I have a 4K mkv video file (Dolby Vision, Version 1.0, dvhe.08.06, BL+RPU, HDR10 compatible / SMPTE ST 2086, HDR10) muxed with HE-AAC 8 channels audio, which plays perfectly fine. However, I also have a True Dolby Atmos audio separately (.thd) and I have no idea how to sync that to the MKV file on my Z9X pro instead of playing the 8 channel audio. It won't even detect the file. Any advice will be appreciated
You'll need to mux it into the video file with MKVToolnix. As for whether it will sync or not - that really depends on the source of both files. There is an audio offset up to a maximum of +/-10s assignable from the Up/Down D-Pad using Settings/Playback/Function Keys: If the audio will sync but there is an audio offset, you can determine the value using the above and then bake it into the file by remuxing once again but applying that offset to the audio track in "Timestamps and default duration" in MKVToolnix.
A bit late on reporting on this but it did solve the problem when muxed with MKVtoolnix and I can even switch between 2 audio files now.
Audio offset with up/down keys does not work on my z9x pro (1.0.75_G), nothing happens when i put eg a delay of 3sec........