Px64

Px64

An ITU standard for transmitting audio and video in 64 Kbits/sec ISDN channels (P represents number of channels used). Although video conferencing can be done in only one or two channels, more channels are required for smooth motion.

Px64 uses two screen formats. The CIF (Common Intermediate Format) generates a 352x288 resolution, while QCIF (Quarter CIF) is 176x144. CIF transmits at 36.45 Mbits/sec; QCIF is 9.115 Mbits/sec. See H.261.
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(7.) ITU-T H.261 Recommendation, Video codec for Audio Visual Services at px64 kbit/s, March 1993.
Some of the more promising include Fractal Compression, MPEG II and Px64. Each provide certain benefits though none is a clear favourite.
In a short article on the px64 standard, which was approved in 1990, Liou explains how motion video can be transmitted over digital networks [23].
The definition and planned deployment of ISDN (Integrated Service Digital Network) was the motivation for the standardization of compression techniques at the rate of px64 kbits/s where p takes values from one (one B channel of ISDN) to more than 20 (Primary rate ISDN is 23 or 30 B channels).