From: Michael Fabian 'Xaymar' Dirks <michael.di...@xaymar.com>
Adds "timestamp_precision" to the available options for Matroska muxing.
The option enables users and developers to change the precision of the
time stamps in the Matroska container up to 1 nanosecond, which can aid
with the proper detection of constant and variable rate content.
Work-around fix for: 259, 6406, 7927, 8909 and 9124.
Signed-off-by: Michael Fabian 'Xaymar' Dirks <michael.di...@xaymar.com>
---
doc/muxers.texi | 8 ++++++++
libavformat/matroskaenc.c | 33 ++++++++++++++++++++++++++-------
2 files changed, 34 insertions(+), 7 deletions(-)
diff --git a/doc/muxers.texi b/doc/muxers.texi
index e1c6ad0829..8655be94ff 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -1583,6 +1583,14 @@ bitmap is stored bottom-up. Note that this option does
not flip the bitmap
which has to be done manually beforehand, e.g. by using the vflip filter.
Default is @var{false} and indicates bitmap is stored top down.
+@item timestamp_precision
+Sets the timestamp precision up to 1 nanosecond for Matroska/WebM, which can
+improve detection of constant rate content in demuxers. Note that some poorly
+implemented demuxers may require a timestamp precision of 1 millisecond, so
+increasing it past that point may result in playback issues. Higher precision
+also reduces the maximum possible timestamp significantly.
+Default is @var{1/1000} (1 millisecond).
+
@end table
@anchor{md5}
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 186a25d920..1b911a648c 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -158,6 +158,8 @@ typedef struct MatroskaMuxContext {
int default_mode;
uint32_t segment_uid[4];
+
+ AVRational time_base;
} MatroskaMuxContext;
/** 2 bytes * 7 for EBML IDs, 7 1-byte EBML lengths, 6 1-byte uint,
@@ -1814,6 +1816,7 @@ static int mkv_write_header(AVFormatContext *s)
const AVDictionaryEntry *tag;
int ret, i, version = 2;
int64_t creation_time;
+ int64_t time_base = 1;
if (mkv->mode != MODE_WEBM ||
av_dict_get(s->metadata, "stereo_mode", NULL, 0) ||
@@ -1850,7 +1853,10 @@ static int mkv_write_header(AVFormatContext *s)
return ret;
pb = mkv->info.bc;
- put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, 1000000);
+ time_base = av_rescale_q(time_base, mkv->time_base, (AVRational){1,
1000000000});
+ av_log(s, AV_LOG_DEBUG, "TimestampScale is: %" PRId64 " ns\n", time_base);
+ put_ebml_uint(pb, MATROSKA_ID_TIMECODESCALE, time_base);
+
if ((tag = av_dict_get(s->metadata, "title", NULL, 0)))
put_ebml_string(pb, MATROSKA_ID_TITLE, tag->value);
if (!(s->flags & AVFMT_FLAG_BITEXACT)) {
@@ -1883,11 +1889,11 @@ static int mkv_write_header(AVFormatContext *s)
int64_t metadata_duration = get_metadata_duration(s);
if (s->duration > 0) {
- int64_t scaledDuration = av_rescale(s->duration, 1000,
AV_TIME_BASE);
+ int64_t scaledDuration = av_rescale_q(s->duration, AV_TIME_BASE_Q,
mkv->time_base);
put_ebml_float(pb, MATROSKA_ID_DURATION, scaledDuration);
av_log(s, AV_LOG_DEBUG, "Write early duration from recording time
= %" PRIu64 "\n", scaledDuration);
} else if (metadata_duration > 0) {
- int64_t scaledDuration = av_rescale(metadata_duration, 1000,
