Some MKV from Dolby Vision ISOs are incorrectly created with MakeMkv

[raptor17]

Hi everyone.

Until now I've been using the old way to convert m2ts backup files with 2 tracks to mp4 in order be usable in my LG TV (directly from m2ts files to mp4 profile 7) with no issues. Last weeks I've been trying with muxed mkv's created with MakeMkv from ISO files. Just demuxing the video file in BL + EL from the mkv to build mp4 files from those.

Some work (Hobbit, Spartacus) and some don't (Gladiator, Mission Imposible) so I've done a test with one of my favourite that doesn't work from mkv but it works from m2ts: Gladiator.

If you extract the video tracks from the m2ts you get this:

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-rw-rw-r-- 1 mediahouse mediahouse 55534597226 feb 11 11:56  BLfromISO.hevc
-rw-rw-r-- 1 mediahouse mediahouse  8750115761 feb 11 11:56  ELfromISO.hevc

And you can build a fully working DoVi mp4 file from those (adding the sound track). But if you create a mkv file using MakeMkv 1.5.3 or 1.5.4, and you demux with yusesope or quietvoid tool, you get the first two files from the full one (the last):

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-rw-rw-r-- 1 mediahouse mediahouse 55547338813 feb 11 14:23  BLfromMKV.hevc
-rw-rw-r-- 1 mediahouse mediahouse  2605405031 feb 11 14:23  ELfromMKV.hevc
-rw-rw-r-- 1 mediahouse mediahouse 58154237092 feb 11 10:13  FULLvideotrackfromMKV.hevc

The ELfromMKV track is just too short. Checking the process while it's demuxing the mkv source, after a few minutes, the EL file just get "stuck" in that size while the BL ones grows to their final size., I mean the demuxer just doesn't find more EL frames in the full video hevc source after certain point.

If you compare the size of both BL files (from the m2ts and from the video inside mkv) they are basically equal. So the BL is the roughly the same. And the full EL track from the m2ts is 8Gb+ while the version from Mkv is 2.5Gb+.


So I went a step back and I ripped again the mkv from the ISO with MakeMKV. When generating the mkv file, MakeMkv reports a serious a mount of sync issues, and after a few minutes it seems it tries to resyncrhonize withouth luck, but it finishes generating a mkv file which works well in HDR10. So I don't think the problem is in the demuxer but in the way MakeMkv deals with certatin m2ts files trying to synchronize the 2 video tracks to mux them into one track.

So my basic conclussion is that MakeMkv, under certain circumstances (I guess sync issues detected while ripping), fails to build a correct/complete video track with all DoVi needed info from both source tracks. Those MKV files may trigger DoVi at the begining on certain players (Shield...), but after a bunch of minutes no DoVi info seems to be there.

Titles with no issues: Hobbit, Spartacus,...
Titles with issues: Mission Impossible, Gladiator,..

Hence I'm afraid some mkv created from ISO aren't complete, so no way to recover full DoVi info from those.

Thanks in advance (and forgive my limited english)

¿ Anyone more experiencing issues related to this ?

[raptor17]

I still hope I could get an answer about this issue.

Right now I can't fully trust in mkv's as safe replacements of Dolby Vision UHD backups. It seems the safest way to keep a reliable backup of those disks is still a full ISO image of them.

¿ Anyone more could please take a look into this ?

Thanks !

[staknhalo]

Hey, can you shoot me a PM what titles you've found with this error? I've been backing up to mkv from folder backups of physical discs I made - wondering if any of these errors occur on a per title basis - or just general/random sync errors occurring whenever it happens.

Edit: I'm assuming more than the 4 there

[raptor17]

Sorry, my account is too new an I still can't send private messages.

I've found at least 5 movies with that issue, and about 10 without problems demuxing BL and EL from the joined hevc mkv video track. The process is a bit slow so I stopped by now investigating the issue just by myself, that's why I opened this thread. Just trying to expose the problem so developers could find a way to solve it.

[joaopedro000]

I don't know if it has a connection, but my TV doesn't recognize Dolby Vision in some files created with MakeMKV. Until today I had think it was a compatibility problem of my TV, but this is a issue that deserves a investigation.

[raptor17]

I want to add this log of non-working title while ripping with MakeMkv

Most errors arise in most titles at between 45 and 50. I'm starting to think it could be due to some kind of precision error. I'm running it in Ubuntu 20.04.

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AV sync issue in stream 0 at 0:47:50.576 : secondary stream video frame timecode differs by +83.322ms
AV sync issue in stream 0 at 0:47:50.742 : secondary stream video frame timecode differs by -0.1ms
AV sync issue in stream 0 at 0:47:50.742 : secondary stream video frame timecode differs by +125.033ms
AV sync issue in stream 0 at 0:47:50.909 : secondary stream video frame timecode differs by -0.1ms
AV sync issue in stream 0 at 0:47:50.909 : secondary stream video frame timecode differs by +83.322ms
AV sync issue in stream 0 at 0:47:50.909 : too many video frames with invalid timecodes, future messages will be suppressed

¿ Could be possible in the next release to add an option to ignore those invalid time codes or to try to fix them ?

Just waiting for some answer


Thanks anyway.

[dcoke22]

I've never made an ISO of movie… How do you make them? And then how do you make .mkv files from them?

[raptor17]

ISO is a file container, a format to keep a perfect copy of an optical media. It's just a file structure inside a file (the ISO file),

There are plenty of tools to make an ISO. The ISO structure for movies to be playable in BD or UHD players is well known and a open standard.

Take a look to authoring tools.

MakeMkv is able to read a ISO file with one of the admitted file schemes (DVD, BD, UHD...) and parses its content and can just copy the content (but also decrypt it while copying).

The opposite can also be done.

[dcoke22]

More specifically, what tools do you use and why? In my own journey to get bits off discs sitting on my self and into a Plex server, I've never had a need to make an ISO. Do you have a professional workflow that uses ISOs? Do you have an archive of previously made ISOs that you are now trying to move into a MKV container? Something else?

In your original post, you mentioned sometimes there are AV sync issues when creating .mkvs from an ISO. For the movies you have found to be problematic, do you have the discs handy and could you make a MKV directly from the disc, without the ISO step in the middle? I'm curious if MakeMKV handles the AV sync issues differently… presumably it is those errors that are confusing the demuxer resulting in a smaller enhancement layer.

[raptor17]

Some users like to have an ISO to be played with Oppo like machines. Even some TV Boxes can play full-menu BDR.

Obviously not compatible with PLEX.

DVDFab (https://www.videohelp.com/software/sect ... -bd-hd-dvd) is a pretty popular tool.

And the issue is related while MakeMKV is reading both videotracks (Basic Layer + Enhanced Layer) from the same m2ts file.