I have to deliver a film. We submit to Bitmax and their specs for audio are below.
Audio thats required:
7+8- Stereo Pair
I've done a bit of research and figured out the audio mapping, and gotten to 8 channels once I export, but with the 4th channel the LFE track it copies the 3rd channel. I've tried a few different things, but I always get the LFE track copying the other track. All the other channels do not have this problem.
This is assuming you already have your video exported as a single clip and just want to repurpose it to iTunes spec.
I find the easiest way to work with audio is to mimic an FCP type of setup;
1. Make a timeline with a multi-channel master track and set it to have 8 channels. Obviously make sure the video settings match up with your source.
2. Add 8 adaptive tracks.
3. Use the mapping option to map track 1, input 1 to output 1. Map track 2, input 1 to output 2. Map track 3, input 1 to output 3 and so on. Make sure you set you set inputs 2-8 to none.]
4. On your clip, modify the audio channels and set the preset to Mono, Number of Audio Tracks to 8 and Channel Format to Mono. Make sure the Source and Channel mapping maps Source Channel 1-8 to Tracks 1-8.
5. Drop the clip onto your timeline and you'll be good to go. When you do your export, in the Export Settings, set the Basic Audio Settings to 8 channel, Track Layout to 8 Mono Pairs and Channel Layout can be left on Mono (make sure you change the channel assignments in QuickTime Pro once exported).