Webcasting

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1 Overview
2 Guidelines
3 Resources

[edit] Overview

There is an excellent article on Webcasting in the Wikipedia. Here a few excerpts from a recent version of the article...

The word webcast is derived from "web" and "broadcast". Its use has varied since the early-mid 1990s as the nature of the medium came into public use.
The generally accepted use of the term webcast is the "transmission of linear audio or video content over the Internet".

A webcast uses streaming media technology to take a single content source and distribute it to many simultaneous listeners/viewers.

The largest "webcasters" include existing radio and TV stations who "simulcast" their output, as well as a multitude of Internet only "stations". The term webcasting is usually reserved for referring to non-interactive linear streams or live events.
Rights and licensing bodies offer specific "Webcasting licenses" to those wishing to carry out Internet broadcasting using copyright material.
Webcasting is also used extensively in the commercial sector for investor relations presentations (such as Annual General Meetings), in E-learning (to transmit seminars), and for related communications activities. However, webcasting does not bear much, if any, relationship to the idea of Web Conferencing or Collaboration Tools designed for many-to-many interaction (for more discussion on this area, see our MODwiki page Video Conferencing & Collaboration Tools.

Webcasting often implies live streaming of an event, at a specified time, "broadcast" to any viewers connected to the Internet and accessing the feed. Webcasting can also mean acquiring a live event and subsequently making it available in an on-demand mode, by viewer appointment at specified times, or by request at the viewer's preference.

Webcasting is frequently interpreted as a video and/or audio stream. But the content that is acquired can be more than people or voices. Many solutions are available today to facilitate the capture of computer events, such as PowerPoint presentations or application demonstrations during a live presentation. These elements are blended together into a webcast, either as a single screen that intercuts between sources, or as multiple, integrated screens within a single user interface that isolates content sources in a synchronized display for constant viewing. Vendors of these solutions are listed in the Resources section of this wiki page, below.

[edit] Guidelines

The workflows associated with creating and distributing a webcast are predictable, but given that network or Internet protocols are involved, testing and compulsive paranoia serve well the team embarking on producing an event. Typical benchmarks in a webcast include...

[edit] Acquisition

The old adage of "garbage-in, garbage-out" applies to webcasting. The use of low-end or inadequate audio microphones and inputs, combined with minimal consumer-level video camera or cameras, produces a master signal or source that is already compromised and will become more so once encoded and compressed to match bandwidth limitations of network or Internet connections. The use of high quality equipment does not ensure, but increases the odds, that a good quality source signal is generated.

Numerous companies offer solutions for acquiring events. Some are tied to one media architecture for encoding and delivery; often using proprietary codecs, or in some cases, ISO standard MPEG-4 technologies. Some require designated presenter computers in designated classrooms, auditoriums, or meeting halls to be installed and maintained as the only source of content during acquisition. Presentations are often required to be "uploaded" ahead of a presentation to accommodate the webcasting system. In such situations, the solution requires a companion turnkey installation of encoders and servers for delivery of streams. Other companies cater to the "guerilla production techniques" often required on campuses where setup and acquisition must occur in any venue, using the presenter's personal laptop or presentation software, often with limited time for readiness-and-record.

The scope and complexity of the equipment widely varies from webcams, to single chip video cameras, to firewire capable DV cameras, and finally to industrial and broadcast quality gear. An interesting solution has been introduced by Sony. It is called the Anycast Station and is essentially a video/audio mixer in a briefcase, using professional quality microphone and audio line-in inputs, with a variety of video connectors as well. Live mixing of multiple source signals is possible. No endorsements are to be inferred, but the approach is intriguing, and perhaps worth a snapshot of the actual on-site acquisition console...

Sony Anycast Station for acquisition

[edit] Encoding

During acquisition, the incoming video and audio signals may be recorded to a hard drive in a high quality encode, or even recorded to a digital tape or optical disc. This digital master must be further downsampled or compressed in order to meet bandwidth limitations of network and Internet connections. Proprietary and open standard media architectures and codecs (associated with Windows Media, QuickTime, Real, Flash, or MPEG-4) may be employed. Some acquisition systems mix the audio and video sources and directly encode on-the-fly (usually hardware-based) the content into web-ready formats; this is necessary if a live event is occurring and being streamed immediately. If an event is produced for on-demand delivery after the event, then software and/or hardware solutions can be used to encode content after acquisition.

[edit] Server

Depending on the media architecture of choice (Windows Media, QuickTime, Real, Flash, or MPEG-4), a server or servers are used for live streaming or on-demand delivery of the acquired and now encoded event. Permutations for delivery are too varied to enumerate here. However, one decision to be made is whether to host the webcasts locally within the organization, or engage a hosted service who will manage the storage and delivery for you (via robust Content Delivery Networks).

