Here’s what I did technically:
First I hit File > Export in iMovie and clicked on “GarageBand” to transfer the video to the GarageBand application included on my Mac. In GarageBand, I added the song to the audio track. It was necessary to adjust the music to the video, e.g. to highlight a switch of the topic with the music. After some trial and error, I learned how to cut, paste, move parts of the music and also that you could simply extend a part at its beginning and end (cool!).
When the audio work was done, I wanted to add the music credits at the end of the video. I added the missing clip in iMovie and wondered how I can get the extended video into GarageBand. The trick is actually, that GarageBand will automatically load the new video because it is linked to iMovie.
It was more hassle to find a way how to get the audio track imported to iMovie. I think I only found a workaround yet: 1) Export from GarageBand to high quality video (640×480), 2) Import in new iMovie project, 3) extract audio track in iMovie. I’d be glad to hear if someone knows a better way?
From iMovie, I exported the video in a format optimized for YouTube. The video settings have been described in my previous post Screencast for YouTube with iShowU and iMovie on Mac. I configured the audio settings as follows:
- Format: AAC
- Sample rate: 22.050KHz
- Channels: Stereo
- Bit rate: 24kbps