Podcast

Un article de Vev.

A podcast is a collection of digital media files which is distributed over the Internet using syndication feeds for playback on portable media players and personal computers. The term, like "radio", can refer either to the content itself or to the method by which it is syndicated; the latter is also termed podcasting. The host or author of a podcast is often called a podcaster.

The term "podcast" is a portmanteau of the words "iPod" and "broadcast",<ref>http://www.oup.com/elt/catalogue/teachersites/oald7/wotm/wotm_archive/podcast?cc=global</ref> the Apple iPod being the brand of portable media player for which the first podcasting scripts were developed (see history of podcasting). These scripts allow podcasts to be automatically transferred to a mobile device after they are downloaded.<ref>http://radio.weblogs.com/0001014/2003/10/12.html#a4604</ref>

Though podcasters' web sites may also offer direct download or streaming of their content, a podcast is distinguished from other digital media formats by its ability to be syndicated, subscribed to, and downloaded automatically when new content is added, using an aggregator or feed reader capable of reading feed formats such as RSS or Atom.

Sommaire

1 Trends and development
- 1.1 Naming and intellectual property
2 Mechanics
3 Receiving and using podcasts
- 3.1 Managing podcasts on an iPod
- 3.2 Example
4 Other uses
5 Trademarks
6 Other
7 See also
- 7.1 Syndication protocols
8 References
9 External links

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Trends and development

Main article: History of podcasting

The evolution and history of podcasting has revealed some noteworthy trends and developments that have arisen because of the nature, methods and terminology associated with podcasting.

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Naming and intellectual property

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Mechanics

Modèle:Original research Podcasting is an automatic mechanism whereby multimedia computer files are transferred from a server to a client, which pulls down XML files containing the Internet addresses of the media files. In general, these files contain audio or video, but also could be images, text, PDF, or any file type.

The content provider begins by making a file (for example, an MP3 audio file) available on the Internet through some known Uniform Resource Identifier. This is usually done by posting the file on a webserver; however, BitTorrent trackers also have been used. The files may be available to the general public or may only be available to certain users.

The content provider then announces the existence of that file by referencing it in another file known as the feed. The feed is a list of the URLs by which episodes of the podcast may be accessed. This list is usually published in RSS format (although Atom can also be used), which provides other information, such as publish date, titles, and accompanying text descriptions of the series and each of its episodes. The feed may contain entries for all episodes in a series, but is typically limited to a short list of the most recent episodes, as is the case with many news feeds. Standard podcasts consist of a feed from one author. More recently, multiple authors have been able to contribute episodes to a single podcast feed using concepts such as social podcasting.

The content provider posts the feed on a webserver. The location at which the feed is posted is expected to be permanent. This location is known as the "feed URL" or "feed URI". The content provider makes this feed known to the intended audience.

A podcast specific aggregator is usually an always-on program which starts when the computer is started and runs in the background. It works exactly like any aggregator which checks each feed at a specified interval, such as every two hours. If the feed data has substantially changed from when it was previously checked (or if the feed was just added to the application's list), the program determines the location of the most recent item and automatically downloads it. The downloaded episodes can then be played, replayed, or archived as with any other computer file. Many applications also automatically transfer the newly downloaded episodes available to a user's portable media player, which is connected to the PC running the aggregator, perhaps via a USB cable.

The publish/subscribe model of podcasting is a version of push technology, in that the information provider chooses which files to offer in a feed and the subscriber chooses among available feed channels. While the user is not "pulling" individual files from the Web, there is a strong "pull" aspect in that the receiver is free to subscribe to (or unsubscribe from) a vast array of channels. Earlier Internet "push" services (e.g., PointCast) allowed a much more limited selection of content.

In March 2006 it was reported that 80% of podcast "episodes" are "consumed" on the PC onto which they are downloaded, i.e. they are never actually transferred to a portable player, or are deleted from the PC without being listened to.<ref>Dixon, Colin; Greeson, Michael. "Recasting the Concept of Podcasting: Part I." TDG Research. March 23 2006. Accessed October 8 2006.</ref> To conserve bandwidth, users may opt to search for content using an online podcast directory. Some directories allow people to listen online and become familiar with the content provided from an RSS feed before deciding to subscribe. For most broadband users, bandwidth is generally not a major consideration.

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Receiving and using podcasts

To make full use of podcasts' syndication features appropriate software, often referred to as a podcatching client. The most dominant podcatching client is Apple's iTunes player. However, there are other alternatives, including Juice (multiplatform) and Doppler (Windows). Some established audio players, such as AmaroK, Winamp and Mediamonkey also offer (sometimes limited) podcatching functionality.

Podcast listeners can listen in one of two ways: through a specialized hardware device called an MP3 player or on a computer using media player software.

