Up until now, the TrackUID of a Matroska track which is supposed to be
random was not random at all: It always coincided with the TrackNumber
which is usually the 1-based index of the corresponding stream in the
array of AVStreams. This has been changed: It is now set via an AVLFG
if AVFMT_FLAG_BITEXACT is not set. Otherwise it is set like it is set
now (the only change happens if an explicit track number has been
chosen via dash_track_number, because the system used in the normal
situation is now used, too). In particular, no FATE tests need to be
updated.
This also fixes a bug in case the dash_track_number option was used:
In this case the TrackUID was set to the track number, but the tags were
written with a TagTrackUID simply based upon the index, so that the tags
didn't apply to the track they ought to apply to.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
Changed the UID to 64bit and also removed the possibility to call
av_get_random_seed() more than once during init. Furthermore improved
the choice of UID a bit more in case of collisions.
libavformat/matroskaenc.c | 65 ++++++++++++++++++++++++++++++++++-----
1 file changed, 57 insertions(+), 8 deletions(-)
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c
index 1d3203c969..98be7f7a2f 100644
--- a/libavformat/matroskaenc.c
+++ b/libavformat/matroskaenc.c
@@ -94,6 +94,7 @@ typedef struct mkv_cues {
typedef struct mkv_track {
int write_dts;
int has_cue;
+ uint64_t uid;
int sample_rate;
int64_t sample_rate_offset;
int64_t last_timestamp;
@@ -1199,8 +1200,7 @@ static int mkv_write_track(AVFormatContext *s,
MatroskaMuxContext *mkv,
track = start_ebml_master(pb, MATROSKA_ID_TRACKENTRY, 0);
put_ebml_uint (pb, MATROSKA_ID_TRACKNUMBER,
mkv->is_dash ? mkv->dash_track_number : i + 1);
- put_ebml_uint (pb, MATROSKA_ID_TRACKUID,
- mkv->is_dash ? mkv->dash_track_number : i + 1);
+ put_ebml_uint (pb, MATROSKA_ID_TRACKUID, mkv->tracks[i].uid);
put_ebml_uint (pb, MATROSKA_ID_TRACKFLAGLACING , 0); // no lacing (yet)
if ((tag = av_dict_get(st->metadata, "title", NULL, 0)))
@@ -1651,7 +1651,8 @@ static int mkv_write_tags(AVFormatContext *s)
if (!mkv_check_tag(st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID))
continue;
- ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID,
i + 1);
+ ret = mkv_write_tag(s, st->metadata, MATROSKA_ID_TAGTARGETS_TRACKUID,
+ mkv->tracks[i].uid);
if (ret < 0) return ret;
}
@@ -1659,13 +1660,15 @@ static int mkv_write_tags(AVFormatContext *s)
for (i = 0; i < s->nb_streams; i++) {
AVIOContext *pb;
AVStream *st = s->streams[i];
+ mkv_track *track = &mkv->tracks[i];
ebml_master tag_target;
ebml_master tag;
if (st->codecpar->codec_type == AVMEDIA_TYPE_ATTACHMENT)
continue;
- mkv_write_tag_targets(s, MATROSKA_ID_TAGTARGETS_TRACKUID, i + 1,
&tag_target);
+ mkv_write_tag_targets(s, MATROSKA_ID_TAGTARGETS_TRACKUID,
+ track->uid, &tag_target);
pb = mkv->tags_bc;
tag = start_ebml_master(pb, MATROSKA_ID_SIMPLETAG, 0);
@@ -1865,10 +1868,6 @@ static int mkv_write_header(AVFormatContext *s)
version = 4;
}
- mkv->tracks = av_mallocz_array(s->nb_streams, sizeof(*mkv->tracks));
- if (!mkv->tracks) {
- return AVERROR(ENOMEM);
- }
ebml_header = start_ebml_master(pb, EBML_ID_HEADER, MAX_EBML_HEADER_SIZE);
put_ebml_uint (pb, EBML_ID_EBMLVERSION , 1);
put_ebml_uint (pb, EBML_ID_EBMLREADVERSION , 1);
@@ -2670,8 +2669,42 @@ static int webm_query_codec(enum AVCodecID codec_id, int
std_compliance)
return 0;
}
+static uint64_t mkv_get_uid(const mkv_track *tracks, int i, AVLFG *c)
+{
+ uint64_t uid;
+
+ for (int j = 0, k; j < 5; j++) {
+ uid = (uint64_t)av_lfg_get(c) << 32;
+ uid |= av_lfg_get(c);
+ if (!uid)
+ continue;
+ for (k = 0; k < i; k++) {
+ if (tracks[k].uid == uid)
+ break;
+ }
+ if (k == i)
+ return uid;
+ }
+
+ /* Make the uid odd so that it is invertible mod 2^n.
+ * This implies that the multiples of uid below are all distinct. */
+ uid |= 1;
+ for (int j = 1, k; j < i + 1; j++) {
+ for (k = 0; k < i; k++) {
+ if (tracks[k].uid == j * uid)
+ break;
+ }
+ if (k == i)
+ return j * uid;
+ }
+ /* Return (i + 1) * uid. It can't coincide with another uid. */
+ return (i + 1) * uid;
+}
+
static int mkv_init(struct AVFormatContext *s)
{
+ MatroskaMuxContext *mkv = s->priv_data;
+ AVLFG c;
int i;
if (s->nb_streams > MAX_TRACKS) {
@@ -2700,7 +2733,23 @@ static int mkv_init(struct AVFormatContext *s)
s->internal->avoid_negative_ts_use_pts = 1;
}
+ mkv->tracks = av_mallocz_array(s->nb_streams, sizeof(*mkv->tracks));
+ if (!mkv->tracks) {
+ return AVERROR(ENOMEM);
+ }
+
+ if (!(s->flags & AVFMT_FLAG_BITEXACT))
+ av_lfg_init(&c, av_get_random_seed());
+
for (i = 0; i < s->nb_streams; i++) {
+ mkv_track *track = &mkv->tracks[i];
+
+ if (s->flags & AVFMT_FLAG_BITEXACT) {
+ track->uid = i + 1;
+ } else {
+ track->uid = mkv_get_uid(mkv->tracks, i, &c);
+ }
+
// ms precision is the de-facto standard timescale for mkv files
avpriv_set_pts_info(s->streams[i], 64, 1, 1000);
}
--
2.20.1
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