Resolving Problems with Multi-channel Audio in Soundtrack Pro
[ This article was first published in the January, 2009, issue of
Larry's Final Cut Pro Newsletter. Click here to subscribe. ]
I ran into an interesting problem with Soundtrack Pro recently… Well, it’s “interesting” now that I’ve solved it, but for two weeks it was driving me NUTS! Anyway, along the way I discovered new features in Soundtrack that I hadn’t worked with before, so I wanted to share them with you.
Here’s the problem: when I mix my audio in Soundtrack Pro, I can hear all the tracks. When I export the final mix, all my voice-over audio disappears. Very, very weird. And recent, as this has worked reliably in the past.
I do a lot of screen-capture recording for all my different tutorials. The utility I use to capture them (SnapZPro) always records four channels of audio:
Channel 1: Left channel, Mac audio
Channel 2: Right channel, Mac audio
Channel 3: My voice from a microphone
Channel 4: Blank
If I were to open the audio file in Soundtrack Pro it would look like this. Notice that my audio is on track 3 and tracks 1 and 2 are blank.
My general workflow for these tutorials is to open these files in Final Cut and edit them until I’m happy with how the images look. Then, I send the files (File > Send to > Soundtrack Pro Multitrack Project) to Soundtrack for mixing and final sweetening.
So far, so good.
I then go through the process of cleaning up breaths, smoothing out transitions, and applying filters until things sound the way I want. During all of this, I’m monitoring everything through my studio speakers.
Again, no problems.
Finally, its time for output. To bring a mix back to Final Cut Pro, you export it (File > Export).
Now things get weird. The audio meters bounce for the music at the open, then totally die for the rest of the export. Nothing. Zip. Silence.
Needless to say, I found this somewhat, ah, discouraging.
The first thing I did was check out Apple’s KnowledgeBase, which did not have anything about this.
Then, I wondered if the problem was in how I was sending the file from Final Cut. So I tried using two different versions of Final Cut Pro 6 and two different versions of QuickTime. Same problem.
Finally, after about two weeks, I figured out what was causing the problem, which lead me to the workarounds I want to share with you today.
Look again at the audio on the track labeled “Larry.” Notice that while STP thinks it is a mono file (only one waveform is displayed), as we saw earlier the file is actually four tracks. Because of this, during export, Soundtrack only exports the first track, which is silent, rather than the third track, which is what it is displaying in the Timeline. From my point of view, this is a bug.
There are two ways to solve this: before you start the edit and after the edit is complete.
THE BEFORE-THE-EDIT SOLUTION
One of the least-known features in Soundtrack is the ability to change track order, then save that revised track order back into the source file. This is done using the Process menu.
Since STP was expecting my voice on track 1, what I needed to do was to move my voice over from track 3 to track 1. To do this, I opened the clip as a Soundtrack Audio Project, then selected Process > Reorder Channels.
Because I wanted track 3 to be the first track, I dragged it to the top of list. Then, because both FCP and STP want stereo pairs to start on an odd-numbered track, I dragged track 4 up under track 3.
This reordered my tracks from 1 – 2 – 3 – 4 to 3 – 4 – 1 – 2. The key is to make sure my voice track was the first one in the clip.
It takes a while for STP to process the file and a while longer to save it back to the hard disk. On the other hand, this reliably solves the problem for the entire file, prior to starting the edit.
THE AFTER-THE-EDIT SOLUTION
However, if the edit is complete and you have this problem, changing the source file won’t make your life any easier. In which case, here’s the workaround.
Send the file from FCP to STP as a multi-track project.
Then, Control+click in the first audio segment that is refusing to export properly and change the channel selection from its default of 1 to the channel your voice over (or other audio) is on.
Note: You may need to double-click one of these files in order to see what tracks your audio is actually stored in.
The only problem with this approach is that you need to reset each individual misbehaving segment manually. However, once you have the channels pointing in the right direction, you’ll be able to export with no problems.
I’m sure that Apple will fix this problem in future versions of the software. For now, though, this was a great way for me to discover features in Soundtrack that I never knew it had.
And the nice thing is that once I made these changes to my files, the whole mixing process worked flawlessly.