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H.261 came out in 1990, intended for video conferencing over Public Switched Telephone Network (PSTN) synchronous circuits. H.261 is designed to run at multiples of 64Kbps data rates from 1x to 30x.
This corresponds to the capacity of a DS0 channel, which is used to carry a single phone conversation of 8 Bit ULaw 8Khz audio. These Correspond to ISDN (2 DS0's) and E1 (31 DS0's) & T1 (24 DS0's) circuits. I was very common to use a technique called ISDN bonding allowed 2 or more IDSN lines to be used together to provide higher data rates. Companies like PictureTel dominated this space and helped write most of these stardards.
H.261 is not designed for a packet based network and doesn't work well over Frame Relay or TCP/IP Internet. Although some early streaming solutions commandeered its video compression algorithm, discarding much of communication layer and using TCP/IP instead.
When the next generation standard H.263 came out then made H.261 obsolete. H.263 has far better performance, worked better on packet networks like the Internet and can support more data rates and image sizes.
Comparison between H.261 and H.263
http://www-mobile.ecs.soton.ac.uk/peter/h263/h263.html
H261 Video coding -
http://www-mobile.ecs.soton.ac.uk/peter/h261/h261.html
H.261 Player in JAVA
H261 player and capture for windows
Thierry Turletti Home Page - Lots of great links and papers on H.261 video compression
See my site on H.263 and H.264 Video Coding
Also H.323 and H.324 Video Conferencing Documents
I am a Video compression Expert
Please contact me for assistance on Video Compression and Streaming projects.
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See my Resume