Export audio only using QuickTime Player
QuickTime Player gives you the option of exporting and sharing only the audio portion of your video. To export only the audio portion of your video, open your video in QuickTime Player. Choose Export from the File menu. Type a name in the “Export As” field. Then from the Format pop-up menu, choose “Audio Only” and click Export.
I want to burn some MP4 videos (i.e., the audio portion only) onto audio CDs; I guess that would mean converting to .aiff files, right?
Depends on how you plan to play them back. AIFF can be played on almost any commercial audio CD player. MP3 files can be played on most current CD players. Apple Lossless or AAC could be used if playback is through your computer. The choice is really yours.
Can this be done in either iTunes 10.6.1 or QuickTime Player 10.0? I'm running Mac OS 10.6.8 on a Mac mini, if that makes any difference.
Yes, but the work flow may be different depending on which software and audio compression format you use. E.G., QT 7 Pro could extract the MP4's AAC audio track directly to an new file without conversion if AAC is your target format. As previously mentioned, QT X could be use to recompress the MP4 to an audio only AAC file. The free MPEG Streamclip or QT 7 Pro apps could be used to convert the MP4's AAC directly AIFF files. Converted or extracted AAC files could be added to your iTunes library where iTunes could create and burn a "Playlist" of such files to CD using AAC, AIFF, Apple Lossless, MP3, or WAV compression formats dependin on your playback requirements. (Unfortunately, iTunes will not directly extract and reprocess/burn the AAC audio directly from MP4 files already in its library.