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History of Streaming

While there are many isolated events and micro steps that have converged to evolve today's rich and versatile range of live streaming applications and technologies, there are a few milestones that demark clear step-changes of note.

The live streaming systems in use today are all derived from voice conferencing technologies. Largely because audio requires less bandwidth to transmit over a network than video does, it is also worth noting that voice and audio streaming pre-dates video streaming and in fact the birthdate of live streaming within an Internet Protocol context is arguably the date of introduction of the Network Voice Protocol[1] on ARPANET.

While the formal RFC741 was not published until November 22, 1977, NVP was, according to that RFC, first tested in December 1973, a mere two months after TCP for “Internetworking Protocols” was introduced to the world by Vint Cerf and Robert Kahn in Sussex University (September 1973). Here is an excerpt from that RFC:

The Network Voice Protocol (NVP), implemented first in December

1973, and has been in use since then for local and trans-net real-time

voice communication over the ARPANET at the following sites:

  • • Information Sciences Institute, for LPC and CVSD, with a PDP-11/45 and an SPS-41
  • • Lincoln Laboratory, for LPC and CVSD, with a TX2 and the Lincoln FDP, and with a PDP-11/45 and the LDVT
  • • Culler-Harrison, Inc., for LPC, with the Culler-Harrison MP32A and AP-90
  • • Stanford Research Institute, for LPC, with a PDP-11/40 and an SPS-41

An unpublished memorandum from USC /ISI in April 1, 1981, by Danny Cohen is widely referenced as adding extensions to the Network Voice Protocol called the NVP-II or “Packet Video Protocol,” and this seems to mark a clear starting point for the formalization of combined real-time audio and video delivery over Internet-worked networks.

In the process of compiling this history Vint Cerf was referenced for his views on who the pioneers were when specifically looking for who did the first webcasts, and he in turn pointed us to both Danny Cohen and also to Stephen Casner of ISI. Though they were part of multiple teams, it is clear that Cohen and Casner had key insights to the creation of the first audio streaming over what was then the ARPANET.

Here is the history as communicated in an email to me by Stephen Casner:

Danny and I, along with others at ISI and at several other cooperating institutions, worked on transmission of packet voice over the ARPAnet starting in 1974. It was specific to voice rather than any audio signal because we needed significant bandwidth compression using voice coding (vocoding) to fit in the capacity of the ARPAnet. This was not voice over IP because IP did not exist yet, but it was packet voice using ARPAnet protocols.

It was not until the early 1980's that we expanded to video when a higher capacity packet satellite network called Wideband Net was installed. The first video was, indeed, crackling black & white with variable frame rate depending upon how much of the image was changing. Later we adapted commercial videoconferencing CoDecs that had been designed to work over synchronous circuits to instead work over the packet network. These provided colour and higher fidelity.

While work on developing our packet video system occurred during the first half of the 1980s, the packet video system wasn't completed and operational until 1986. The following is an excerpt from the Internet Monthly Report for March, 1986:

Multimedia Conferencing Demo

On April 1, a real-time multimedia teleconference was held between ISI and BBN using packet video and packet voice over the Wideband Net, along with the presentation of text and graphics on Sun workstations at each end. This was the first use of packet video for a working conference. Participants included BBN, ISI and SRI, plus sponsors from DARPA and NOSC.

The teleconference was the culmination of several efforts during March. Our packet video installation at Lincoln Lab was moved to BBN for ready access by the multimedia conferencing researchers there. Performance of the Voice Funnel and Packet Video software was tuned to allow maximum throughput and to coordinate the simultaneous use of packet voice with packet video. And last but certainly not least, the Wideband Net stream service and QPSK modulation were made available to provide the high bandwidth and low delay required for good packet video.

- Steve Casner

So, for the purposes of live video streaming over the Internet Protocols, the definitive birthdate of live streaming is April 1, 1986 - the day the ARPANET was turned off leaving only the Internet - although it is clear that in the context of the ARPANET a very similar range of streaming had been pioneered some years before.

It is also interesting to note that these technologies took at least 10 years to evolve into the media players and production tools that have since become increasingly familiar to today's Internet browser and connected TV users.

So what of on-demand content delivery? Well, to understand the drivers and technologies that turned file delivery into streaming content delivery, we should take a moment to think about what streaming really means.

  • [1] http://en.wikipedia.org/wiki/Network_Voice_Protocol
 
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