I'm a sound editor by trade and not super versed in FCP or FCPX, so apologies if this is a little rough:
I have a Prores QT file with 5.1 + 2 soundtracks already exported and done (from a client). I also have a production company logo and 8 channels of audio (5.1 + 2) I need to amend to the head of the client file and re-export.
Imported my video logo file into timeline, no problem.
I pulled in the 8 audio files related to that logo.
I assigned channel configuration to each of the 8 files.
I created a 2-0 mix role and a 5-1 mix role and assigned each file to the correct role.
I pulled them into the timeline in sync with the logo
I then imported the client file into the sequence and dropped it into the timeline
I expanded the audio to see all 8 tracks are present
Under configuration for that file I chose 5.1 + 2 and the audio channels view in the timeline updates and shows 1 surround channel and one stereo channel. It doesn't give me options for selecting individual channels and assigning them, but this still seemed to be correct,
I assigned each to the appropriate ROLE (5-1 and 2-0 respectively)
Finally I go to SHARE Master File
I make it a multitrack quicktime with the 5-1 role and the 2-0 role
and I export.
It creates a quicktime file which at first glance LOOKS correct, the INFO browser shows 5.1 and Matrix Stereo however if I pull it into any software to verify the channels are in the right order it reveals that the 5.1 tracks just have audio on 1/2 and channels 3-6 are blank.
It seems to be creating a "downmix" of the surround audio when exporting the 5-1 role, although it's still creating all 8 tracks in the QT container file. It s doing so for both the client file audio AND for the logo audio I added: so no matter if it is 6 individual files with assigned channel configurations OR if it is a 'Surround' track puled in an already wrapped QT.
Is there a setting somewhere I'm missing in terms of letting FCPX export discrete channels without downmixing them? Any help would be greatly appreciated!