SYNOPSIS: When I playback a certain movie project, called VFT, in iMovie 9.0.4, the motion is smooth. If I export it, and then view the export, the motion is jerky. I haven't found a way to view it where the motion is not jerky except to view it as a "project" in iMovie itself. There is a uniform stuttering exhibited in the exports. It looks like the film stops briefly several times a second. (For a very clear alternate example of this, get the Ren and Stimpy episodes "Black Hole" and "Space Madness". The title sequence background (with the moons, planets, etc. moving from right to left) is exactly the same, but appears to run smoothly in "Black Hole" and jerkily (5 jerks per second) in "Space Madness". Can anyone here explain this?) Note: The film VFT is characterized by a lot of moving scenery.
EXAMPLES OF THE STUTTERING: I picked the two parts of the movie (called "Visuals for Timesteps" (VFT)) that best exhibit the stuttering and put them in their own project. I exported the project from iMovie using "None" for compression and "Best" for quality. I then processed them through MPEG Streamclip according to smugmug.com's recommendations and posted it. You can see it at
THE FULL STORY: I made some Super 8 movies at 18 fps in the 70s and 80s. I had them transferred to digital. I received files from the transfer company in the form of QuickTime movie files. The format: Apple Motion JPEG A, 1440 x 1080, Millions. This was a high-definition scan. No interlacing. No blended frames. Each and every frame in the file is a digital copy of each and every frame in the film.
I imported these movie files into iMovie. Ideally one would edit them at 18 fps, but that's not an option with iMovie. So I created projects using 24 fps. To preserve the speed, iMovie doubles every third frame to "stretch" each 18 frames to 24. Why did I choose 24 fps? Easier editing, smaller files, and the hope of making 24 fps progressive DVDs or even BluRays one day. Furthermore, it was recommended by two independent sources, and it taxes the computer less. I was concerned that the 3:4 pulldown would give jerky motion, but playback in iMovie looked perfectly smooth. This surprised me, but it seemed fine, so I went with it.
One of the movies is called "Visuals for Timesteps" (VFT). This is a highly unusual film in that there is a lot of motion of the entire scene a lot of the time. While this looks fine when playback is done from the project browser, there is a uniform stuttering when playing exports. It looks like the movie stops several times a second, just what you might expect from the 3:4 "pulldown", so I assume it is. (My other films mostly look okay.) And it doesn't matter what app or hardware I use to view the export: QuickTime 7, QuickTime 10, MPEG Streamclip, iPod, iPad -- it matters not. (I'm talking about _local_ playback. The Net is not involved, though I get the same effect there, too, in Firefox and Safari.)
I tried different forms of compression: Cmd-E and "Export using Quicktime" with default settings, no compression, and AIC -- all to no avail, which didn't surprise me. I even imported the AIC back into iMovie just to see if there would still be stuttering. There was.
The original 18 fps files from the transfer company play back quite smoothly, with barely a hint of jitter in certain scenes, in QuickTime 7 and 10. The import in the project browser is just slightly more jittery, and again noticeable only upon careful scrutiny of certain shots. Also, the jittering doesn't make the film look like it stops several times a second. The motion appears quite uniform in time. This is far more acceptable (and I'm fine with it) than the stuttering in the exports.
What is going on? What "magic" is iMovie doing when viewing from the project browser that can't be done in exports?
And how can I fix this? I can redo the entire project at 30 fps, which would lessen the stuttering, I would think. But this would be a tremendous amount of work! There are 45 clips, each painstakingly timed, trimmed, and speed-adjusted to match the music. Many required single-frame precision! Many had to be individually cropped to crop out conspicuous defects in the form of dust, splotches, splice gaps, and splice sprocket holes. Also, a few clips needed color correction.
Is there a way to eliminate or at least lessen the stuttering other than a redo at 30 fps? Or an easier way to convert to 30 fps? Or could I create a small virtual disk, add the raw footage and project files, modify file names and folders if needed, and post it for, or send it to, those individuals who have iMovie? Any helpful comments and suggestions are welcome.
Running iMovie 9.0.4 on OS X 10.6.8.