This year for Good Friday, we need to run some video. But not just any video; it needs to have two tracks of synth/pad and music stuff, a sound effects track and a click track. And each track needs to be discreet so we can mix it with the live music (not to mention send the click to just the musicians). I was pretty sure that QuickTime could handle multi-track audio; I just wasn’t sure how I was going to do it. I spent the better part of a day figuring it out (with the help of the Twitter-verse), so I thought I’d share the process, if only so I don’t forget how! First up, we need to spend some quality time in FinalCut Pro (you could probably do this in Premier, Vegas and just about any other NLE, but I don’t have any of them–so I can’t help there).
The first step is to set up the sequence properly. In our case, we had the need for 4 audio tracks. The default sequence has 4, so we’re good. However, by default, FCP is set to mix down all tracks to stereo, and that won’t work for us. Make a trip to Sequence -> Settings… and select the Audio Outputs tab. Change the Outputs from 2 to 4, then select Dual Mono. The Downmix (dB) setting will switch to -3, change it back to 0. Click OK. You will probably get a warning that your output device does not support 4 tracks (unless you have a multi-track output device attached). Ignore the warning, and don’t tell it to downmix.
Next, go to each track and right click over on the left side somewhere next to the green channel on indicator. Select the correct audio output channel for each track. I kept our simple and mapped them 1:1. Stereo tracks on 1&2, FX on 3 and Click on 4. Even though my tracks were stereo, I told FCP to make it dual mono. It may actually work in stereo mode, but I was having trouble with QuickTime downmixing so I changed it. Your mileage may vary.
Now that you have your sequence set up, you need to export. If I had my druthers, I would export using Compressor. However, we have an old version of FCP that is not 100% compatible with our updated OS, so Compressor doesn’t work. So the only way I was able to export properly was to Export as QuickTime Movie. I left all the settings just as they were and clicked OK. It’s important to leave “Make Movie Self-Contained” checked. I wouldn’t recompress all frames. Save your file and you’re all set.
At this point, you should have a QuickTime movie with 4 tracks. However, if you try to play it, it will downmix the tracks to stereo. This is what took me all day to figure out. The trick is to adjust the audio tracks in QuickTime 7 Pro. I believe Apple removed these features from QuickTime X, so you’ll still need to keep 7 Pro around. Here’s the scoop.
Click on Sound Track 1 and from the Channel | Assignment menu, select Discrete-0 (make sure you start at 0, not 1). Set Track 2 to Discrete-1 and so on. That will tell QuickTime to send each track out to a multi-track output device as a separate, discrete track. Save the movie (it will take but a second, as you are just modifying a parameter).
Now look at your Inspector again; it should show each track as a Discrete output. When you get to your playback computer, you need to make sure your USB or FireWire audio interface is selected for output. You can do that from the Sound System Preferences, or from Audio MIDI Setup.
In Audio MIDI Setup, control-click on your output device and select “Use this device for sound output.” I highly recommend you use the Built-in Output for system sounds–that way you won’t get any beeps or other system sound effects through the house PA.
That’s it. I tested my newly multi-tracked movie in Keynote, ProPresenter and QuickTime player. Every one played all four tracks perfectly through my brand-spaking new M-Audio Fast Track Ultra. Happy multi-tracking!