Changing default MKV audio track (Game of Thrones + Atmos)

[Giffdev]

Hey folks, I've been getting into the video back-up world lately and recently backed up all of my Game of Thrones UHD disks to play on Plex. However, what bothers me from both the disks and the mkv rips is how the 5.1 audio is default, rather than Dolby Atmos audio.

Can someone point me to a tutorial (or teach me if you're extra nice) how I can edit the MKV file to swap this? I am not trying to add any compression to the files or muck around with the MKV file any more than swapping the audio defaults. I heard there was a tool named MKVToolNix and I can open the file in there and see the audio tracks, with 5.1 listed as the default, but I don't know how to "edit" these. Nor do I know if editing them and resaving will cause any degredation in video quality, etc. as I want to keep things to as much of an uncompressed backup of the disk as possible, with this little tweak.

Thanks in advance!

[d00zah]

Use the MKVToolNix Header Editor. Just select the desired element, set the default flag & 'save' from the 'Header editor' pull-down.

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[Giffdev]

Thanks D00zah, that's straightforward. Do you know if I need to refresh meta data or scan files again in Plex to pick up the changes, or will it just do that at runtime when I go to play the video files after editing?

[d00zah]

I'm an Emby guy, but a rescan seems reasonable to update metadata displayed. If Plex is anything like Emby, a quick scan is performed for any playback request to evaluate whether transcoding is required, so I expect it would look at flags? Try playing the updated file & see. Pretty simple experiment, no?

[Giffdev]

Yep, just stuck at the work desk right now but I'll try on my nvidia shield plex setup this evening

[Giffdev]

For anyone who reads this and cares later, setting the default flag on audio didn't seem to change anything as far as plex was concerned, at least for Game of Thrones. It DID however care that for GOT subtitles I set them to forced.

Instead, I'm using MKVToolNix to just remove the 5.1 audio track, which then allows Plex to default to the 7.1 file if you run the "Analyze" command. Very time consuming, but at least I'm paying it forward to anyone on my plex server who tries to watch it in the future.