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Managing podcasts on an iPod

Image:Podcasr updating.JPG

Only the latest unlistened podcasts are put in this playlist. The user can thus ensure that all news programs are new and current and also unlistened. This playlist is synchronized regularly with the iPod

iTunes offers the ability to create "Smart Playlists" which can be used to control which podcasts are in the playlist using multiple criteria such as date, number of times listened, type, etc. It is also possible to set up iTunes so that only certain playlists will be synced with the iPod. By using a combination of the two techniques it is possible to control exactly which music and/or podcasts will be transferred to the iPod. The illustration to the right shows one such "Smart playlist" which ensures that only the latest unlistened podcasts will be in the smart playlist. Any podcast which is more that two weeks old is not included, nor is any podcast that the iPod user has already listened to. This smart playlist is synced with the iPod every time the iPod is plugged into the PC, ensuring that the user does not have to listen to the same show more than once. Once a podcast has been listened to, it will be removed from this list as soon as the iPod is synced with the PC. There are many criteria which can control what goes in a smart playlist, such as "name," "artist," "category," "grouping," "kind," "last played," "play count," "rating," "last skipped," and "playlist" and these can be combined with functions such as "equals," "is greater than," "is less than," "contains," "is true," "is false," "is," "is not," "does not contain," "starts with," "ends with," "is in the range," "is before," and "is after". As a result, it is possible to control exactly which podcasts are transferred to the iPod.

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Example

For example, a user may only want news programs less than 24 hours old, unlistened science programs less than one month old, and all Spanish lessons that he/she has yet listened to less than three times. By using smart playlists, she/he can ensure that these rules will be followed. The user would set up four smart playlists. The first smart playlist containing news podcasts downloaded in the last 24 hours, the second containing the science podcasts which are unlistened and less than one month old, and a third smart playlist containing Spanish lessons which have been listened less than three times, and a fourth smart playlist which contains the contents of the first three. The fourth smart playlist is the one which would be synced with the iPod. Obviously the fourth playlist may contain many other play lists as well as the ones described above.

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Other uses

Main article: Uses of podcasting

Podcasting's initial appeal was to allow individuals to distribute their own radio-style shows, but the system quickly became used in a wide variety of other ways, including distribution of school lessons,<ref>http://www.map100.com/mapinteresting.php/podcasts-increasing-in-popularity/</ref> official and unofficial audio tours of museums, conference meeting alerts and updates, and by police departments to distribute public safety messages.

Podcasting is becoming increasingly popular in education. Podcasts enable students and teachers to share information with anyone at anytime. An absent student can download the podcast of the recorded lesson. It can be a tool for teachers or administrators to communicate curriculum, assignments and other information with parents and the community. Teachers can record book discussions, vocabulary or foreign language lessons, international pen pal letters, music performance, interviews, and debates. Podcasting can be a publishing tool for student oral presentations. Video podcasts can be used in all these ways as well.

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Trademarks

On February 5, 2005, Shae Spencer Management LLC of Fairport, New York filed a trademark application to register PODCAST for an 'online prerecorded radio program over the internet'.<ref>PTO Letters of Protest: The "PODCAST" Paradigm</ref> On September 9, 2005, the United States Patent and Trademark Office rejected the application. The rejection notice cited Wikipedia's podcast entry as describing the history of the term.<ref>Podcast trademark rejection cites Wikipedia</ref>

As of September 19, 2005, known trademarks that capitalize on podcast include: Podcast Realty, GuidePod, PodGizmo, Pod-Casting, MyPod, Podvertiser, ePodcast, PodCabin, Podcaster, PodShop, PodKitchen, Podgram, GodPod and Podcast.<ref>Podcast Trademark Gold Rush</ref>

As of February 2007, there have been 24 attempts to register trademarks containing the word "PODCAST" in United States, but only "PODCAST READY" from Podcast Ready, Inc. was approved.<ref>List of US podcast trademarks</ref>

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Other

In November of 2004, Pittsburgh-based podcast hosting service Liberated Syndication was launched. The company, also known as Libsyn, was one of the first podcast hosting companies on the scene.

In 2005, it was reported that Adam Curry had anonymously edited the podcasting entry on Wikipedia to remove credits from other people and to inflate his role in its creation.<ref>Adam Curry Caught in Sticky Wiki</ref> The business model of Curry's podcasting network Podshow has since been criticised by many in the industry, and has been accused of exploitative practices in its dealings with independent podcasters.

On September 26, 2006, it was reported that Apple Computer started to crack down on businesses using the word 'pod' in product and company names. Apple sent a cease-and-desist order that week to Podcast Ready, which markets an application known as myPodder.<ref>http://www.podcastready.com/info.php?section=8&page=41</ref> Lawyers for Apple contended that the term "pod" has been used by the public to refer to Apple's music player so extensively that it falls under Apple's trademark protection.<ref>Apple cracks down on use of the word 'pod'</ref> It was speculated that such activity was part of a bigger campaign for Apple to expand the scope of its existing iPod trademark, which included trademarking "IPODCAST," "IPOD Socks," "POD."<ref>Podcast Trademark Controversy [Updated]</ref> On November 16, 2006, Apple Trademark Department returned a letter claiming Apple does not object to third party usage of "podcast" to refer to podcasting services and that Apple does not license the term.<ref>Apple letter.</ref>