When remuxing mkv into m4v with eac3 6(+) sound track, subler creates non 0 offset

[Vasily]

When working with an mkv file containing either eac3 6 channel track or eac3 + atmos, resulting m4v file ends up with non zero offset. This can be verified by selecting the audio track of the finished m4v and selecting offset from edit menu, the window is normally filled with a number 191.999. This obviously creates a slight audio sync issue. Temporary solution is to put a zero in offset field box and save the file again.

[Damiano Galassi]

Is the offset in the eac3 track or in the converted aac? The offset in the AAC is required, because it's the priming delay (see https://developer.apple.com/library/archive/documentation/QuickTime/QTFF/QTFFAppenG/QTFFAppenG.html ). But maybe the app you use to play the file is buggy and applies a a double delay. Or there was a delay in the audio track in the mkv too.

But I am not a wizard and I can't guess everything.

[Vasily]

The offset is in the eac3 track, no conversion is done. Straight passthrough of h264 or hevc video track plus eac3 6 channel sound track adds offset on eac3 track. Rhe offset is roughly 190ms. Happens with every file, delay is noticeable in any app. To confirm the issue all you have to do is open the converted m4v file in subler and look at the offset on eac3 track.

[Damiano Galassi]

Right, the code that analyses atmos tracks didn't reset the seek point in mkv. Try https://subler.org/downloads/Subler-Test.zip

[Damiano Galassi]

Issue #493 was marked as a duplicate of this issue.

[Damiano Galassi]

Fixed in 1.5.9.