PS: I found this solution suggestion but, surprisingly, my computer does not have that preference file to delete:
I've never expereinced this in the three versions of Garageband I have used.
Try refreshing all your preferences for Garageband (GB). Not just one of them...
Go to: ~/Library/Preferences/
Move these files to the desktop - This keeps a quick backup of them. Garageband will re-create these prefs when you re-launch Garageband.
You might have to reset some of your preferences in GB.
If something unwanted happens, just replace your prefs listed above with your desktop copies.
Check what your Audio MIDI Setup is doing also (in Applications/Utilities). Make sure you "input" and "output" is in the same sampling format (e.g. 44.1 KHz, 16 bit) as what GB is doing. GB's preferences say the choice of "Better" is recording at 24 bit, but exporting at 16 bit. Differences in sampling rates between the mac hardware/GB might be causing this.
Try the same preferences move to desktop trick (as above) on Audio MIDI Setup's "com.apple.audio.AudioMIDISetup.plist" (in ~/Library/Preferences also).
What version Garageband are you running? I just noticed in your signature in the OP, you list Garageband '09. Got the latest updates from Software Update?
Try these possible fixes anyway...
- Try a "Save As..." of the problematic project in GB '09 and use the new saved project. Quit, relaunch GB. Does the issue re-present itself?
- Do you start with a new project each time you begin a Podcast?
- Are you dropping jingles and other samples from other files (e.g. MP3, M4A etc) into GB? (i.e. not from the loops browser)
Perhaps get the paid update to Garageband '11 6.0.5 (428.5), then try a new project, or do the "Save As..." suggestion below.
- Update to GB '11 and "File > Save As..." your previous GB '09 project (essentially you will be saving a GB '09 file as a GB '11 project). You can't open a GB '11 project in GB '09 however.
I edit and export to MP3 a lot of spoken content each week (up to 45 minutes in one block) on GB '11 (just because GB is quick, simple and cheap!). I do NR and hard edits in Audacity, export to AIFF and drap-n-drop 44.1kHz, 16bit AIFFs into GB. Maybe it is imported content which wrecks the sampling rate within GB somehow and makes the waveform lose sync... Yes, in that case it could be a bug in the resampling subroutines of GB '09.
Best bet: update.
Thanks for the detailed suggestions - we are running Garage Band '09 and I'll check on having the latest updates (have to do that via IT). I'll also check on if could update to the '11 version.
Unfortunately, "saving as..." does not fix the problem.
They were only working on one podcast/project each so starting a new one isn't a factor
We did drop the original audio files (interviews) into GB as MP3 files but the other things added (jingles, etc.) all came from the Loops browser. It's been hard to recreate the problem (and impossible to undo) but one student did think it started once they'd added items from the loops browser but I'm not 100% convinced we can be certain their memory's correct.
Thanks again for the tips.
My pleasure. I realized you were in an environment that required IT interaction. Hope that does not cause pain.
There are a handful great updated features included in GB '11 and I trust the update would sort out the issue you have been experiencing.
Post back if you get it cleared up. I love to hear happy endings!
All the best.