[ This article was first published in the June, 2010, issue of
Larry’s Monthly Final Cut Studio Newsletter. Click here to subscribe. ]
I got burned by this when I was prepping my most recent webinar for posting. My audio slowly slipped out of sync.
I hate when that happens.
What I discovered is that the Soundtrack Pro sample rate preference setting overrides the sample rate of the Final Cut Pro project, resulting in a slow sync drift that will drive you nuts.
Because there are a variety of places where you can choose the wrong sample rate, I wanted to walk you through my process of posting a webinar to show you where the problem occurred and how to prevent it.
I record all my tutorials and webinars using Telestream’s Screenflow. When I am ready to export the file for editing, I always select “Lossless” to give me the highest quality for editing and compression.
Then, for audio, I export the file as a Linear PCM file. (See the article on choosing the right version of “Endian-ism.”)
Here’s the first opportunity you have to screw things up. Notice that the sample rate is set to 48.000 kHz. The problem is that my audio gear, like most audio gear, records at 44.1 kHz. (Both are excellent choices from a quality point of view.)
While Final Cut can easily handle both 44.1 and 48 kHz sample rates, it prefers 48 kHZ. At least, that’s been my experience when working with the Animation codec and synced audio.
So I make sure to set the audio rate to 48 kHz and export.
When getting ready to edit this in Final Cut, I create a new sequence, then drop my clip into it.
If I get a message asking if I want to change the sequence settings to match the clip, I say Yes.
Then, I remove the clip from the sequence and check Sequence > Settings. Removing the clip allows me to adjust all the settings, which can’t be done once a clip is in the Timeline. The main thing I am checking is to be sure my audio sample rate is set to 48 kHz. If not, I change it.
Once I verify my sequence settings are correct, I edit my project as normal. Because both audio and video settings of the clip match the timeline, there’s no rendering until I add effects.
Finally, I do all my audio clean-up and mixing in Soundtrack Pro. Here’s the third place the sample rate can get accidentally reset.
Before sending my file to Soundtrack Pro I SHOULD have (but didn’t) check to be sure the sample rate preference was set correctly.
To check it, go to Soundtrack Pro > Preferences > Project tab and make sure the project sample rate is set to 48000 (48 kHz).
Then, File > Quit Soundtrack Pro.
In Final Cut, select your sequence in the Browser and File > Send it to Soundtrack Pro.
When Soundtrack opens with your sequence in it, be sure the project sample rate is set to 48 kHz. You check it by looking in the top of the Soundtrack Pro tool bar. If this, too, is set to 48 kHz, all your audio sample rates match across all your programs.
At this point, you’ve maintained a consistent sample rate across all your software and elements and sync will remain constant and locked.
Yes, I’ve added this to my editing checklist.
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