播客，即英文的Podcast或Podcasting，这个词来源自苹果电脑的"iPod"与"广播"(broadcast)的合成词，其指的是一种在互 联网上发布文件并允许用户订阅feed以自动接收新文件的方法，或用此方法来制作的电台节目。这种新方法在2004年下半年开始在互联网上流行以用于发布 音频文件。
播客与其他音频内容传送的区别在于其订阅模式，它使用RSS 2.0文件格式传送信息。该技术允许个人进行创建与发布，这种新的传播方式使得人人可以说出他们想说的话。
订阅播客节目可以使用相应的播客软件。这种软件可以定期检查并下载新内容，并与用户的便携式音乐播放器同步内容。播客并不强求使用iPod或 iTunes; 任何数字音频播放器或拥有适当软件的电脑都可以播放播客节目。相同的技术亦可用来传送视频文件，在2005年，已经有一些播客软件可以像播放音频一样播放 视频了。
Podcasting is a means of distributing audio and video programs via the Internet that lets users subscribe to a number of files, also known as "feeds", and then hear or view the material at the time that they choose. A feed is usually in the MP3 audio format.
Podcasting became popular in late 2004 with the spread of free software that enabled automatic downloading of audio MP3 files onto computers and mobile MP3 players.
"Podcasting" is distinct from other types of online media delivery because of its subscription model, rather than one-time delivery. A series of files are delivered because subscribers want to get the information regularly.
Subscriptions use a "feed" (such as RSS or Atom) to deliver the enclosed files. Podcasting enables independent producers to create self-published, syndicated "radio shows," and gives broadcast radio or television programs a new distribution method. Listeners may subscribe to feeds using "podcatching" software (a type of aggregator), which periodically checks for and downloads new content automatically.
The word "Podcast" is often incorrectly used to describe any Web link to a media-player-compatible audio file. Some radio personalities post MP3 versions of their shows and call them podcasts even though they offer no subscription feed.
Most podcatching software facilitates copying podcasts to portable music players. Any digital audio player or computer with audio-playing software can play podcasts. From the earliest RSS-enclosure tests in 2000-2001, feeds have been used to deliver video files as well as audio. By 2005 some aggregators and mobile devices could receive and play video, but the "podcast" name remained most associated with audio.
"Podcasting" is a portmanteau that combines the words "broadcasting" and "iPod." The term can be misleading since neither podcasting nor listening to podcasts requires an iPod or any portable player, and no broadcasting is involved.
Aware of that misleading association from the beginning, some writers have suggested alternative names or reinterpretations of the letters "p-o-d", without winning much of a following.[1] One little-used alternative is "blogcasting", which implies content based on, or similar in format to, blogs. Another is "audioblogging."
History
Initial development
By 2003, web radio had existed for a decade, digital audio players had been on the market for several years, blogs and broadcasters frequently published MP3 audio online, and RSS file formats were widely used for summarizing or syndicating Web content. In 2001, UserLand founder and RSS evangelist Dave Winer responded to requests from customers Adam Curry[2] and Tristan Louis[3] for a way to deliver video or audio with their RSS feeds. Winer added a specific enclosure element to what was then his company's RSS specification, then to Radio Userland, a blogging system incorporating both a feed-generator and aggregator.[4] (Ironically, the rival RDF Site Summary syndication format already supported media resources implicitly, although applications rarely took advantage of the feature.)
In June 2003, Stephen Downes demonstrated aggregation and syndication of audio files using RSS in his Ed Radio application [5]. 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 2003, Winer created an RSS-with-enclosures feed for his Harvard Berkman Center colleague Christopher Lydon, a former newspaper and television journalist and NPR radio talk show host [6]. For several months Lydon had been linking full-length MP3 interviews to his Berkman weblog, which focused on blogging and coverage of the 2004 U.S. presidential campaigns. At the first Harvard BloggerCon conference, October 4-5, 2003, Kevin Marks demonstrated a script to download RSS enclosures to iTunes and synchronise them onto an iPod[7], something Adam Curry had been doing with Radio Userland and Applescript. Listening to Lydon's interviews on an iPod helped inspire Adam Curry to create a feed he called "syncpod," which was used for testing by Marks, Werner Vogels and other developers at the conference, some of whom became involved in open source iPodder development projects.
Curry's and Winer's podcasts, including several months of collaboration they called "Trade Secrets," spread interest in podcasting among other widely-read bloggers. Amateur blogs and open source developers continued as important factors in the popularization of podcasting before and after professional broadcasters and entrepreneurs with business plans adopted the form.
Possibly the first use of the term podcasting was as a synonym for audioblogging or weblog-based amateur radio in an article by Ben Hammersley in The Guardian on February 12, 2004 [8]. In September of that year, Dannie Gregoire used the term to describe the automatic download and synchronization idea that Curry had developed [9]. Gregoire had also registered multiple domain names associated with podcasting. That usage was discovered and reported on by Curry and Dave Slusher of the Evil Genius Chronicles website.
By October 2004, detailed how-to podcast articles[10] had begun to appear online. In November 2004, liberated syndication libsyn launched what was apparently the first Podcast Service Provider, providing storage, bandwidth, and RSS creation tools.
Precursor
Independently 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 proposed 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. "A year from now," he wrote, "it will pull up hundreds of thousands, or perhaps even millions." [11] (As of November 05, 2005 Google reports 90,100,000 for podcast)
Searls kept track of the search results in his blog through the next month. 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. His prediction of "perhaps millions" in a year proved to be conservative. After only nine months, a Google search for "podcasts" produced more than 10 million hits, and as of September 2005, the same search produces 61 million hits.
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. [12] USA Today told its readers about these "free amateur chatfests" the following February [13] [14], 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 No. 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 [15]. (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[16], 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, [17] and venture capital flowing to influential content providers.
The growing popularity produced specialties, including the "podsafe" category, which refers to a track that is legal for use on a podcast, usually because the band or artist is not signed to a major label and they (or their label) has given consent for their work to be redistributed via podcast or the recording was made under the Creative Commons license. However, the mere fact that an artist is not signed to a major label does not automatically mean that they have given consent for their work to be podcast. See also Copyright.
At podsafe sites artists can submit podsafe tracks and podcasters can sign up to get music for their shows.
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.
Adoption 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[18] 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[19]. January 2005 also saw CBC begin a trial with its weekly national technology column /Nerd[20]. 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 programmes, including music radio[21] and in the same month Australia's ABC launched a podcasting trial across several of its national stations[22].
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 California 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.
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.
When it added a podcast-subscription feature to its June 28, 2005, release of iTunes 4.9[23], 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.[24]
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. [25]. 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 [26]. Many churches produce podcasts of talks and sermons. Disciples with Microphones provides podcasts relating to the Catholic church [27].
* Unofficial audio tours of museums (musecast) [28].
* 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[[29]] for each new episode of Battlestar Galactica. 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 [[30]]
* 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 [31], 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 at [32] used to update clinicians with summaries of important articles, as well as interviews.
* 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.
Talk Shows and Music Royalties
Terrestrial 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
