Seamless Branching Disk Remux by MKVToolnix

[chansavat]

Some time ago MakeMKV had problem with Atmos disk that have seamless branching (different version of movies on one disk).

For branching disk during that time ... I used MakeMKV to rip into folder structure to remove encryption ... and used MKVToolnix to make MKV, as at the time it handled branching better.

I know MakeMKV drops audio frames or add silence at branching point to minimize sync between audio and video within one audio frame.

Not sure how MKVToolnix handles this ... dont think it drops any audio or video frames ... read somewhere (don't remember where) that it marks video as variable frame rate at the joint to sync audio and video. This seems to be true as MKVToolnix MKV are longer than MakeMKV MKV by approximately number of frames that MakeMKV drops.

In some cases ... what MKVToolnix does result in slight "clicks" in audio at the joints, while revised MakeMKV seems to work better now.

And here comes my problem. If I run MakeMKV on files generated by MKVToolnix, as expected MakeMKV finds sync issues but does not attempt to sync them. All variable frame rates seems to be removed ... and resulting MKV is out of sync.

I can rerip discs using MakeMKV but ripping from discs is such a time consuming process. Is it possible for MakeMKV (if explicitely specified that input MKV is from MKVToolnix), to detect "joint" point from branching in MKV and apply its sync algorithm there?

PS. forgive my ignorance if anything I described above is technically incorrect

[chansavat]

What is also interesting ... MakeMKV 1.16.7 sync is not consistent

Here are messages of ripping same playlist with only one audio stream selected (disk is UHD Zootopia which has lots of branching points ... audio selected is Atmos).

The source is a folder structure rip from UHD disc stripped of encryption. So these discrepancies could not come from optical drive. Some case - overlap detected, others no overlap detected. Some cases 2 frames dropped, some cases 3 frames dropped.

I cannot understand these sync discrepancies since it is ripped from same source.

Saving 1 titles into directory G:/Video/Zootopia
AV synchronization issues were found in file 'G:/Video/Zootopia/Zootopia_t02.mkv' (title #3)
AV sync issue in stream 1 at 0:05:44.968 with duration of 0.819ms : encountered overlapping frame, audio skew is +1.652ms
AV sync issue in stream 1 at 1:13:39.038 with duration of 0.833ms : encountered overlapping frame, audio skew is +1.652ms
AV sync issue in stream 1 at 1:13:39.040 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to +0.819ms
AV sync issue in stream 1 at 1:33:13.254 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to +0ms
1 titles saved
Saving 1 titles into directory G:/Video/Zootopia
AV synchronization issues were found in file 'G:/Video/Zootopia/Zootopia_t02.mkv' (title #3)
AV sync issue in stream 1 at 0:05:44.968 with duration of 0.819ms : encountered overlapping frame, audio skew is +1.652ms
AV sync issue in stream 1 at 1:13:39.038 with duration of 0.833ms : encountered overlapping frame, audio skew is +1.652ms
AV sync issue in stream 1 at 1:13:39.040 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to +0.819ms
AV sync issue in stream 1 at 1:22:10.174 with duration of 0.816ms : encountered overlapping frame, audio skew is +1.65ms
AV sync issue in stream 1 at 1:33:13.253 with duration of 0.852ms : encountered overlapping frame, audio skew is +1.666ms
AV sync issue in stream 1 at 1:33:13.255 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to +0.833ms
AV sync issue in stream 1 at 1:34:00.884 with duration of 0.816ms : encountered overlapping frame, audio skew is +1.65ms
AV sync issue in stream 1 at 1:34:00.885 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to +0.816ms
1 titles saved
Saving 1 titles into directory G:/Video/Zootopia
AV synchronization issues were found in file 'G:/Video/Zootopia/Zootopia_t02.mkv' (title #3)
AV sync issue in stream 1 at 1:13:39.039 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to -0.013ms
AV sync issue in stream 1 at 1:33:13.253 with duration of 0.833ms : 1 frame(s) dropped to reduce audio skew to -0.833ms
1 titles saved