Export from H.264 results in choppy output

Hello, I've been experiencing an issue (I don't remember it happening before the 7.4.1 update) with exporting from an H.264/AAC QuickTime movie. I used to be able to export from H.264 videos (encoded with QuickTime) with no problem. Today, I discovered that exporting any H.264 video (to DV or AIC, for instance) results in choppy output video. It happens when adding an H.264 video to an iDVD project, exporting video with QuickTime Pro, and exporting the same video from Toast Titanium 8.0.3.

Has anyone else experienced this? I've tried it on both my own H.264 QT movies as well as some of Apple's HD movie trailers. The output is always choppy (maybe ~15 fps, rough eyeballed estimate).

 

The choppiness is in the video, despite full frame rate (29.97 fps playback). I'm on an 8-core Mac Pro so I don't think system speed is the problem. And yes, you can see the choppiness on the burned DVD as well. The original H.264 videos play back perfectly smoothly, while any codec export is consistently choppy.

 

Problem solved

I've found the problem, and it's the Perian 1.1 QuickTime plugin. I removed the plugin temporarily and H.264 export now works perfectly as before. I'm going to notify the Perian developers of this problem.

[UPDATE] I've reported the problem to Perian's Trac and it's been confirmed and accepted for address. Perian Trac Ticket #320