Final Cut Pro (FCP) and Soundtrack Pro (STP) have long had a symbiotic relationship, going back to the first release of the Final Cut Studio suite. One aspect of that relationship is that you can interactively edit audio track from Final Cut in Soundtrack to take advantage of Soundtrack's superior audio editing, special effects, and mixing tools.
In this Quick Tip, I'm going to show you how it's done.
Let's say you have a video clip in FCP that has a lot of background noise that you want to reduce. FCP doesn't have great noise-reduction tools, but STP does, so you can use STP's Noise Reduction feature to reduce the unwanted noise. Here are the steps.
There are actually two ways to go about sending and round-tripping audio between FCP and STP. In the first, you can control-click on the audio track you want to process, either in the Project window or in the Timeline, and choose Open In Editor:
However, this will only work if you've set up STP as your default Audio Files editor in the External Editors tab in the System Settings window (Final Cut Pro > System Settings... External Editors)
The other thing to be aware of is that using the Open In Editor feature will cause a destructive edit of your source audio - that is, changing and saving the audio in STP (or any other audio editor) will change the audio in your source footage permanently. For that reason, I think it's better to use the Send To method instead. This won't change your source audio, and you can re-edit or undo any changes you make to the source audio without losing it for good.
So, control-click on the audio track you want to process, either in the Project window or in the Timeline, and choose Send To, then choose Soundtrack Pro Audio Project from the sub-menu:
FCP has transparently replaced the audio in your Timeline with the Soundtrack Audio Project, launched Soundtrack, and opened the project in STP.
Note: I chose the option to Send only referenced media and set the In/Out Handles both to zero. Choosing Send only referenced media will ensure that you if you've edited the audio down from a larger clip, you won't be sending all that audio to STP - just the trimmed audio. Setting the Handles to zero also limits the sent audio to just the edited audio in the FCP Timeline. (You might want to change this if you're going to be cross-fading or otherwise further editing the STP-processed audio, but if you aren't, set the handles to zero to avoid confusion.)
The option to Save project with latest clip metadata is selected by default, and is recommended, so just do it.
Your FCP audio will now open in STP, and you can do your Noise Printing and Noise Reduction here (see "How-To: Remove Background noise in Soundtrack Pro" by Rounik Sethi).
Once you've processed the audio, just Save your STP Audio Project. The first time you do this, you'll see this dialog:
Usually, you want to choose the option to Reference Source Audio rather than Include Source Audio, as this will keep the STP project file size down - the audio in question is referencing back to the original FCP audio. However, if you're going to be moving the projects around to different drives or workstations, it's safer to Include the audio, so that it's contained within the STP project file.
Now just bounce back to FCP, and you'll see the audio in your FCP Timeline update with the changes you made in STP. Play your audio, and you'll hear the noise reduction (or whatever process) you did in STP.
From here, you can continue to modify the processed round-tripped audio by just Sending it back to STP, processing it there, and saving it - once you've replaced the FCP audio with the STP audio, you won't have to continually make new STP audio projects, as you'll be working in your original saved STP Audio Project.