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Podcasting is a term used to describe a collection of technologies for automatically distributing audio and video programmes over the Internet using a publisher/subscriber model. It differs from earlier online collections of audio or video works because it automatically transfers the files to the user's computer for later use; it is one example of push technology. Podcasting enables independent producers to create self-published, syndicated "radio shows," and gives broadcast radio or television programs a new distribution method.

Any digital audio player or computer with audio-playing software can play podcasts. From the earliest RSS-enclosure tests in 2000 and 2001, feeds have been used to deliver video files as well as audio, and other media such as photographs and text are transferable by podcast. The term "cast", however, still refers largely to audio distribution.


Name

"Podcasting" is a portmanteau that combines the words "iPod" and "broadcasting."

The term is often thought to be a misnomer since neither podcasting nor listening to podcasts requires an iPod or any portable player, and no broadcasting is required. The term is also sometimes criticized as giving undue credit to Apple for a technology which it had very little to do with creating. Aware of this potential misunderstanding, some writers have suggested alternative names. One such alternative is "blogcasting", which implies content based on, or similar in format to, blogs. Others include "audioblogging" and "rsscasting". Some writers have also suggested reinterpretations of "pod", such as "Personal, On-Demand" or phonetically "Portable Audio".[1]

Podcasting as a medium is not limited to audio data. Podcasting of video data is called, among other things, "video blogging" (see vlog), "video podcasting", "vlogging", "vodcasting", or "vidcasting".

Mechanics

Podcasting is an automatic mechanism by which computer files are transferred from a server to a client which pulls down XML files containing the addresses of the media files. In general, these files contain audio or video, but also could be images, text (e.g. PDF), or any file type.

A podcast is generally analogous to a (non-live) television or radio series.

The content provider begins by making a file (for example, an MP3 audio file) available on the Internet. This is usually done by posting the file on a publicly-available webserver; however, BitTorrent trackers also have been used, and it is not technically necessary that the file be publicly accessible. The only requirement is that the file be accessible through some known URI (a general-purpose Internet address). This file is often referred to as one episode of a podcast.

The content provider then acknowledges the existence of that file by referencing it in another file known as the feed. The feed is a machine-readable list of the URIs by which episodes of the show may be accessed. This list is usually published in RSS format, which provides other information, such as publish dates, titles, and accompanying text descriptions of the series and each of its episodes. The feed may contain entries for all episodes in the series, but is typically limited to a short list of the most recent episodes, as is the case with many news feeds.

The content provider posts the feed to a known location on a webserver. (Unlike the episode file itself, the feed is published to a webserver, usually not by other means.) The location at which the feed is posted is expected to be permanent. This location is known as the feed URI (or, perhaps more often, feed URL). The content provider makes this feed URI known to the intended audience.

A consumer enters this feed URI into a software program called a podcatcher or aggregator (the former term is specific to podcasting while the latter is general to all programs which collect news from feeds). This program retrieves and processes data from the feed URI.

A podcatcher is usually an always-on program which starts when the computer is started and runs in the background. It manages a set of feed URIs added by the user and downloads each at a specified interval, such as every two hours. If the feed data has substantively changed from when it was previously checked (or if the feed was just added to the podcatcher's list), the program determines the location of the most recent episode and automatically downloads it to the user's computer. Some podcatchers, such as iTunes, also automatically make the newly downloaded episodes available to a user's portable media player. (This is only the typical behavior of a podcatcher; some podcatchers behave—or can be set to behave—differently.)

The downloaded episodes can then be played, replayed, or archived as with any other computer file.

Compared with streaming

Unlike streaming media, podcasting is not live data transfer. Streaming media is more like traditional broadcast radio and television, while subscribing to a podcast is closer to joining a CD-of-the-month club.

Podcasting provides a more suitable means of transferring high-quality content to users with low-bandwidth low data rates and high latency do not adversely affect the quality of the content as they do with streaming.

