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Playback Stutters in FCP7

P

Policar

macrumors 6502a
Original poster
Nov 21, 2004
662
7
I'm doing some editing in FCP and it's starting to stutter enough that it's difficult to use. I'm not getting any dropped frame notices, which is weird, so I think it might have to do with audio?

The footage is prores444 1080/24p and the sound is 4 channel (on average) 48khz 24bit audio. Editing off a two-drive RAID0 via esata. Footage is copied straight to the hard drive and synced with in-camera audio via timecode. In-camera audio is then deleted. It's not a problem when I first boot up but when I open any other applications or edit for a while it becomes a problem. We have tons of ram and the computer is very fast. Anyone have any ideas? It might be the hard drive, but esata should be fast enough for prores444 and four audio tracks--and it wasn't a problem when we first started editing. There is plenty of space left on the hard drive.
 
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Might sound like a stupid question, but color is the sequence's render bar? If the sequence settings are incorrect for the footage or there's a bunch of unrendered effects on the timeline, it may not play in real time.
 
I think it's all gray or light blue, native codec or rendered. Not really using any effects. I have video tracks stacked on top of each other (up to four layers total, but never more than two overlapped at once I don't think?) but only one playing at a time. Sometimes I have stacked audio tracks, too, as many as twelve but usually only four at most are enabled.

It's weird--everything will be fine and then suddenly it will get really laggy, then I restart and it's fine again.
 
Policar said:
It's weird--everything will be fine and then suddenly it will get really laggy, then I restart and it's fine again.
Click to expand...

When you say 'restart' do you mean FCP 7 or the whole machine? When it starts to really lag open up the Activity Monitor and see if something is hogging a bunch of RAM or CPU cycles. You might just have another app running w/a memory leak.


Lethal
 
LethalWolfe said:
When you say 'restart' do you mean FCP 7 or the whole machine? When it starts to really lag open up the Activity Monitor and see if something is hogging a bunch of RAM or CPU cycles. You might just have another app running w/a memory leak.


Lethal
Click to expand...

Great idea, I hadn't checked that. Not sure what to make of the results, though: The activity monitor goes up during playback, but none of the CPUS even gets closed to maxing out. FCP uses almost a gig of RAM (spotify, firefox, and flash plugin use 150MB+ each, nothing else uses much) and disk activity increases to 40MB/sec during playback (not even close to maxing out a raid array attached via esata) but playback gets slow... Don't think I'm dropping frames, either. Very weird.

I have to restart the computer, btw.
 
Blackmagic Design has a free disk speed utility. I'd run that and see what your disk performance is. 40MB/s is about one stream of 1080p24 PR 4444. What happens if you open up a clip in QT and play it back? Is it smooth or does it start to choke?


Lethal
 
LethalWolfe said:
Blackmagic Design has a free disk speed utility. I'd run that and see what your disk performance is. 40MB/s is about one stream of 1080p24 PR 4444. What happens if you open up a clip in QT and play it back? Is it smooth or does it start to choke?


Lethal
Click to expand...

Plays back great in QT and disk read is bout 240MB/sec sustained. But very choppy in FCP sometimes. Setting image quality under the RT tab to low brings things back to real time, but this is one stream of video with no effects on a 3ghz 8 core mac pro. Shouldn't happen, at least I don't think it should.
 
Try deleting your FCP User Preferences. I've had bad preferences hamper performance before. This will basically restore FCP to factory default settings so you'll need to redo preferences like capture scratch location, level of undo's, etc.,.


Lethal
 
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