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iTunesRSS

This is the iTunes RSS page and is devoted to the study and commenting of the Apple iTunes RSS specification and practicle applications of that specification.

RSS Feed Specification

The iTunes RSS specification is based on RSS 2.0. As such an understanding of RSS 2.0 is helpful to fully understand the iTunes RSS format.

RSS2.0

Information regarding RSS 2.0 can be found here:
http://www.rssboard.org/rss-specification
http://blogs.law.harvard.edu/tech/rss
It is worth noting that RSS has been rapidly changing over the past couple of years and is highly fragmented. As such some trial and error are required to implemement an RSS feed or aggrigator.

Minimum Data Elements w/ Mapping for RSS 2.0

I'm going out on a limb and saying that if TikiWiki supports all of the required elements for the iTunes application, then most all aggregators will work with TikiWiki. Since iTunes is so pervasive in podcasting, I can't imagine an aggregator that will not accept an iTunes compatible feed. I'll save this section for a future exercise when my assumption turns out to be wrong. Below are the minimums from the RSS 2.0 definition because Apple defines its own requirements as RSS 2.0 plus extensions:

Required Channel Elements
titleThe name of the channel. It's how people refer to your service. If you have an HTML website that contains the same information as your RSS file, the title of your channel should be the same as the title of your website.
linkThe URL to the HTML website corresponding to the channel
descriptionPhrase or sentence describing the channel
<item>A channel may contain any number of <item>s. This element is the base container for each media podcast and descriptive text

Required Item Elements
One of the following
titleThe title of the item
descriptionThe item synopsis

iTunes

http://www.apple.com/itunes/podcasts/techspecs.html
The actual iTunes aggregator will work with the minimum set of tags specified by Apple; effectively supporting the music store requires more.

The iTunes Music Store might work with the minimum number of attributes, but it is most likely that users will find that they need more tag support, and local data definition, to have an effective presence on the iTunes Music Store. This is noted in the technical specification:
Note that the additional tags are not required (except to be eligible for featured placement on the iTunes Podcast page), but are recommended where needed in order to provide the best possible user experience


Enclosure Naming Limitation

The media link in the <enclosure> tag must have an iTunes supported file extension. This has a large impact on how TikiWiki works since file gallery entries are references to a .php file. The rewriting rules of the web server can be used to support this iTunes limitation. Below is a quote from the iTunes technical specification:
The URL before the GET-style form values (before the first ?) must end in a media file extension (e.g. mp3). To work around this, the feed provider can alter their URL from this

http://www.podcaster.com/load.php?f=&Wipeout.php

to this:

http://www.podcaster.com/load.mp3?f=&Wipeout.mp3

Notice how it says load.mp3 instead of load.php. It should be possible to accomplish this via various means, such as web server rewrites. iTunes looks at the extension of the path part of the url, i.e. the part before the"?".


It has been confirmed experimentally that only the portion before the ? is considered by iTunes even though the example in the specification shows rewriting of both the .php before the ? and after the ?.

This is an unnecessary limitation in the truest form because the <enclosure> tag has a mandatory type attribute that defines the media type. It is not clear if the media extension (e.g. .mp3) must match the actual media encoding. One option is to just always put .mp3 on the URL and set the type attribute to the correct media encoding. Otherwise a web server rewriting rule can be assigned for every iTunes supported media type file extension.

Media Encodings

Supported Media Types
FileType
.mp3audio/mpeg
.m4aaudio/x-m4a
.movvideo/mpeg
.mp4video/mp4
.m4vvideo/x-m4v
.movvideo/quicktime
.pdfapplication/pdf

Supported Encoding Formats
H.264 video
File formats.m4v, .mp4, and .mov
VideoUp to 768 kbps, 320 x 240, 30 frames per second (fps), Baseline Profile up to Level 1.3
AudioAAC-LC up to 160 kbps, 48 Khz, stereo audio
MPEG-4 video
File formats.m4v, .mp4, and .mov
VideoUp to 2.5 mbps, 480 x 480, 30 fps, