Jerky video

[rumplestiltskin]

I have an mpeg4 video with AAC audio. When I play it using QT Player, the video plays very "jerky". Getting info (from within QT Player) reveals 23.98 fps which, IIRC, is the film framerate.

However, if I play the video with VLC, it plays smoothly. If I convert the mp4 into H264 (for iPod) using ffmpegX, the playback remains jerky (even if I set the framerate to 29.97 in the Video tab). The jerky behavior remains even when I drop the video into my iPod and play it on my TV using the AV cable.

The original mp4 file can be dropped into my iPod but connecting the iPod to my TV results in even worse behavior. Lots of artifacts and screen flashing.

ffmpegX will not even provide an Info window on this file. Nothing happens when I click that button. It will complete a conversion (though the result has the jerky playback).

I've even converted the file (in QT Player Pro) to DV but the resulting file has only a white screen while the audio plays fine.

What I'd like is to convert the file to H264 for iPod. My settings have been 400x176, 300kbps, and using the QT checkbox. (This may be a mistake in this situation so I'm trying another conversion without this checked.)

MPEG Streamclip can't deal with the file. No matter what framerate I specify, it doesn't like it and won't start the conversion. iSquint also won't work with the file.

Is there a demux utility for an mp4 file? I don't mind doing that; sometimes working with the separate streams lets me convert things, recombine them, and then ffmpegX or MPEG Streamclip are happy and do their job.

Any suggestions will be welcome. Thanks!

[rumplestiltskin]

Solved the problem but through brute force.

1. Opened the file in VLC (where it did play okay). Used the Export Wizard to send the video out to divx3 in an "asf" container.

2. Converted the "asf" to "avi" using ffmpegX changing the framerate to 29.97 (which is required by the iPod). The resulting file had no "jerky" behavior.

3. Back to VLC where I again used the Export Wizard to send just the audio out to a WAV container.

4. Imported the wav into Audacity, normalized it to compress the volume range, and exported it as aiff.

5. Opened the asf and aiff in QT Player Pro. Copied the entire aiff track and pasted (scaled) into the asf window. Saved as a "mov" (self-contained because ffmpegX doesn't like reference movies).

6. Opened the newly combined (avi+aiff), self-contained movie in ffmpegX and converted to H264 for iPod.

I guess VLC saved my butt. If anyone knows of any other OSX app that will permit de-muxing of mp4 files, please post here.

Thanks