AV_TIME_BASE);
+ int64_t scaledDuration = av_rescale_q(metadata_duration,
AV_TIME_BASE_Q, mkv->time_base);
put_ebml_float(pb, MATROSKA_ID_DURATION, scaledDuration);
av_log(s, AV_LOG_DEBUG, "Write early duration from metadata = %"
PRIu64 "\n", scaledDuration);
} else if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
@@ -1948,12 +1954,12 @@ static int mkv_write_header(AVFormatContext *s)
// after 4k and on a keyframe
if (IS_SEEKABLE(pb, mkv)) {
if (mkv->cluster_time_limit < 0)
- mkv->cluster_time_limit = 5000;
+ mkv->cluster_time_limit = av_rescale_q(5000, (AVRational){1,
1000}, mkv->time_base);
if (mkv->cluster_size_limit < 0)
mkv->cluster_size_limit = 5 * 1024 * 1024;
} else {
if (mkv->cluster_time_limit < 0)
- mkv->cluster_time_limit = 1000;
+ mkv->cluster_time_limit = av_rescale_q(1000, (AVRational){1,
1000}, mkv->time_base);
if (mkv->cluster_size_limit < 0)
mkv->cluster_size_limit = 32 * 1024;
}
@@ -2713,6 +2719,14 @@ static int mkv_init(struct AVFormatContext *s)
} else
mkv->mode = MODE_MATROSKAv2;
+ // WebM requires a timestamp precision of 1ms.
+ if (mkv->mode == MODE_WEBM) {
+ if (av_cmp_q(mkv->time_base, (AVRational){1, 1000}) != 0) {
+ av_log(s, AV_LOG_ERROR, "WebM requires 1ms timestamp precision\n");
+ return AVERROR(EINVAL);
+ }
+ }
+
mkv->cur_audio_pkt = av_packet_alloc();
if (!mkv->cur_audio_pkt)
return AVERROR(ENOMEM);
@@ -2738,8 +2752,8 @@ static int mkv_init(struct AVFormatContext *s)
track->uid = mkv_get_uid(mkv->tracks, i, &c);
}
- // ms precision is the de-facto standard timescale for mkv files
- avpriv_set_pts_info(st, 64, 1, 1000);
+ // Use user-defined timescale.
+ avpriv_set_pts_info(st, 64, mkv->time_base.num, mkv->time_base.den);
if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT) {
if (mkv->mode == MODE_WEBM) {
@@ -2759,6 +2773,10 @@ static int mkv_init(struct AVFormatContext *s)
track->track_num_size = ebml_num_size(track->track_num);
}
+ // Scale the configured cluster_time_limit.
+ if (mkv->cluster_time_limit >= 0)
+ mkv->cluster_time_limit = av_rescale_q(mkv->cluster_time_limit,
(AVRational){1, 1000}, mkv->time_base);
+
if (mkv->is_dash && nb_tracks != 1)
return AVERROR(EINVAL);
@@ -2826,6 +2844,7 @@ static const AVOption options[] = {
{ "infer", "For each track type, mark the first track of disposition
default as default; if none exists, mark the first track as default.", 0,
AV_OPT_TYPE_CONST, { .i64 = DEFAULT_MODE_INFER }, 0, 0, FLAGS, "default_mode" },
{ "infer_no_subs", "For each track type, mark the first track of
disposition default as default; for audio and video: if none exists, mark the
first track as default.", 0, AV_OPT_TYPE_CONST, { .i64 =
DEFAULT_MODE_INFER_NO_SUBS }, 0, 0, FLAGS, "default_mode" },
{ "passthrough", "Use the disposition flag as-is", 0, AV_OPT_TYPE_CONST, {
.i64 = DEFAULT_MODE_PASSTHROUGH }, 0, 0, FLAGS, "default_mode" },
+ { "timestamp_precision", "Timestamp precision to use for the entire
container", OFFSET(time_base), AV_OPT_TYPE_RATIONAL, { .dbl = 0.001 },
0.000000001, INT_MAX, FLAGS},
{ NULL },
};
--
2.31.1.windows.1
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