Typical workflow, which is why you wait until picture lock before doing any audio work...is one of a couple options:
1) Audio mix sends you mixed STEMS...audio as separate files per track. So a Stereo L and Stereo R channel, and then if it's required, mix minus music, music only, SFX only, dialog only, VO only...and so on. As individual AIFF or BWAV files. So you can't make any changes to the audio. From this you can output a QT file, or to tape.
2) You send your fully onlined show to the post audio place and they layback the full mix to the tape.
That's the typical workflow. If you are given an AAF, you can then, as you discovered, open that in Soundtrack Pro...and then do the same thing. Export AIF or WAV tracks to bring into FCP. But there is no way to take their fully sweetened mixed audio as separate tracks into FCP for futzing.
Now, they won't have to do their whole mix over if you send them a CHANGE LIST...AAF that they can link to the current mix, that might then show what additional work needs to be done. From what I've heard, the audio guys would need a plugin in order to do that.
But seriously...don't send your audio to mix before you lock picture. It really opens a can of worms and complicates the process.
Shane
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