There are a lot little "fine prints" you have to be aware of when exporting a movie in Logic
- When you export your Move in Logic, you don't actually export a movie
- When using the "Export Audio to Movie" command, Logic will make a copy of the movie file with the identical movie properties, only changing the audio tracks of the movie file
- That command prompts two dialog windows.
- Dialog 1: This is the standard Save Dialog where you determine the Finder Location in a edition to the audio format (PCM, AAC, Bit Depth, Sample Rate)
- Dialog 2: This is the important "Choose tracks to export Dialog" that opens when you click the Save button on the Save Dialog.

Choose tracks to export Dialog
- On top are all the tracks listed that are embedded in the original video file (usually only one track
- Keep in mind that each track can have 1 channel (mono), 2 channels (stereo), or multiple channels (surround)
- The checkbox determines if you want to keep the original audio track(s) that was embedded in the video.
- In most cases you would disable this checkbox, because you might have imported that audio track to Logic (during your initial movie import) and mix that together with your new tracks that you composed for the video
- The checkbox "on separate tracks" at the bottom is the important one.
On separate tracks
- Disabled: Logic mixes all the audio tracks to a single audio track and embeds that in the video file. These tracks are your Logic Project output and any original video track that you have enabled in the checkboxes above. Again, keep in mind that a Track can be mono, stereo, or multi-channel
- Enabled: Logic creates separate Tracks in the video file. That means individual Tracks for each Track that you kept (checkbox on top) and the last Track would be the output of your Logic Project.
YouTube Problem
It seems that when YouTube encodes an uploaded video that has multiple tracks, it uses only the first track and ignores any additional tracks. That means, when you have exported such a video (with multiple tracks), then your QuickTIme player will play all tracks, but YouTube will ignore the Track that represents your Logic output (because it is not Track No 1).
Logic Bug
To make it even more confusing, it seems that there is a bug in Logic. That important checkbox "on separate tracks" disappears from the Dialog 2, when you use the "Export Audio to Movie" command a second time. You have to quit and relaunch Logic again to make it appear again.
Sorry for the rather long explanation, but I hope it helps to solve the problem and good luck with the competition
Edgar Rothermich
Graphically Enhanced Manuals
www.LogicProGEM.com