Currently, the Matroska muxer reallocates its array of index entries
each time another entry is added. This is bad performance-wise,
especially on Windows where reallocations are slow. This is solved
by switching to av_fast_realloc_array() which ensures that actual
reallocations will happen only seldomly.
For an (admittedly extreme) example which consists of looping a video
consisting of a single keyframe of size 4KB 540000 times this improved
the time for writing a frame from 23524201 decicycles (516466 runs,
7822 skips) to 225240 decicycles (522122 runs, 2166 skips) on Windows.
(Writing CRC-32 elements was disabled for these tests.)
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
The guy from ticket #8109 will probably be quite happy about this.
libavformat/matroskaenc.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 469b604de6..72d19a9f5a 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -88,7 +88,8 @@ typedef struct mkv_cuepoint {
typedef struct mkv_cues {
int64_t segment_offset;
mkv_cuepoint *entries;
- int num_entries;
+ unsigned num_entries;
+ unsigned allocated_entries;
} mkv_cues;
typedef struct mkv_track {
@@ -171,7 +172,7 @@ typedef struct MatroskaMuxContext {
/** per-cuepoint-track - 5 1-byte EBML IDs, 5 1-byte EBML sizes, 3 8-byte uint
max
* and one 1-byte uint for the track number (this assumes MAX_TRACKS to be <=
255) */
-#define MAX_CUETRACKPOS_SIZE 35
+#define MAX_CUETRACKPOS_SIZE 35LL
/** per-cuepoint - 1 1-byte EBML ID, 1 1-byte EBML size, 8-byte uint max */
#define MAX_CUEPOINT_CONTENT_SIZE(num_tracks) 10 + MAX_CUETRACKPOS_SIZE *
num_tracks
@@ -540,7 +541,8 @@ static int mkv_add_cuepoint(mkv_cues *cues, int stream, int
tracknum, int64_t ts
if (ts < 0)
return 0;
- entries = av_realloc_array(entries, cues->num_entries + 1,
sizeof(mkv_cuepoint));
+ entries = av_fast_realloc_array(entries, &cues->allocated_entries,
+ cues->num_entries + 1,
sizeof(mkv_cuepoint));
if (!entries)
return AVERROR(ENOMEM);
cues->entries = entries;
@@ -560,21 +562,21 @@ static int64_t mkv_write_cues(AVFormatContext *s,
mkv_cues *cues, mkv_track *tra
MatroskaMuxContext *mkv = s->priv_data;
AVIOContext *dyn_cp, *pb = s->pb;
int64_t currentpos;
- int i, j, ret;
+ int ret;
currentpos = avio_tell(pb);
ret = start_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CUES);
if (ret < 0)
return ret;
- for (i = 0; i < cues->num_entries; i++) {
+ for (unsigned i = 0; i < cues->num_entries; i++) {
ebml_master cuepoint, track_positions;
mkv_cuepoint *entry = &cues->entries[i];
uint64_t pts = entry->pts;
- int ctp_nb = 0;
+ unsigned ctp_nb = 0, j;
// Calculate the number of entries, so we know the element size
- for (j = 0; j < num_tracks; j++)
+ for (int j = 0; j < num_tracks; j++)
tracks[j].has_cue = 0;
for (j = 0; j < cues->num_entries - i && entry[j].pts == pts; j++) {
int idx = entry[j].stream_idx;
@@ -591,7 +593,7 @@ static int64_t mkv_write_cues(AVFormatContext *s, mkv_cues
*cues, mkv_track *tra
// put all the entries from different tracks that have the exact same
// timestamp into the same CuePoint
- for (j = 0; j < num_tracks; j++)
+ for (int j = 0; j < num_tracks; j++)
tracks[j].has_cue = 0;
for (j = 0; j < cues->num_entries - i && entry[j].pts == pts; j++) {
int idx = entry[j].stream_idx;
--
2.20.1
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