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Ultimedia Services Version 2 for AIX: Programmer's Guide and Reference

Overview of Ultimotion Matinee, RTV 2.0/2.1, Indeo 2.1, and Indeo 3.2 Codecs

These codecs were designed to compress video sequences, rather than still images. Each codec uses correlations between frames to try to reduce its output bit rate for a given visual quality.

Also, all of these codecs are proprietary. Ultimotion Matinee was invented at IBM, while the other codecs were developed by Intel. The RTV codecs were some of the original popular video codecs, and, initially, required special hardware. The other codecs were developed for software decoding on personal computers, before MPEG became available.

The RTV codecs are no longer popular. They were supported by the ActionMedia and ActionMedia II cards, and used the AVSS file format. Note that RTV 2.0 is just a slightly restricted version of RTV 2.0; a RTV 2.0 decoder will decode a RTV 2.1 stream. These codecs are relatively symmetric. They support two frame sizes: 128x120 and 256x240. However, because of the way the original supporting hardware was designed, RTV clips must be widened by 25% before display.

The Indeo 2.1 codec is essentially RTV 2.1 modified to use Microsoft's AVI file format. It will run in software on personal computers. It supports a range of frame sizes, but the most common are 160x120, 240x180, and 320x240. Indeo 2.1 video uses square pixels, so it will display correctly on a computer monitor without widening.

The Indeo 2.1 codec was superseded by the Indeo 3.x codecs--the latest version being the Indeo 3.2 codec. The Indeo 3.2 codec is highly asymmetric; the decoder is very fast, whereas the encoder is very complex and somewhat slow. It expands the range of frame sizes up to 640x480. Also, the Indeo 3.2 codec produces better visual quality than does the Indeo 2.1 codec.

Ultimotion Matinee is another asymmetric codec that was designed for fast decoding on personal computers. On a given PowerPC CPU, it tends to decode video faster than the Indeo 3.2 decoder. It supports frame sizes of 160x120 and 320x240.

Curiously, Motion JPEG still tends to outperform these codecs in visual quality. The RTV and Indeo codecs are next in color quality, followed by Ultimotion Matinee. RTV and Indeo 2.1 video can suffer from blurring and color smudging, and double images at scene changes or in regions of fast motion. (The RTV and Indeo 2.1 encoders in Ultimedia Services have alleviated this problem). The Indeo 3.2 codec can produce sharper images than these codecs, and is better at encoding motion.

For introductory information, see Comparison of Video Codecs.

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