Programs distributed by podcasting are not transient; streamed programming is. With streaming media one must capture data as it is received, while a podcast episode is received already in archived form. (This distinction makes a podcast legally distinct from a streamed webcast.)

History

Initial development

What makes podcasting unique from other digitalized audio technologies is the use of syndication feed enclosures to automatically download audio files for those subscribed to the particular feed. The concept of using syndication feeds for this purpose originated with a draft proposal by Tristan Louis[2], in addition to conversations between Dave Winer, author of the Really Simply Syndication (RSS) format, Adam Curry[3], and others representatives from the blogging world and online radio broadcasting industry. To facilitate this functionality, Winer created a new version of RSS, RSS 0.92[4], adding a new element[5], enclosure[6]. He demonstrated, publicly, how it would work by enclosing a Grateful Dead song, January 11th, 2001[7].

The use of the enclosure element to push audio files originally had slow acceptance among webloggers and tool developers. Winer incorporated RSS enclosures into the Userland weblogging product, Radio. Since Radio had a built-in aggregator, it provided end-to-end podcasting support, though the term most used at the time was audio-blog or audioblog.

In June 2003, Stephen Downes demonstrated aggregation and syndication of audio files using RSS in his Ed Radio application [8]. Ed Radio scanned RSS feeds for MP3 files, collected them into a single feed, and made the result available as SMIL or Webjay audio feeds. In September of that same year, Winer created an RSS-with-enclosures feed for his Harvard Harvard Berkman Center colleague Christopher Lydon. In his announcement of Lydon's audio-enclosure feed, Winer challenged other aggregator developers to support this new form of content and provide enclosure support. Not long after this challenge, Pete Prodoehl released a skin for the Amphetadesk aggregator that displayed enclosure links.

A month later, in October of 2003 at the first Bloggercon weblogger conference held at Harvard, Harold Gilchrist and Kevin Marks demonstrated a script to download RSS enclosures and pass them to iTunes for transfer to an iPod[9]. Following the conference, Curry offered his blog readers a RSStoiPod script that would do the same. He assigned an open source license to the script (which he called 'iPodder'), and published it online at ipodder.org; encouraging other developers to build on the idea.

Possibly the first use of the term "podcasting" was as a synonym for audioblogging in an article by Ben Hammersley in The Guardian on February 12 2004 [10]. The name wasn't widely adopted until that fall. In September of 2004, Dannie Gregoire also used the term to describe the automatic download[11] and synchronization of audio content; he also registered several 'podcast' related domains. His and Hammersley's use of 'podcast' were picked up by leading podcasting evangelists such as Winer and Curry and entered common usage.

By October 2004, detailed how-to podcast articles[12] had begun to appear online, and a month later, liberated syndication libsyn launched what was apparently the first Podcast Service Provider, providing storage, bandwidth, and RSS creation tools.

Precursor

Prior to the Internet, in 1970s, RCS, Radio Computing Service provided music and talk related software to radio stations in a digital format. Prior to online music digital distribution, the midi format as well as the M-Bone, Multicast Network was used to distribute audio and video files. The M-Bone was a multicast network over the Internet used primarily by educational and research institutes, but there were audio talk programs. Source: Publisher: National Association of Broadcasters, Internet Age Broadcaster I and II. Author: Peggy Miles and Dean Sakai

Many other jukeboxes and websites in the mid 1990's provided a system for sorting and selecting music or audio files, talk, sequeway announcements of different digtal formats. There were a few websites that provide audio subscription services.

The development of downloaded music did not reach a critical mass until the launch of napster.com, another system of aggregating music, but without the subscription services provided by podcasting or video blogging aggregation client or system software.

Independent of the development of podcasting via RSS, a portable player and music download system had been developed at Compaq Research as early as 1999 or 2000. Called PocketDJ, it would have been launched as a service for the Personal Jukebox or a successor, the first hard-disk based MP3-player. See appropriate section in the Personal Jukebox article.

Popularization

The word about podcasting rapidly spread through the already-popular weblogs of Curry, Winer and other early podcasters and podcast-listeners. Fellow blogger and technology columnist Doc Searls began keeping track of how many "hits" Google found for the word "podcasts" on September 28 2004, when the result was 24 hits. [13] There were 526 hits for "podcasts" on September 30, then 2,750 three days later. The number doubled every few days, passing 100,000 by October 18. As of November 24, 2005 Google reported 103,000,000 hits for "podcasts".

Capturing the early distribution and variety of podcasts was more difficult than counting Google hits, but before the end of October, The New York Times reported podcasts across the United States and in Canada, Australia and Sweden, mentioning podcast topics from technology to veganism and movie reviews. [14] USA Today told its readers about these "free amateur chatfests" the following February [15] [16], profiling several podcasters, giving instructions for sending and receiving podcasts, and including a "Top Ten" list from one of the many podcast directories that had sprung up. The newspaper quoted one directory as listing 3,300 podcast programs in February, 2005.

Those Top Ten programs gave further indication of podcast topics: four were about technology (including Curry's Daily Source Code, which also included music and personal chat), three were about music, one about movies, one about politics, and—at the time number 1 on the list—The Dawn and Drew Show, described as "married-couple banter," a program format that USA Today noted was quite popular on American broadcast radio in the 1940s. Such "couplecasts" have since become quite popular among independent podcasts (those not derived from a preexisting radio show).

In March of 2005, John Edwards became the first national-level US politician to hold his own podcast [17]. (He may be the first major politician to have a podcast; given the nature of podcasting, we may never know.) Within a few episodes, the show had all the features of a major podcast: a web site with subscription feeds and show notes, guest appearances, questions from the audience, reviews and discussion of other media (in this case books), musical interludes of podsafe (noninfringing) songs, light banter (sports and recreation talk), even limited soundseeing from on location.

By mid-2005, the medium had acquired a bittersweet form of validation: a backlash. Some experienced Internet users declared podcasting to be either nothing special (just a variant of blogs and mp3s), or already past its peak (because of growing exposure, and/or adoption by unsavvy Internet users).

In June, 2005, Apple added podcasting to its iTunes 4.9 music software and iTunes Music Store, staking a claim to the medium. The iTunes software downloads and organizes podcasts, and loads them on the iPod, taking the place of a separate aggregator application. In addition, iTunes 5 interfaces with the online Music Store, which compiles and distributes the content. As of October 2005, the Music Store is free of charge to both the listener and creator.

A little over a month later, U.S. President George W. Bush became a podcaster[18], when someone added an RSS 2.0 feed to the previously downloadable files of the weekly radio addresses at the White House website.

As is often the case with new technologies, pornography has become a part of the scene - producing what is sometimes called podnography. Other approaches include enlisting a class full of MBA students to research podcasting and compare possible business models, [19] and venture capital flowing to influential content providers.

The growing popularity of podcasting introduced a demand for music available for use on the shows without significant cost or licensing difficulty. Out of this demand, a growing number of tracks, by independent as well as signed acts, are now being designated "podsafe". (See also Podcasting and Music Royalties.)

In September 2005, the first podcast encoded in full Dolby 5.1 Surround Sound, was created by Revision3 Studios with their 14th episode of Diggnation. The Dolby encoding lasted for only a few minutes of the podcast.

On October 12, 2005 Apple Computer CEO Steve Jobs unveiled the first iPod with video capabilty. In his keynote speech he demonstrated the video podcast Tiki Bar TV.

On December 03, 2005 Sony Computer Entertainment America unvailed that the PSP would have Podcasting using the RSS Channel feature. The PSP is able to use Podcasting by upgrading to 2.60. Sony

Adoption by traditional broadcasters

Main article: Podcasting by traditional broadcasters

Traditional broadcasters were extremely quick to pick up on the podcasting format, especially those whose news or talk formats spared them the complications of music licensing. The American syndicated radio show Web Talk Radio[20] became the first to adopt the format, in September 2004, followed within weeks by Seattle news radio station KOMO and by individual programs from KFI Los Angeles and Boston's WGBH.

