Converting 32 kHz clip to multiple 48 kHz clips using Batch Export

I think I've figured out a way to start with an hour long clip with 32 kHz audio, captured from a DV tape, and end up with several clips (per DV Start/Stop detection) with 48 kHz audio, saved to disk as self-contained clips. I'd like some verification that I'm doing this correctly. I currently have Final Cut Express but I'm thinking about buying Final Cut Pro for the Batch Export feature. Before I spring for FCP, I want to make sure what I'm considering will actually work. I would hate to buy FCP only to find my plan doesn't work and there's no easy (batch) way to accomplish my goal.

Here's my plan:

1. Capture an hour long DV project from tape = 1 clip. The audio is 32kHz.
2. Use DV Start/Stop Detect to automatically mark up the clip.
3. Select all the marks and choose Modify>Make Subclip. This gives you a subclip for every segment.
4. Choose Easy Setup, change settings to DV-NTSC (48 kHz).
5. Create a new sequence with the 48 kHz audio settings.
6. Open the new sequence in the timeline.
7. Drag all the Subclips to the timeline. (Advance rendering is not necessary on my Mac; all the audio can be rendered real-time.)
8. Create a new folder in the Browser
9. Select all the subclips in the timeline and drag them to the new folder in the Browser.
10. Batch export all the subclips in the new folder as Quicktime Movie, with Make Move Self-Contained checked.

Would this result in all of the subclips saved to disk, as individual self-contained clips, with 48 kHz audio?

Thanks.

PowerMac G5 Quad 2.5 GHz Mac OS X (10.4.5) NVIDIA GeForce 7800GT

Posted on Mar 2, 2006 2:11 AM

20 replies

Mar 7, 2006 11:11 PM in response to GrapeGraphics

I'm now hearing from Tom Wolski in the FCE thread indicated below, that converting audio from 32 kHz to 48 kHz in Final Cut is inadvisable.

>Don't do it through Final Cut, the audio is not clean.
http://discussions.apple.com/thread.jspa?messageID=1870418#1870418

This is in keeping with a similar recommendation by Studio X, above:

> FCP will write the audio out as 48khz but it will not

be a happy translation.

So I'm still stuck on how to use DV Start/Stop detect on a clip whose audio (not video) was converted externally, then re-imported. I'll reproduce the question I posted above with hopes that I can get someone to help guide me through this problem:

Assuming I've correctly figured out how to convert the audio file into 48kHz using Quicktime Pro, I then imported the audio file back into FCE (I don't have FCP yet). But at this point, I'm stuck.
Originally, using Mark>DV Start/Stop Detect, I marked up the original 1-hour long clip (with the 32 kHz audio). Then I selected all the marked segments (appearing under the clip in the Browser), and chose Modify>Make Subclip. That made all the segments into subclips. I could then use Batch Export (in FCP) to export all those subclips as individual clips. But those clips would have 32 kHz audio, and I want 48 kHz audio.
I'm not sure how to accomplish the same thing, with the 48 kHz audio that I've just created. If I put the original 1-hour long clip into a sequence, delete the 32 kHz audio tracks, and lay down the 48 kHz audio in its place, I get the whole 1-hour long sequence. But I can't figure out how to split this sequence up into subclips like I did with the original clip. The markers are still there (on the video clip). But what do I make into subclips? There are no segments in the browser that correspond to the sequence, only the segments under the original clip with the 32 kHz audio. It seems like I need to replace the audio of the original clip with the new audio, but I'm not sure how to do that in FCE or FCP.
I hope someone can help!

Mar 8, 2006 1:29 PM in response to Anthony M Kassir MD

That's strange... Tom had suggested we do it they way I described, and I'm sure I read that procedure in the FCE Help file... I guess the next experiment will be to split the audio and resample in an external app. This is really awkward if we have many sub clips in our capture. Tom says we should be able to run the start/stop detect after we do this conversion.

If anyone has tried this, let us know!

Jb

Mar 8, 2006 8:05 PM in response to GrapeGraphics

That's strange... Tom had suggested we do it they way
I described, and I'm sure I read that procedure in
the FCE Help file... I guess the next experiment will
be to split the audio and resample in an external
app. This is really awkward if we have many sub clips
in our capture. Tom says we should be able to run the
start/stop detect after we do this conversion.

If anyone has tried this, let us know!

Jb

If you figure out how to replace the original audio with the new 48 kHz audio and then do start/stop detection on that new clip (new clip = old video + new audio), please post back here! That's the step I'm stuck on. Can't figure out how to make a new clip from the old video + new audio.

Mar 8, 2006 11:14 PM in response to GrapeGraphics

Okay, I did it with some help from Tom. Here's a quote from the aforementioned thread:

After you've converted the audio, put the original
video and audio file into a sequence.

Delete the old audio.

Put the new audio in its place. I'll probably line up
pretty well as it should just be a file conversion.

Link the new audio with the old picture.

Drag that linked file into a bin and run DV
start/stop detect on it.

When I put the new audio under the video in the sequence, I noticed the new audio was a few frames (30 or 31) longer than the original clip. When I viewed the audio waveform in the viewer, I saw that there was empty audio at the beginning (14 frames) and end (about 16-17 frames). Setting the In and Out points for the audio, then dragging the area between the In and Out points into the timeline let me match up the audio and video perfectly.

I wonder why an additional half-second is added to the audio on each end. I think it happens when FCE exports the audio, before it is touched by Quicktime. In any case, setting edit points corrects this problem.

Linking the audio and video and dragging the linked file into the browser created a new clip and then DV Start/Stop detect worked fine.

Next step: Buy FCP (gulp-$$$) and use Batch Export, and voila! My work (for now) is done! 🙂

Mar 9, 2006 12:02 AM in response to Anthony M Kassir MD

BTW, anyone have any tips on how to make sure the audio is entirely in sync with the video, after you upsample in Quicktime, re-import, and trim the ends to match the duration of the video?

I just realized, after my last posting, if I'm setting the audio In and Out points for the audio clip a frame or two too late, the video and audio will be out of sync ever so slightly, perhaps beyond my ability to perceive it.

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

Converting 32 kHz clip to multiple 48 kHz clips using Batch Export