@ 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;
}
@@ -1908,7 +1911,7 @@ 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);
@@ -2188,7 +2191,7 @@ 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);
}
@@ -2492,7 +2495,8 @@ 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);
@@ -2506,7 +2510,7 @@ 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;
@@ -2548,7 +2552,8 @@ 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);
@@ -2564,11 +2569,11 @@ 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) {
@@ -2598,7 +2603,7 @@ 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);
--
2.20.1
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