| Message ID | 20191203151947.24685-1-andreas.rheinhardt@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
On Tue, Dec 03, 2019 at 04:19:47PM +0100, Andreas Rheinhardt wrote: > 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. LGTM thx > > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> > --- > I have updated the patchset to rely on the AVLFG to provide sufficiently > many distinct values, as you said. I could add a check and a for if we still > have a collision after (say) 1000 tries in order to avoid the > potentially infinite loop. You could replace the LFG if you dont trust it. But i dont understand why you would use it when you dont trust it and then add a check Thanks [...]
Michael Niedermayer: > On Tue, Dec 03, 2019 at 04:19:47PM +0100, Andreas Rheinhardt wrote: >> 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. > > LGTM > thx > Good to hear. When merging, the fix for ChapterUIDs (https://ffmpeg.org/pipermail/ffmpeg-devel/2019-November/253440.html) should get merged first. > >> >> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> >> --- >> I have updated the patchset to rely on the AVLFG to provide sufficiently >> many distinct values, as you said. I could add a check and a for if we still >> have a collision after (say) 1000 tries in order to avoid the >> potentially infinite loop. > > You could replace the LFG if you dont trust it. > But i dont understand why you would use it when you dont trust it and then > add a check > I actually trust that it works; it's just that I can't furnish a proof. - Andreas
diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c index 41c3f1a985..b2f28304c8 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 +2669,29 @@ 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; + + while (1) { + int k; + 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; + } +} + static int mkv_init(struct AVFormatContext *s) { + MatroskaMuxContext *mkv = s->priv_data; + AVLFG c; int i; if (s->nb_streams > MAX_TRACKS) { @@ -2700,7 +2720,23 @@ 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); }
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.rheinhardt@gmail.com> --- I have updated the patchset to rely on the AVLFG to provide sufficiently many distinct values, as you said. I could add a check and a for if we still have a collision after (say) 1000 tries in order to avoid the potentially infinite loop. libavformat/matroskaenc.c | 52 +++++++++++++++++++++++++++++++++------ 1 file changed, 44 insertions(+), 8 deletions(-)