mdr@reed.UUCP (Mike Rutenberg) (11/02/88)
The was some work (ongoing?) at Xerox PARC to do EtherPhone. They basically used a 3 MBit/s ethernet as the transmission medium and had a box less powerful than the DSP to do digitization and transmission. They claim to get pretty good performance, even with a decent offered load. I suspect the NeXT box might even be an improvement as it: uses 10MBit/s Ethernet the DSP could do more compression on the data Lots of fun ahead. Mike
jr@bbn.com (John Robinson) (11/03/88)
In article <10865@reed.UUCP>, mdr@reed (Mike Rutenberg) writes: >They [Xerox PARC] claim to get pretty good performance, even with >a decent offered load. I suspect the NeXT box might even be an >improvement as it: > uses 10MBit/s Ethernet > the DSP could do more compression on the data The DSP ought to be capable of toll-quality voice compression to 16 kbit/sec, so the 10 mbps will do lots of phone calls. Even standard phone stuff at 64 kbps isn't that much of a drain on the ether. -- /jr jr@bbn.com or bbn!jr
desnoyer@Apple.COM (Peter Desnoyers) (11/04/88)
In article <31814@bbn.COM> jr@bbn.com (John Robinson) writes: >In article <10865@reed.UUCP>, mdr@reed (Mike Rutenberg) writes: >> [stuff about EtherPhone] There are two Ethernet research phone systems I know of - Etherphone at Xerox PARC and a system at Bellcore. If anyone wants references, email me. Anyway, on the subject of real-time voice and compression: Speech compression is pretty pointless over a local ethernet unless you are using huge packets and corresponding delays. 10mS packets would take 80 bytes at 64kb, compared to well over 40 bytes for TCP/IP and ethernet per-packet overhead. Where compression wins big is when you store voice - e.g. annotation, voice mail, etc. You can do compression over larger chunks, since delay is not critical, while "bandwidth" - disk space - is much more expensive. Peter Desnoyers
jas@ernie.Berkeley.EDU (Jim Shankland) (11/04/88)
Yes, if you're clever about compression, it's possible to do real-time voice transmission at pretty low bit rates. The implications for the future are staggering: soon, any two people with telephones and 9600 bps modems may be able to call each other up and converse with each other! Jim Shankland jas@ernie.berkeley.edu "The God I believe in isn't short of cash, MISTER!"
jkrueger@daitc.daitc.mil (Jonathan Krueger) (11/05/88)
In article <26682@ucbvax.BERKELEY.EDU>, jas@ernie (Jim Shankland) writes: >soon, any two people with telephones and 9600 bps modems may be able >to call each other up and converse with each other! Um, any two people with phones can call each other up and converse with each other. Without modems. Right now. What do the modems add? -- Jon --
steele@unc.cs.unc.edu (Oliver Steele) (11/05/88)
jkrueger@daitc.daitc.mil (Jonathan Krueger) writes: >Um, any two people with phones can call each other up and converse >with each other. Without modems. Right now. What do the modems add? Simultaneous voice, pictures, text. High-bandwidth voice. Pictures and text with voice annotations. Storage of voice messages in a directory (no more fiddling with tape reels to keep a record of ideas). People will come up with more ways to use it once they get their hands/voices/ ears on it. --------------------------------------------------------------------------- Oliver Steele ...!decnet!mcnc!unc!steele UNC-CH steele@cs.unc.edu
wald-david@CS.YALE.EDU (david wald) (11/06/88)
In article <226@daitc.daitc.mil> jkrueger@daitc.daitc.mil (Jonathan Krueger) writes: >In article <26682@ucbvax.BERKELEY.EDU>, jas@ernie (Jim Shankland) writes: >>soon, any two people with telephones and 9600 bps modems may be able >>to call each other up and converse with each other! > >Um, any two people with phones can call each other up and converse >with each other. Without modems. Right now. What do the modems add? Isn't there anyone on the net with a sense of irony? ============================================================================ David Wald wald-david@yale.UUCP waldave@yalevm.bitnet ============================================================================