Quicktime Codecs

Date:    Wed, 24 Aug 1994 13:32:55 +0500
From:    Anh-Tuan Duong <duong@ERG.SI.UQAM.CA>

There has been some discussion about which kind of compression will yield the best results when producing animations in quicktime. Since it all depends on the type of anymation you produce, I'll try to shed a bit of light on the various compressors you can select:

None
This one is pretty straight forward. Good format to keep RAW material. Will not play at acceptable speeds if the images are too big.
Jpeg
Uses an algorithm which compresses the picture using a matrix for the hue and a Lempel-Zev compressing for lightness. This is a good inter- mediate storage format (if you need space). Will only playback at full rate with special hardware.
Video
General good purpose compressor for video tape. Since a video signal has more noise than a clean computer generated graphic, this codec can handle extra pixilations and color shifts much better than the other ones.
Cinepak
Almost the same as above but uses a 4x4 matrix and all pixels in that matrix can be turned into a single color. The benefit is a 10 to 1 compression ratio from the original file. Unfortunately it's also the slowest to compress. Be prepared to wait when compressing (not in plaback). So great for video signal source material.
Animation
Well suited for computer generated files where there is NO noise. This codec can keep an alpha channel if you set it to millions+. Good for 16- bit or 24-bit animations.
Graphic
Similar to the above but this one only works in 256 colors.

We've done some tests. We generated a 2 meg PICS file with objects moving around in a 320 x 240 window. The file was compressed using 3 codecs. All were done (except the Cinepak one) in 256 colors with a custom palette. No dithering was used. Here are the results:

Compression Size Notes

None 2 Megs

Cinepak 1.8 Megs Picture quality was lowsy

Animation (256) 1.6 Megs

Graphics 435 K Yowser!

Compression	Size	Notes
None	2 Megs
Cinepak	1.8 Megs	Picture quality was lowsy
Animation (256)	1.6 Megs
Graphics	435 K	Yowser!

So if you're doing animations, try using the graphics compressor. For some animations, it's the best way to go (it's often overlooked).

We've also used it to compress video material at 256 colors using dithering and the system palette. The results were suprisingly good. This was a special case where the video had to run in 256.