Why does FCP set 30fps TC Rate for certain audio clips that lack TC stream?

[David Roth weiss]

Are you sure the audio was recorded at 48khz? Check one of the original files in the Quicktime player. Could it be at 44.1khz possibly?

David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los Angeles

POST-PRODUCTION WITHOUT THE USUAL INSANITY ™

A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, and Indie Film & Documentary forums.

[Matthew Griffin]

Definitely 48k. Not sure what that would effect Timebase, but I am very happy to check anything you folks suggest!

Some of the post-sync tracks are mono, some stereo — I cannot determine any logic by which it chooses which files should stick stubbornly to TC Rate of 30!

I am tempted….with much back up….to change the TC Rate element by hand in the FCP Project files opening in BBEdit or similar. That is likely to be a bad idea, but if I can’t think of anything else, I’d rather do an annoying process 45 times by hand and know the issue is solved rather than keeping these 30fps Timebase audio files in Merges where they sound like they are drifting out of sync.

Thanks for suggesting I check the sample rate. Other suggestions?

[David Roth weiss]

Admittedly, I was reaching on that one… But, just trying to check all possibilities.

David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los Angeles

POST-PRODUCTION WITHOUT THE USUAL INSANITY ™

A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, and Indie Film & Documentary forums.

[Jeremy Garchow]

[Matthew Griffin] “When I import certain of the audio files from the location sound recordist,”

What kind of files and from what device?

[Matthew Griffin]

ah. I’m afraid I don’t know what it was — I think the recording device is the Tascam compact flash recorder. In any case, it recorded .wav not broadcast wave files on a compact flash card, which the recordist delivered to me with as a folder each for the shoot days. There are xml files for markers.xml and settings.xml but in this specific case these things don’t matter because there was no smartslate or tc generated by camera.

So these are just wave files — 48k 16bit — lacking any timebase. For some reason FCP has decided to give them a timebase instead of following the protocol of the project’s 25fps timebase. 90% of the files come through as TC Rate 25fps just fine. Those that are marked as 30fps are then out of sync with the audio tracks with picture because they are being falsely pulled down for 25fps.

I’m basically hassling with this now so my sound team doesn’t have to hassle with it when I deliver these frustrating out of sync dialogue tracks cut into seq. Trying to get the world truly back to 25fps timebase family.

Thanks for your curiosity! Does this help suggest a solution?

[Bouke Vahl]

Perhaps Spherico’s BWFtoXML tool can do something.
Otherwise, it’s no hassle for me to write something to convert them into BWF. It’s just adding a bit to the header or footer of the file.
(i’m already working on a QT to BWF tool)

I could use the file creation time to insert that as TC, hoping there is ‘some’ relationship to the footage. (at least you know the order the clips are recorded…)

Bouke

Bouke

http://www.videoToolShed.com
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[Jeremy Garchow]

Hmm. how bout this?

Choose a PAL easy setup (say DV PAL). then quit FCP.

Now reopen FCP with a new project (not your current project).

Reimport a couple of the ‘bad’ files. Do they come in @ 25 fps now?

[Russell Lasson]

I’m really confused by why the files would have a green render line when imported into a sequence. Can you open the files in QT and then get info on it, then tell us the exact specifics of the file type?

Also, how bad is the sync issue? Does the audio come before the video or the other way around?

-Russ

Russell Lasson
Kaleidoscope Pictures
Provo, UT

[Matthew Griffin]

I’ll be darned. going to a basic PAL Easy Setup and project worked! all files came in as 25fps with no problems, and I could make them dual mono and drag them into my main project without a problem.

So thanks so much! I somehow got caught up trying to fix this darned document instead of dropping it and doing my work in a project file with no history — good idea going forward!

Matt

[Matthew Griffin]

Essentially, FCP believed the lognote that the audio was 30fps and performed a pulldown to play each cluster of samples more quickly so that the TC Rate would match 25fps. Unfortunately, this was an unnecessary compensation so the 30fps stuff (for long clips) finished slightly early on the longer takes (barely noticeable otherwise).

At least I think so — I’ve just fixed this problem with the help of this thread and can’t check again to make sure.

Anyhow, this action wasn’t native-to-seq-settings playback so there were green bars on the audio track suggesting to render them for best performance.

I didn’t actually solve why this problem appeared, but the solution to import the audio and prep it in a vanilla PAL project worked perfectly!

Matt