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Desktop Video AGOCG Report

Compression in QuickTime

QuickTime uses algorithms designed as plug-in coder/decoders (CODECs), with five CODECs as standard: Photo, Animation, Graphics, Video and Compact Video.

The photo compressor is an implementation of the Joint Photographic Experts Group (JPEG) compression scheme for reducing the size of high quality still images and Apple is the first manufacturer to use this as part of its system software. JPEG, designed to compress full colour images, typically gives a compression ratio in the range of 10:1 25:1 with no visible degradation.

Some CODECs require more time to compress than they do to decompress. MPEG (a standard of the Moving Pictures Experts Group, see below) and Cinepak are examples of these asymmetrical CODECs. They are better suited for store-and-forward applications or pre-recorded video on CD-ROMs than for real time videoconferencing.

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