Preparing the files
As Chris noted, Call Recorder files are actually QuickTime movies with two separate tracks: your audio and the Skype audio. The utility comes with a small app called Split Movie tracks, which splits that file in two. Once I’ve got all my guests’ audio files in hand, I’ll split out their vocal tracks and drag them all into GarageBand, along with my vocal track and my Skype track. Since my vocal track and my Skype track are already synced (because they were part of the same Call Recorder file), I make sure they’re both lined up at the very beginning of the GarageBand file.
Then I need to get all the tracks in sync. If we all started our recordings at roughly the same time, syncing isn’t too difficult, but it takes some concentration. I turn on GarageBand’s track soloing feature (the headphones icon right below the track name) for my Skype track and one of my guest’s solo tracks, and start playing the audio. It should become clear just how out of sync the tracks are (the same voice says “Recording” twice, but one is a few seconds after the other.) I drag the soloed vocal track around until it syncs up, with little or no echo. (If I get really desperate, I will go back to the Finder and open that person’s Call Recorder file in QuickTime Player: then I can hear the context of what everyone else was saying when they started recording, which can provide a clue as to when their recording actually starts.)
Once a track is synced, I turn off the soloing on that track and turn it on for the next track, and repeat the procedure until all the tracks are synced. At this point I can usually turn off all soloing and delete the Skype track I used for sync purposes. Though sometimes there are disasters which will require the use of the Skype track later on: If someone forgot to record their end of the conversation, or came in late, for example. To be on the safe side, mute the Skype track but keep it around and make sure it stays in sync with all your other tracks, splitting and moving it with the other tracks as necessary.
Filtering out noise
(Image Caption: Using SoundSoap in GarageBand.) The room where I record most of my podcasts at home is pretty quiet, but not everyone is so fortunate. When you pile four or five audio tracks on top of one another, there can be a lot of noise. There’s the faint hiss of room noise, the occasional electronic hum, the sound of the other panelists coming through one participant’s noisy earbuds, and soft but audible noises like breathing (those headsets again!) and typing.
To start off, set your vocal tracks to use GarageBand's No Effects preset, or (if you prefer) the Male or Female Narrator presets. Any of the singing presets will make you sound like you recorded your podcast in a tank of water.
If you care about getting rid of noise, I highly recommend BIAS’s $129 SoundSoap 2. To use SoundSoap, you click on a track in GarageBand and click on the i icon in the lower-right corner, then click Edit. This displays the effects area of GarageBand. Move your cursor over one of those empty gray rectangles and you’ll see the text, “Click here to add an effect.” Click and choose SoundSoap. Then Click on the SoundSoap icon, and you’ll see the SoundSoap interface.
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