Shuddering Playback Makes Editing Impossible

Question

I researched the above topic and found good suggestions in a May 31, 2007, post to remedy it. I restarted computer, changed preferences, etc.
I am running iMovie HD 6.0.3 on an iMac G5, OSX 10.4.11 with 21 GB available on HD.
I have a 5 minute project using mostly stills and a little video (no audio with video). In the first audio track there is a narration for the whole project. In the second audio track there is a little music at the opening and closing only. I do believe the problem showed up with the addition of the music track.
Hope someone can suggestion something. I panicked yesterday at this horrible jerkiness and exported it as High Quality QT movie. That plays fine. But when we tried to adjust the volume and add a title to the original project today, the playback is so jerky it makes it impossible to do so. Adjusting the volume is important.
Since this project is being done partly to show how easy iMovie is to use and the organization I work for is considering purchasing a Mac, iMovie, iDVD etc this is more than a little embarrassing. I used iMovie back in 2003 and never saw such behavior.
Would appreciate any thoughts about it. I'm stumped.
Lee
Lee

Answer 1

"..whether you have done any work with iMovie HD 6 and, if so, is this "instability" I'm encountering with '06 peculiar to my project or the '06 version?..
I've just finished an 80th birthday tribute to my cousin, using iMHD6, and have used it extensively since it first came out (..and previous versions, see small print below..) and the only real "instability" I remember finding in '06 is that if I slow down a clip, then trim it, the clip which then follows it is its original, un-slowed-down version!
Otherwise, no particular problems. I haven't had any music or audio problems ..and I make extensive audio mixes in iMovie (..which is why I stick with iMHD6 for fiddling with the audio..) ..but it's been extensively reported that if you have many individual audio clips crowding the two audio tracks, then you'll probably reach a point where everything (audio and video) starts stuttering.
(..This was isolated by Karl Petersen of these Discussions, who's not too well at the moment, but has given sterling service to everyone over many years here!..)
"..Does it occur in '08?.." ..Not that I've noticed. But audio placement in '08 is an entirely different business, and one can't edit audio - or I can't! - so precisely in '08. I do lots of frame-accurate audio trimming (..in '06..) but there just isn't that kind of precision available in '08. But for a "quick'n'dirty" rapid assembly I find '08 far faster to use than '06.
Maybe look at the source of your audio. Even though you say it's an .aiff file, how did you come by it? Was it taken from a CD or from an MP3? ..Has it been extracted by some weird means from some other source, and fed into QuickTime, or another program, and then re-saved as an .aiff? Was it recorded/turned into an .aiff at a peculiar non-standard sampling rate, instead of the (preferred) 48kHz/16-bit rate of DV video which iMovie likes?
You don't say which model of iMac you're using, but almost any iMac should be OK for standard-definition DV video in iMHD6. So I doubt that it's the hardware, nor the iMovie software. It may be some peculiar provenance of your music..