The BBC began a trial in October 2004 with BBC Radio Five Live's Fighting Talk. These trials were extended in January 2005 to BBC Radio 4's In Our Time[21]. Also in January 2005, CBC Radio began a trial with its weekly national science and technology show Quirks and Quarks[22], which has offered listeners Real Audio, MP3 and OGG downloads since February 1996. The CBC trial also included CBC Radio 3's Canadian Music Podcast as well as limited podcasting of CBLA's popular Metro Morning Toronto show. United States National Public Radio member stations WNYC and KCRW adopted the format for many of their productions. March saw Virgin Radio become the first UK radio station to produce a daily podcast of its popular breakfast show. In April 2005 the BBC announced it was extending the trial to twenty more programs, including music radio[23] and in the same month Australia's ABC launched a podcasting trial across several of its national stations[24].

In May, 2005, the trend began to go the other way, with podcasts becoming a source of content for broadcast radio programs by Adam Curry, Christopher Lydon and others. The entire format of KYOU Radio, a San Francisco radio station, became based around broadcasting Podcasts. That summer, when the Canadian Broadcasting Corporation locked out more than 5,000 of its regular on-air and technical staff, they responded by creating their own unofficial podcast of original programming, CBC Unplugged, which also appeared on some campus and community radio stations, including CIUT in Toronto and CFRU in Guelph, Ontario.

Coping with growth

While podcasting's innovators took advantage of the sound-file synchronization feature of Apple Computer's iPod and iTunes software -- and included "pod" in the name -- the technology was always compatible with other players and programs. Apple was not actively involved until mid-2005, when it joined the market on three fronts: as a source of "podcatcher" software, as publisher of a podcast directory, and as provider of tutorials on how to create podcasts with Apple products GarageBand and Quicktime Pro.

File:Itunespodcast.png
The podcasting selection views of iTunes 5.0

When it added a podcast-subscription feature to its June 28, 2005, release of iTunes 4.9[25], Apple also launched a directory of podcasts at the iTunes Music Store, starting with 3,000 entries. Apple's software enabled AAC encoded podcasts to use chapters, bookmarks, external links, and synchronized images displayed on iPod screens or in the iTunes artwork viewer. Two days after release of the program, Apple reported one million podcast subscriptions.[26]

Some podcasters found that exposure to iTunes' huge number of downloaders threatened to make great demands on their bandwidth and related expenses. Possible solutions were proposed, including the addition of a content delivery system, such as liberated syndication; Podcast Servers;Akamai; a peer-to-peer solution, BitTorrent; or use of free hosting services, such as those offered by Ourmedia, BlipMedia and the Internet Archive.

As of September 2005, a number of services began featuring video-based podcasting including Apple via its iTunes Music Store and Loomia. Known by some as a vodcast, the services handle both audio and video feeds. As well as public broadcasting made possible by Participatory Culture Foundation.

Other uses

Podcasting's initial appeal was to allow individuals to distribute their own "radio shows," but the system is increasingly used for other reasons, including:

