The terms lossy and lossless are something I learnt recently when I discovered the format FLAC. As example MP3 is a lossy format; distorts the data on the pocess, and the end result is not exactly like the original. FLAC, on the other hand compresses the data but keeps it 1:1 with the original, just like a ZIP does.

Lagarith is the same but for video. There are some other lossless video codecs but from my experience Lagarith, using the YV12 color space when compressing, is, by far, the best. Not only in terms of file size compression, but also in terms of playback.

As an example, I've compressed r08028 at the resolution of 640x480 60fps, which is the resolution it was designed for, and it ends up as 2gb file (uncompressed is 14gb). 2gb is still quite big for a 3 minutes video but with nowadays 1TB+ HDs maybe we can start archiving our demos in this way so we can recompress them to new video formats as soon as they appear without having to mess with emulators and rendering again.

Best thing of the codec is that the playback. On a multi-core machine can play 1920x1080 60fps videos with no problems.

Unfortunately, this codec hasn't reached mainstream and it doesn't have much support yet (ie VLC doesn't play it). But if you happen to be a Windows user, give it a try!

If you want to know more about the codec, here you have some extra info, and here the sources.

Now, if only FLAC could also be used for compressing the audio that gets encapsulated in a .AVI...

EDIT: Forgot to mention. You can use this codec from kkapture itself. And if that wasn't good enough, the whole kkapture process gets way faster (compared to capture to uncompressed frames). Capturing r08028 is faster than the demo itself.