Audio playback problem - won't play without rendering

OK gang, I'm stumped on this one. The short story is that I've got a bunch of clips that won't play back in a timeline without being rendered. I've trouble-shot this every which way I can think of, and have come up empty.

Here's the longer version:

I got a bunch of footage of dubious provenance, shot by an amateur on an unknown camera. The footage is from some kind of tapeless camera at 1280x720 with an h.264 codec. The audio is from the camera mic, and shows up in FCP as 44.1/32-bit Floating Point.

EDIT: Forgot to add that the source clips play back in the viewer, but the audio drifts out of sync.

When I drag a clip to the timeline, and get the warning about matching the timeline settings to the clip, I click "ok". The video plays, but the audio gives me a red line.

I set the timeline settings to 44.1, still get the red line.

I run a clip through Compressor, changing the audio to IMA 4:1, 48K. Still get the red line. I double check that the timeline was switched back to 48K 16 bit. No dice.

I run it through Compressor several more times, and once through MPEG Streamclip for good measure, trying to convert to 48K audio. In Quicktime, the audio shows up as 48K. In FCP, I can play the clip and hear it. In the timeline, nothing but red lines.

What gives? What am I missing?

This sounds just like what happens if you bring clips that were captured in iMovie into FCP - the audio needs rendering every time you make the tiniest change. Those clips from iMovie have the extension .dv, which is DV Stream. Given the "unknown provenance" of those clips, anything is possible. I don't think it's the audio sample rate that is giving you the grief, it is more likely this codec conflict. Your solution would likely be to convert them to DV/NTSC or whatever codec relates to your intended environment. I'm not anywhere I can research to be more specific, maybe someone else can.

Scott

Interesting theory. Not sure if that's the problem, all my source clips are '.mov' files.

Even if they were '.dv' files, wouldn't running them through compressor and switching them to a ProRes codec resolve the problem? That's the part that stumped me -- I tried multiple conversions to a 48K format, and they still needed rendering.

I came up with a work-around. I exported the audio from my selects as an AIFF, cut that AIFF back into my timeline and linked that to my video. It's not elegant, but it works.

Still stumped by this, though. Any other thoughts?

Jeff

Quote
jwilliam
Even if they were '.dv' files, wouldn't running them through compressor and switching them to a ProRes codec resolve the problem?

I would have thought so, yes. I don't work with ProRes so I have no wisdom there.

Your workaround is what I would have suggested next.

The fact that they had the extension .mov can be misleading, it's the actual file format inside that counts. It would be interesting to see what QuickTime reports on the file format/codec on the original ones you got from your source.

The QuickTime inspector for the original source footage lists this:

Format: H.264, 1280x720, millions, AAC, 2 channels, 44100 Hz
FPS: 30
Data rate: 9.11 Mbit/sec

Looks like a Canon D5 format - you might want to review Philip Blooms workflow for this...

[philipbloom.co.uk]

The reason you cannot playback the audio without rendering is that unless the audio is WAVE or AIFF PCM uncompressed or 2:1 AIFC then you will need to render - this includes AAC, IMA, MP3, MP2 et al...

You should also bump the Audio up to 48kHz but at 16bit or 24bit not 32bit float...



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