  • A way for people and organizations to avoid regulatory bodies, like the British Ofcom, that would not allow a program to be broadcast in traditional media.
  • A way for news organizations to distribute audio as an addition to their existing text (or mostly text) news products. For example, Wikinews began to podcast its News Briefs in 2005.
  • Education. Musselburgh Grammar School, Scotland began podcasting foreign language audio revision and homework, possibly becoming the first school in Europe to launch a regular podcast. [27]. Some of the early classroom podcasts from America include The Room 208 Podcast from Wells, Maine, Radio WillowWeb from Omaha, Nebraska, and Room 613 Talk from Columbia, CT. The online encyclopedia Wikipedia has begun podcasting encyclopedia articles.
  • Politics. In the U.S., both major political parties have various podcasts, as do several politicians.
  • Religion. Podcasting (or in this context, Godcasting) has been used by many religious groups [28]. Many churches produce podcasts of talks and sermons. ''Disciples with Microphones'' provides podcasts relating to the Catholic church [29].
  • Unofficial audio tours of museums (musecast) [30].
  • Official Cultural Historic Audio Tour of cities ([audisseyguides]).
  • Communication from space. On 7 August 2005. American astronaut Steve Robinson claimed the first podcast from space during the Space Shuttle Discovery mission STS-114 - although there was no subscription feed, merely an audio file that required manual downloading. (transcript & audio).
  • Television Commentary. Battlestar Galactica writer and executive producer Ronald D. Moore creates commentary podcasts for each new episode of Battlestar Galactica (download audio commentary). Other television shows have since followed suit.
  • Conference and meeting alerts. Podcasts can be packaged to alert attendees to agendas, hosted roundtables and daily feedback. See Grass Shack
  • Advocacy. The 5,500 locked out staff (editors, journalists, technicians, hosts, etc.) of the Canadian Broadcasting Corporation were podcasting news and other programming during August and September of 2005.
  • Youth Media. Podcasting has become a way for youth media organizations, such as Youth Radio (Youth Radio site), to bring youth perspectives to a wider audience.
  • Newspapers. Newspapers use podcasts to brodcast audio content from print interviews and drive traffic to their websites. The San Franciso Chronicle is believed to be the first major daily newspaper to start podcasting using an external website (http://sfchroniclebiz.blogspot.com) in Feb 2005. Hong Kong's South China Morning Post was the first to use its own website and the first in Asia (http://podcasting.scmp.com), having launched on April 19, 2005.
  • The Society of Critical Care Medicine has a podcast used to update clinicians with summaries of important articles, as well as interviews. See SCCM Podcasts
  • In the second half of 2005, a Communication Studies course at the University of Western Australia (iGeneration: Digital Communication and Participatory Culture) used student-created podcasts as the main assessment item.

Podcasting and Music Royalties

From the beginning, the use of licensed music in podcasts has been a delicate legal issue. As was originally the case with streaming Internet radio, this new and infinitely more archivable form of media content would need to comply with as-yet unwritten rules.

Regular radio-based podcasts

Regular radio broadcasters' podcasts (and MP3 file downloads without subscription feeds) have run into complications regarding royalties for incidental music on "talk" broadcasts, even when identical programs are "streamed." The broadcasters apparently believe companies that license the music will challenge its use in easily downloaded MP3 files, while "streaming" is closer to a broadcasting model.

For example, when popular U.S. conservative commentator Rush Limbaugh began offering "podcasts" early in 2005, his employer, Premiere Radio Networks, tightened its editing of intro and bumper music, which it previously had allowed on other MP3 files. One effect was to render some of Premiere broadcaster Glenn Beck's podcasts difficult to follow. He would appear to stop mid-sentence and restart in a different thought, because of cuts required to remove royalty-protected music.

Future Licensing Issues

The US Congress is studying possible reforms to the Telecommunications Act of 1996, which may in the future affect broadband and Internet services.

