ronf/nv

Network Video early videoconferencing tool

Network Video tool

This is an archive of the source code and binaries of one of the very first videoconferencing tools available on the Internet. It was primarily written by Ron Frederick, but also includes contributions from a number of others to adapt it to support various video capture devices and compression algorithms. See the individual source files for more detailed author information.

Copyright and License

The majority of this code is copyright Xerox Corporation and is released until the following license:

Copyright (c) Xerox Corporation 1992. All rights reserved.

License is granted to copy, to use, and to make and to use derivative works for research and evaluation purposes, provided that Xerox is acknowledged in all documentation pertaining to any such copy or derivative work. Xerox grants no other licenses expressed or implied. The Xerox trade name should not be used in any advertising without its written permission.

XEROX CORPORATION MAKES NO REPRESENTATIONS CONCERNING EITHER THE MERCHANTABILITY OF THIS SOFTWARE OR THE SUITABILITY OF THIS SOFTWARE FOR ANY PARTICULAR PURPOSE. The software is provided "as is" without express or implied warranty of any kind.

These notices must be retained in any copies of any part of this software.

Some individual source files are copyright Canon Information Systems, Digital Equipment Corporation, Sun Microsystems, the Naval Research Laboratory, and the University of Southern California. See the individual source files for full copyright and license information.

Background (by Ron Frederick)

In October of 1992, I began to experiment with the Sun VideoPix frame grabber card, with the idea of writing a network videoconferencing tool based upon IP multicast. It would be modeled after "vat" -- an audioconferencing tool developed at LBL, in that it would use a similar lightweight session protocol for users joining into conferences, where you simply sent data to a particular multicast group and watched that group for any traffic from other group members.

In order for the program to really be successful, it needed to compress the video data before putting it out on the network. A goal I chose was to make an acceptable looking stream of data that would fit in about 128kbps, or the bandwidth available on a standard home ISDN line. I also hoped to produce something that was still watchable that fit in half this bandwidth. This meant I needed approximately a factor of 20 in compression for the particular image size and frame rate I was working with. I was able to achieve this compression and filed for a patent on the techniques I used, later granted as patent US5485212A: Software video compression for teleconferencing.

At the beginning of November, I released the videoconferencing tool "nv" (in binary form) to the Internet community. After some initial testing, it was used to videocast parts of the November Internet Engineering Task Force all around the world. Approximately 200 subnets in 15 countries were capable of receiving this broadcast, and approximately 50-100 people received video using "nv" at some point in the week.

Over the next couple of months, three other workshops and some smaller meetings have used "nv" to broadcast to the Internet at large, including the Australian NetWorkshop, the MCNC Packet Audio and Video workshop, and the MultiG workshop on distributed virtual realities in Sweden.

A source code release of "nv" followed in February of 1993, and in March I released a new version of the tool where I introduced a new wavelet-based compression scheme. In May of 1993, I added support for color video.

The network protocol used for "nv" and other Internet conferencing tools became the basis of the Realtime Transport Protocol (RTP), standardized through the Internet Engineering Task Force (IETF), first published in RFCs 1889-1890 and later revised in RFCs 3550-3551, along with various other RFCs that covered profiles for carrying specific formats of audio and video.

Over the next couple of years, work contined on "nv", porting the tool to a number of additional hardware platforms and video capture devices. It continued to be used as one of the primary tools for broadcasting conferences on the Internet at the time, including being selected by NASA to broadcast live coverage of shuttle missions online.

In 1994, I added support in "nv" for supporting video compression algorithms developed by others, including some hardware compression schemes such as the CellB format supported by the SunVideo video capture card. This also allowed "nv" to send video in CUSeeMe format, to send video to users running CUSeeMe on Macs and PCs.

The last publicly released version of "nv" was version 3.3beta, released in July of 1994. I was working on a "4.0alpha" release that was intended to migrate "nv" over to version 2 of the RTP protocol, but this work was never completed. A copy of the 4.0 alpha code is included in this archive for completeness, but it is unfinished and there are known issues with it, particularly in the incomplete RTPv2 support.

The framework provided in "nv" later went on to become the basis of video conferencing in the "Jupiter multi-media MOO" project at Xerox PARC, which eventually became the basis for a spin-off company "PlaceWare", later acquired by Microsoft. It was also used as the basis for a number of hardware video conferencing projects that allowed sending of full NTSC broadcast quality video over high-bandwidth Ethernet and ATM networks. I also later used some of this code as the basis for "Mediastore", which was a network-based video recording and playback service.