My video has a voice track and a background audio track. 90% of the time it plays correctly, but in specific instances the background music will play but the voice track sounds distorted and you can't hear anything. So far this has come up on a PC laptop when going audio out into a ballroom speaker setup and on the iPhone Youtube app (no voice on speaker but there's voice when using headphones).
Any ideas on what might be causing this and/or potential solutions?
Is it possible there isn't only a stereo audio track in your Quicktime file? If you open it in QT7 and open the Movie Properties (cmd-J), there should ideally only be one Sound Track. When you select it and go to the Audio Settings tab at the bottom, you can see where each channel is assigned, the track's volume, balance and basic EQ. If you have two mono tracks, one with music and the other with VO, and the VO track's settings are out of whack, it could explain your results depending on the player software used in each case.
Extracting the tracks and mixing them to a stereo mix would be your best remedy in that case. If you have a single stereo track, I'd look into audio wiring issues in the system it doesn't work on.
Thanks for the suggestion. I checked the audio settings with QT7 and the audio tracks are set to stereo (Channel 1: Left, Channel 2: Right). The only other thing I wonder is if AAC format might be an issue (thought I don't think it should be.
However, I'm still having VO issues when I play it on the iPhone Youtube App (but not the iPad app). I thought I saw somewhere that this was a known but in the iPhone Youtube App, but can't find any documentation of that anymore.