Anyway to generate keyframes for a divx file?

[elkinm]

I have one file that has no keyframes so seeking is quite slow. I was wondering if there is any way to generate keyframes in the file at reglar intervals without doing a full reencode. Something like taking an image from the file and at somepoints genrate a full key frame that is the current image but the key frame should consist of the parts of the partial frame blocks so there theoreticaly should not be any quality loss or compression algorithm as the frame is built directly from preveus subframes.
Also maybe make a keyframe at every point there is a complete black or unicolor frame.

Is there any program or compressor that might work something like this, and if not. is this form of key frame generation even possible?

Thanks
elkinm

[CrappoMan]

Compressed AVI frames contain the visual difference between the previous frame and the current frame, so adding a keyframe would change all the difference information from the keyframe right up to the end of the file, so the AVI would have to be fully reencoded.

Placing keyframes at monocolor or full black frames should work ok, as the difference information would be the same, but I have never come across a program that does this.

I know this is an oversimplification, as like MPEG's, there can be I, B & P frames, etc, but it should be possible.

I'm sure i'm not the only one wondering: why have no keyframes ?

Keyframes are there to keep quality. DVD MPEG2 spec has them 2 a second. DivX default is every 300 frames (~12 seconds). A full movie without keyframes must be terrible to watch after a few minutes.

Simon

EDIT: Thinking about this some more, My first point may be wrong. The visual difference would be the same, maybe not exactly the same due to quality issues, but very nearly the same, so it should be possible to add keyframes anywhere in the file, so some talented programmer out there could find a niche with this one.

[Brad31365]

What are key frames used for. Should I stop on a key frame or just a frame cutting a XviD?