Cinepak Compression of QuickTime Movies

Note: this page was written in 1996, and there have been a number of advances in QuickTime movie capture and compression since then. Cinepak is still a codec to consider if you want a QuickTime movie that can be played on virtually any old or new computer with QuickTime installed. -- Derek Redmond

Cinepak is a QuickTime software codec -- a method of compressing and decompressing QuickTime movies which does not require special hardware. The Cinepak compression process takes a QuickTime file, digitized in real time with a video capture card, and reduces the file size frame-by-frame. This rendering is a slow process (say ten seconds per frame), but it produces a file that can be played back efficiently in real time by most computers that have QuickTime installed.

There are a number of applications (including QuickTime Player which comes with QuickTime) that can access the Cinepak codec, to compress a movie for use in a multimedia presentation or on the World Wide Web. See Exporting Still Frames or QuickTime from Video.

This page shows still frames from Cinepak files rendered in slightly different ways from the same source material. You can download the actual Cinepak files to compare them in motion.

The original shot was captured at frame sizes of 320x240 and 160x120, at 30 frames per second using FusionRecorder software, with VideoVision Studio hardware on a PowerMac 8100/100. The data rates used by VVS were 2.7 Mb per second for 320x240, and 800k per second for 160x120. There was no audio.

The files were re-compressed to Cinepak using ConvertToMovie or Movie Cleaner Lite. They have a key frame every two seconds, are in Millions of Colors except where noted, and are "single fork" files playable by QuickTime for Windows.

The stills are JPEG files exported from representative frames in the movies, and the subtle differences between them are in some cases visible only on a monitor set to thousands or millions of colours.

160x120 Cinepak movies:

400k 10 fps, 50k per second data rate (suitable for fast WWW downloading). Compressed from the 160x120 original file.

400k 10 fps, 50k per second data rate, reduced to 256 colours using the system palette. Cinepak can create an 8-bit per pixel movie (256 colours), but the system palette usually gives blotchy results. And because of how the compression works, an 8-bit movie is usually no smaller than a 24-bit (millions of colours) movie.

400k 10 fps, 50k per second data rate, reduced to 256 colors using a custom palette. Some applications allow you to attach a custom palette to a movie. Movie Cleaner will create a palette from a PICT file exported from Movie Player. This is better than the system palette, but 8-bit still has no advantage over a 24-bit movie in most cases. (And this example has intermittent white speckles -- Debabelizer, from Equilibrium Technologies, provides tools for controlling dithering and palette to eliminate this kind of problem, and a super-palette that will not shift when you switch from playing one movie to another.)

700k 15 fps, 100k per second data rate (suitable for any CD-ROM player.) Better resolution, and the motion is slightly smoother because of using more frames per second. The 100kps data rate is the highest Cinepak wanted to utilize for this frame speed and size.

700k 15 fps, 100k per second, mild blur added. Some applications allow blurring the image slightly to compensate for the reduced resolution when compressing. It is difficult to keep the blur from being too obvious in a 160x120 picture. This movie is also an example of a 24-bit (millions of colours) movie with a custom palette attached, which improves how it looks when it plays on an 256-colour monitor.

Look at three versions of this same movie frame rendered at the larger frame size of 320x240 pixels (120k page).

See also a page demonstrating Sorenson compression, which provides more efficient compression of movies, but requires QuickTime 3+.

For other Web resources related to QuickTime and digital video, go to the FILM 410* Course Materials page.