Why are some of my exported tracks from Logic Pro distorted?
November 24, 2016 9:31 AM   Subscribe

I use Logic Pro to record (and edit) my podcasts, and twice in the past two months I've gotten distorted tracks that can best be described as sounding like the Breen from Star Trek. Why is this happening? Garbled track here.

Bullet point style, to get across the relevant information:

1) I record two tracks (one for me, one for cohost) then use the File-->Export-->All Tracks As Audio Files command to generate two .wav files which I then edit (also in Logic Pro.)

2) Twice in the past 2 months, I've had both .wavs come out garbled. The first and second times were with different audio interface devices and different USB cables.

3) I've uploaded one of the tracks, links above and below.

4) Why is this happening?

5) Is there any way to fix these tracks so we don't need to redo an entire episode? I'm self-taught with this stuff and I've gotten passably good, but this is well above my skill level.

Another link to garbled audio.
posted by Automocar to Technology (9 answers total)
I just opened your .wav in Audacity and had a look at it. It's pretty messed up. It's not something simple like clipping; there are regions where your sound seems to have been chopped into chunks, where half of each run of 128 samples has gone missing. If that's your raw audio, I fear that (5) is a No.

Why is it happening? Could be anything from a deliberate effect accidentally applied to a RAM fault. You might want to try alternative software (Audacity is cross-platform and free) to see if you can narrow down the range of possible causes.
posted by flabdablet at 10:13 AM on November 24, 2016 [1 favorite]

I don't know why your tracks are coming out garbled, but I'm confused about your process. Why are you recording the tracks, exporting them, then reimporting them? Couldn't you just record them, edit them, then bounce the whole project when you're done (even with non-destructive editing, saving a backup of the originals after recording isn't a bad idea here)?

Do the tracks play back distorted when you just play them in Logic before you export them?
posted by zachlipton at 11:22 AM on November 24, 2016

Why are you recording the tracks, exporting them, then reimporting them?

I... don't have a good answer for that? Mostly because I don't always edit right away so I figured getting the files out was the way to do this, but you're right, I could just save the project and when I'm ready to edit, load that saved project. Thanks for the idea!
posted by Automocar at 11:28 AM on November 24, 2016

Is the audio in Logic Pro garbled when you play it back, or just after you export it?
posted by speicus at 12:04 PM on November 24, 2016 [1 favorite]

Is the audio in Logic Pro garbled when you play it back, or just after you export it?

I don't seem to have this anymore, so I can't test it.
posted by Automocar at 12:29 PM on November 24, 2016

Can you reproduce the problem? Hard to diagnose it without knowing if it's the recording or the exporting.

Sonically, it sounds like a sample rate conversion issue, but I'm not sure at what point in the chain it would be happening.

Your audio file is probably permamently borked though. :(
posted by speicus at 2:42 PM on November 24, 2016

So that you know, I'm assuming you're using Logic Pro X.

If it's the same Logic Pro document you recorded to originally, can you revert to the oldest saved version (File > Revert to...)? Perhaps that's got the clean recording.

Did you check after recording but before bouncing that it was clean?

Alternatively if you want to inspect the files that the LPX document has stored (there might be something useful there that's not necessarily on the timeline), either go to the Project Audio (Window > Open Project Audio), or if you hold down the Control key (labelled ctrl on most keyboards) and click on the Logic Pro X file, then select Show Package Contents from the menu that pops up. There's an Audio Files folder in there, which contains all the audio related to the document - select one, then press the space bar and it will preview the file so you can hear what it sounds like.

FWIW, I've had a very similar distortion playing back files when the drivers on an audio interface (I think a Behringer 610) went awry, though in that case, since I was just playing back, the files were fine and I just needed to restart the Mac.
posted by Grangousier at 4:23 PM on November 24, 2016 [1 favorite]

Things that I would check:
  1. Check that the project sample rate and audio interface sample rate are the same. My interface refuses to work unless this is the case, but YMMV.
  2. Uninstall the software for your audio interface using AppCleaner or your personal preference for uninstallation of software. Reinstall the latest software for your interface.
  3. Use AppCleaner to uninstall Logic and reinstall it.
  4. Check your RAM.

posted by prismatic7 at 4:37 PM on November 24, 2016 [1 favorite]

Your problem sounds somewhat like the issue CGP Grey and Myke Hurley discussed in the latest episode of Cortex. Specifically, in answer to the question beginning at 1:37:10, where they mention a bug they've recently found in Logic that's triggered by their collaborative editing process: Myke does the first edit, then sends the audio to Grey, and when Grey returns the audio to Myke after his edit, "there's this horrific noise gate compression put on it that [Myke has] to fix". If that sounds familiar, perhaps you can contact Myke for more information, or ask in the official discussion thread on Reddit.

Caveat--I know next to nothing about audio editing, so I'm not sure if noise gate compression is a reasonable description of what is wrong with your files...
posted by yuwtze at 11:33 PM on November 25, 2016

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