[edit] Network Distribution

Of course, the live or on-demand content is distributed over a network or the Internet. For more information about network connections, see our wiki page Delivery of Digital Files--Network Connection Environments as well as the page devoted to Routers, Switches & Firewalls.

[edit] End User Reception

The recipient of the streamed or on-demand content must have an appropriate player or plug-in to be able to receive and display the audio/video event. Again, the nature of the encoders and servers used determines what the end user must have installed and running on a personal computer (Windows Media, QuickTime, Real, Flash, MPEG-4, Java players, and other third-party players).

[edit] Resources

Article on "WebCast" in the Wikipedia: http://en.wikipedia.org/wiki/Webcasting

StreamingMedia: http://www.streamingmedia.com/

VitalStream Whitepaper-- "Webcast Essentials": http://www.vitalstream.com/pdf/whitepaper/wp-webcast.pdf

VitalStream Guide on "Live Event Broadcasting/Webcasting over the Internet: http://www.vitalstream.com/sales/pdf/live-event-guide.pdf

QuickTime Broadcaster Overview of Live Streaming presentation, by Richard Glaser, University of Utah Mac Managers Meeting, 2005-03-16 (QuickTime movie): http://data.scl.utah.edu/fmi/xsl/stream/details.xsl?-recid=61&a::v=2iO714E199

IWA--International Webcasting Association: http://www.webcasters.org/

IWA--International Webcasting Association WIKI: http://webcasting.wikia.com/wiki/Main_Page

The Webcast Academy Book of Webcasting (collaboratively written e-book on audio webcasting): http://www.webcastacademy.net/Book_of_Webcasting

videostreaming.org Topics on Streaming Technologies (Forum): http://www.videostreaming.org/ (log in, registration, FAQ, search page); http://www.videostreaming.org/Forum/index.php (forums on media architectures, codecs & encoding, video players, etc.)

ISMA--Internet Streaming Media Alliance (formed to create specifications and open standards to define an interopreable implementation for streaming rich media (video, audio, data) over Internet Protocol (IP) networks: http://www.isma.tv

VENDORS OF WEBCAST AND COLLABORATION SOLUTIONS

Adobe Acrobat Connect (formerly Breeze): http://www.adobe.com/products/acrobatconnect/

Adobe Flash Media Server 2: http://www.adobe.com/products/flashmediaserver/

Apple QuickTime Broadcaster solution for live online events: http://www.apple.com/quicktime/broadcaster/

Apple QuickTime Streaming Server solution: http://www.apple.com/quicktime/streamingserver/

Avacaster System for webconferencing and webcasting: http://www.avacast.com/index.php?s=What-is-Avacaster

CastStream: http://www.caststream.com/

Envivio Mindshare Composer acquisition, encoding, & server solutions: http://www.envivio.com/products/webcasting_mindshare_composer.php

iVisit: http://www.ivisit.com/

Lectopia--Enterprise Lecture Capture & Distribution (iLecture), using Apple Xserve, integrates with iTunes: http://ilectures.uwa.edu.au/

Marratech solutions for corss-platform webcasting and conferencing: http://www.marratech.com/

Microsoft Windows Media and Web Distribution for Broadcasters: http://www.microsoft.com/windows/windowsmedia/forpros/content_provider/broadcast/default.aspx

On24 webcasting solutions: http://www.on24.com/

Real Networks solutions: http://www.realnetworks.com/products/media_creation.html

SonicFoundry Mediasite solution: http://www.sonicfoundry.com/mediasite/introduction.aspx

SonicFoundry Mediasite overview brochure: http://www.sonicfoundry.com/download/FileServe.aspx?market=51

Sony Anycast Station--AWS-G500 (portable video switching and audio mixing for webcasting): http://www.sonybiz.net/biz/view/ShowProduct.action?product=AWS-G500&site=biz_en_EU&pageType=Overview&category=Anycast

Sony Anycast Station 12-page brochure: http://assets.sonybiz.net/doc/bv/X/AWS-G500(brch).pdf

Starback Communications: http://www.starbak.com/products/

Streamlab Technologies: http://www.streamlab.com/stream.htm

Tegrity Campus--Classroom Capture, On-demand and podcast delivery, metadata searching, administrative management: http://www.tegrity.com

VBrick Systems: http://www.vbrick.com/

VitalStream solutions for audio and video streaming: http://www.vitalstream.com/

WebEx: http://www.webex.com/

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Webcasting

From MODwiki

Contents

[edit] Overview

[edit] Guidelines

[edit] Acquisition

[edit] Encoding

[edit] Server

[edit] Network Distribution

[edit] End User Reception

[edit] Resources

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