Podcasting

What is Podcasting?

Podcasts are digital media files (most often audio, but they can be video as well), which are produced in a series. You can subscribe to a series of files, or podcast, by using a piece of software called a podcatcher. Once you subscribe, your podcatcher periodically checks to see if any new files have been published, and if so, automatically downloads them onto your computer or portable music player for you to listen to or watch, whenever you wish.

Podcasting is delivering audio content to iPods and other portable media players on demand, so that it can be listened to at the user's convenience. The main benefit of podcasting is that listeners can sync content to their media player and take it with them to listen whenever they want to. Because podcasts are typically saved in MP3 format, they can also be listened to on nearly any computer.

The term podcasting was popularized by media entrepeneuar and former MTV VJ Adam Curry. Curry created an Applescript application that automated the process of downloading and syncing audio files to iPods.

Curry's application built on the work of programmer Dave Winer, a pioneer in both the world of web logs and XML development. Winer wrote the RSS 2.0 specification, which is used to deliver information about podcasts. RSS is an XML format that is used to define channels of information that contain elements, which are typically stories or web log entries.

RSS files are often used as a standardized way of publishing meta information about content. For example, web logs are typically user's thoughts about news stories or other web content.

RSS 2.0 supports enclosures, which are URL references to web content. This makes it possible to use RSS files to provide information about web content in a standard XML-based format. Podcasts are simply the application of RSS enclosures to audio files.

Podcasting in 4 Steps

1. Publishers create audio content, and post it to a web server, typically in MP3 format.
2. They publish an RSS file (newsfeed)  that contains RSS news items that reference the audio content. Each RSS item provides meta information about an audio file, such as the file's name and description, and contains an RSS enclosure with the URL of the audio file.
3. End-users regularly check for new versions of the newsfeed, using an application like iPodder. When a new version is found, iPodder reads through it, identifies the audio file URLs, downloads them and syncs them to a media player.
4. Users listen to the "podcasted" audio file when it is convenient.

Podcasting has been described as TiVo for Internet audio, because it lets users save content digitally, and replay it at their convenience. This comparison, though, only addresses the idea of time-shifting, and not the idea that podcasting lowers barriers to entry, creates an alternate distribution model for audio content or that it lets publishers extend the reach of Internet content to times when people aren't even connected.

Podcasting can be used for publishing any type of audio, and some developers are exploring the idea of using the same techniques to publish video and other types of content.

Podcasting is spreading quickly because of the rapid adoption of MP3 players, and the desire of owners to have fresh content.