Packetizer

A history of video conferencing (VC) technology

"This 'telephone' has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us." -- Western Union internal memo, 1876.

Picurephone, 1964
The Bell system Picturephone, 1964

Sources : Wall Street Journal (27 February 1996), The MBone FAQ, rem-conf listserv, The MBone listserv, CU-SeeMe listserv, RTP: Historical Notes, and few PostScripts (*.ps).

Notes and References

[1] Danny Cohen, "Specifications for the Network Voice Protocol (NVP)", RFC 741, Internet Engineering Task Force, November 1977.
"The major objective of ARPA's Network Secure Communications (NSC) project is to develop and demonstrate the feasibility of secure, high-quality, low-bandwidth, real-time, full-duplex (two-way) digital voice communications over packet-switched computer communications networks. The Network Voice Protocol (NVP), implemented first in December 1973, and has been in use since then for local and transnet real-time voice communication over the ARPANET."

[2] Randy Cole, "PVP - A Packet Video Protocol", Internal Document, USC/ISI, July 1981.
"The Packet Video Protocol (PVP) is a set of extensions to the Network Voice Protocol (NVP-II) and consists mostly of a data protocol for transmission of video data. No specific changes to the NVP-II protocol are necessary for the PVP."

[3] Eve M. Schooler, "A Distributed Architecture for Multimedia Conference Control", ISI research report ISI/RR-91-289, November 1991.
"Voice Terminal (VT) program and Packet Video Program (PVP) were originally implemented on a BBN Butterfly multiprocessor. VT and PVP digitize and packetize data, using the Netowrk Voice Protocol (NVP) for audio and the Packet Video Protocol (PVP) for video. They transmit this data across the network using the experimental Stream Protocol (SP) and the Terrestrial Wideband Network (TWBnet)."

[4] DARTnet : A trans-continental IP network of about a dozen research sites connected by T1 trunks.
November 1988, small group (MIT, BBN, UDel, ISI, SLI, PARC, LBL) led by Bob Braden of USC/ISI proposes testbed net to DARPA. This becomes DARPA Research Testbed Net (DARTnet).
DARTnet has since evolved to CAIRN, which presently connects 27 institutions in the US and Britain.

[5] Tim Dorcey, "CU-SeeMe Desktop VideoConferencing Software", Connexions, Volume 9, No.3, March 1995.
"In fact, it was Paul Milazzo's demonstration of such a tool in 1991 that inspired development of CU-SeeMe."

[6] The video used for the July 1992 Internet Engineering Task Force (IETF) was the Desktop Video Conferencing (DVC) program from BBN, written by Paul Milazzo and Bob Clements.
They have made available a receive-only program, but they retain a proprietary interest in the version that is capable of sending.
This program has since become a product, called PictureWindow.

[7]INRIA Videoconferencing System (IVS) was used to broadcast part of the IETF 25 meeting held in Washington, DC during 16-20 November, 1992. The broadcast was sent over the Mbone. See Internet Monthly Report published in November 1992.

[8] "When development of CU-SeeMe began in July 1992, the only real-time videoconferencing software for the Internet required expensive hardware which severely limited the number of potential senders and receivers. Working with Richard Cogger in the summer of 1992, Tim Dorcey wrote the original version of CU-SeeMe."
URL: http://cu-seeme.cornell.edu
As the Macintosh did not have IP multicast support, CU-SeeMe took a more traditional approach and developed a multipoint server (Reflector) that CU-SeeMe clients could connect to.

[9] For the November 1992 IETF and several events since then, they have used two other programs.
The first is the Network Video (nv) program from Ron Frederick at Xerox PARC.
Also available from INRIA is the IVS program written by Thierry Turletti (as mentioned previously).
Van Jacobson, "Old timers might remember that the first, binary-only, release of nv happened 24 hours before the November 1992 IETF where it was first used."

[10] vic (vi/deo c/onfernece) was inspired by nv. Portions of vic (the ordered dither, the nv-format codec, and some of the video capture code) were derived from the nv source code.
An early version of vic was used by the Xunet research community to carry out distributed meetings in Fall 1993.
vic change history at http://www-nrg.ee.lbl.gov/vic/CHANGES.html

[11] In 1991, 5 high school friends established ClassX, a start-up software company, at Raanana, Israel.
2 years later, 4 members of them joined VocalTec and they have developed the VocalChat v1.0-2.5, and the Internet Phone.
Ofer Shem Tov, "VocalChat early version was introduced first time in PCEXPO end of June 1993 in New York. It did half duplex calls over Novell IPX networks. VocalChat v1.0 was released in Comdex Fall, November 1993, in Las Vegas, it was a finished version of the PCEXPO product. First long distance call was done on Bell South Novell network from Atlanta to Miami. VocalChat 2.02 LAN and WAN were released in June 1994 and included voice mail, address book, TCP/IP support and support of VocalTec Compression Card (VCC) for low bandwidth links.
VocalChat GTI (Gateway To the Internet) was released in October 1994. It was focused on the Internet and required the VCC card."

[12] Charley Kline, "I got annoyed at the Fall 1992 IETF when told that the only serious platform for multimedia conferencing was a hefty Unix workstation. I figured a Macintosh has better audio processing ability than a Sun (true!), so set about to write an audio conferencing tool for the Macintosh that would interoperate with the popular vat program for Unix."
URL: http://spiffy.ci.uiuc.edu/~kline/cvk-ido.html

[13] Henning Schulzrinne, "Real-time Transport Protocol (RTP) is the Internet-standard protocol for the transport of real-time data, including audio and video. It can be used for media-on-demand as well as interactive services such as Internet telephony. RTP consists of a data and a control part. The latter is called RTP Control Protocol (RTCP)."
RTP has its roots in the early work done using Network Voice Protocol 2 (NVP-II) with vat, vt and nevot in 1991, which in turn has its roots in the Network Voice Protocol (NVP) experiences in the early 1970s.

[14] H.323 : "Visual telephone systems and equipment for Local Area Networks which provide a non-guaranteed Quality of Service." (original title)
"Packet-based multimedia communications systems." (revised title in H.323 v2 drafts)
4 main H.323 network components; Terminals, Gateways, Gatekeepers, and Multipoint Control Units (MCUs).
H.320 (N-ISDN), H.321 (B-ISDN, ATM), H.322 (GQoS LAN), H.323 (H.320 over LAN), H.324 (SCN), H.324 M (Mobile).

[15] Toby Nixon, "Microsoft NetMeeting version 2.0 and below uses an alternative call setup procedure that is permitted for combined H.323/T.120 terminals. Because NetMeeting was originally a T.120-based product (without H.323 support), it sets up the T.120 (data conference) call first, and then the H.323 (audio and video conference) call."
Current versions of NetMeeting are not compliant with the H.323 standard as they do not attempt to register with a gatekeeper, a required function.

[16] SIP is a simple signaling protocol for Internet conferencing and telephony.
H.323 is an ITU-T standard, while SIP is the IETF approach.

The pioneering video conferencing tools :