See also

Notes and references

  1. ^ Technology writer Doc Searls had proposed "Personal Option Digital" in September, 2004. The "Personal On-Demand" interpretation (with that capitalization) had been in international circulation as early as October 2004. In July 2005, Microsoft blogger Robert Scoble used that same version when countering reports that his company was pushing the word "blogcasting" to avoid mentioning an Apple product. Scoble, Robert, 2005. "Blogger gives incorrect data about podcasting at Microsoft."
  2. ^ Louis, Tristan, 13 October 2000. Suggestion for RSS 0.92 specification
  3. ^ Winer, Dave, 25 December 2000 RSS 0.92 Specification
  4. ^ Winer, Dave, 27 December 2000 Scripting News: Heads-up, I'm working on new features for RSS that build on 0.91. Calling it 0.92...
  5. ^ Winer, Dave, 31 October 2000 Virtual Bandwidth; and 11 January 2001 Payloads for RSS
  6. ^ Winer, Dave, 11 January 2001 Scripting News: Tonight's song on the Grateful Dead audio weblog is Truckin...
  7. ^ Ed Radio
  8. ^ Marks, Kevin. October 2003 video excerpt of Marks's demo (MPEG-4) Real stream of full Audioblogging session (start 48 minutes in) blog post
  9. ^ Hammersley, Ben. 2004. "Audible revolution." In The Guardian, Thu, 12 February 2004.
  10. ^ Gregoire, Dannie J. 2004. "How to handle getting past episodes?" In the ipodder-dev mailing list, Thu, 16 September 2004.
  11. ^ Torrone, Phillip. 2004. "How-To: Podcasting." In Engadget, 5 October 2004.
  12. ^ Searls, Doc. 28 September 2004. Doc Searls' IT Garage, "DIY Radio with PODcasting."
  13. ^ Farivar, Cyrus. 28 October 2004. The New York Times, "New Food for IPods: Audio by Subscription."
  14. ^ Acohido, Byron. 9 February 2005. USA Today, "Radio to the MP3 degree: Podcasting."
  15. ^ Della Cava, Marco R. 9 February 2005. USA Today, "Podcasting: It's all over the dial."
  16. ^ Edwards, John, 2005-05-22. One America Podcast
  17. ^ White House, 2005. White House Radio Addresses
  18. ^ Crofts, Sheri, et al. Podcasting: A new technology in search of viable business models. First Monday, September 2005.
  19. ^ Web Talk Radio, 2004-09-15. "WebTalk Launches New Website."
  20. ^ BBC Press Office, 2005. "BBC podcasting sparks Fighting Talk."
  21. ^ Newitz, Annalee. 2005. "Adam Curry is a self-promoting Glory Hound!." In Wired Magazine. See also: CBC Podcasting page.
  22. ^ BBC Press Office, 2005. "BBC to podcast up to 20 more programmes including Today and Radio 1 speech highlights."
  23. ^ ABC Radio National podcasts.
  24. ^ Apple – iTunes
  25. ^ iTunes Podcast Subscriptions Top One Million
  26. ^ Musselburgh Grammar School Podcast
  27. ^ Heinen, Tom. 2005. "Podcasting becomes another pulpit." In JS Online, 11 June 2005.
  28. ^ Disciples with Microphones
  29. ^ Kennedy, Randy. 2005. "With Irreverence and an iPod, Recreating the Museum Tour." In The New York Times, May 28 2005.
  30. ^ BBC Collective, 2005. Podcasting for beginners
  31. ^ Dear Listener -- Podcasting Classics
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Finding podcasts

As of December, 2, 2005, the following links point to a list of podcast search engines:

  • CastWiki A list of podcast search engines and directories
  • Digital Podcast A list of podcast search engines and directories
  • EveryPodcast.com An unmoderated list of podcasts
  • Feedzie.com Search for thousands of podcasts and their hundreds of thousands of episodes
  • fluctu8 Web based podcast directory / aggregator where you can search for, listen to, and manage podcasts.
  • KedoraTV is a program guide with podcasts and vidcasts.
  • My Podcast Center A continually growing source of podcast directories
  • Odeo A directory of podcasts, and web-based tools for creating podcasts.
  • Podcast 411 A list of podcast Directories and search engines with links to add your podcast.
  • Podcast Alley Comprehensive podcast directory, information source and bulletin board.
  • PodcastDirectory.com Podcast directory of audio and video podcasts.
  • Podcasting News Podcast news and information.
  • Podcast Media Source of podcasts
  • PodcastPickle.com The first podcast/vidcast community on the Internet, with a large podcast & vidcast directory.
  • PodcastPUP A podcasting directory that brings together all genres of media!.
  • PodNova Podcast directory (audio/video) where you can subscribe, listen and watch.

Open-Source Podcast receivers

  • Juice (formerly known as iPodder Lemon) GPL free Podcast receiver for Windows, Mac OS X, and Linux.
  • amaroK GPL is able to play podcasts (KDE/QT)
  • CastPodder (formerly known as iPodder Linux version) GPL free Podcast receiver for Linux.
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