I worked with two 2nd tier Apple techs who were both very good last thursday. Steven Brown in Final Cut Pro and Roger Johnson from iphone support. We had the problem of the iphone playing back a demos music but unable to process the dialogue my client wanted to hear also.
What we found was that a stereo mix down with two tracks of voice cancelled each other out in the itunes mixdown. Usually two tracks of audio is preferred. We found that if you take the one channel of voice over with music it plays fine through the speaker on the iphone.
The same is true if you post a youtube video and then try and play it thru iphone also. You need to mix it down as a mono Aiff file then reimport it into your timeline. For FCP editors here are the steps.
Here are the steps for exporting a mono audio file from stereo DV audio in Final Cut Pro.
1. Mute all audio tracks in the timeline except the tracks with the DV audio
2. Select the sequence in the Browser
3. Go to File/Export/Using QuickTime Conversion…
4. In the Save dialog change the “Format:” to AIFF and leave the “Use:” at Default
5. Click Options and confirm that the audio is 48 kHz Stereo Linear PCM in the Sound Settings dialog and click OK
6. Save the file with desired name in your desired location
7. Import the mono AIFF file into your project
8. Mute the DV audio tracks
9. Place the mono AIFF on a new audio track
10. It will now play out of left and right channels with the stereo music track and will sum to mono w/out phase cancellation.
Hope this helps others down the road. Thanks again Steven and Roger at apple.
I recently shot and produced a demo for a Professional Seminar speaker and then made him DVD copies etc. I also sent him an iphone version directly from Final Cut pro the editing software I use in all post production. Funny thing is the music played all the way through but his voice was lost after it was synced to the iphone from itunes. You can hear the music thru the little speaker but not music and dialogue. If however you plug in the headphones you can hear both mixed down tracks perfectly.