I've been trying to re-encode some x265 to x264. MKV to MKV container. I've chosen "copy" for audio output. But the DTS-HD MA (8 channel) track doesn't get preserved. I'm ending up with what I assume is DTS Core (only 6 channels).
I thought it was supposed to copy the audio track as is?
(I couldn't figure it out so downloaded and installed Handbrake and that has worked for me.)
Confirmed that only core is detected, will try to investigate later, thank you.
Indeed, it turns out, Avidemux supports DTS core only, skips the DTS-HD part of each audio packet. I'll try to look into it properly during the next release cycle.
Both copy mode and playback (up to 8 channels) for DTS-HD MA should work now. Please try a build off the current git master / a future nightly.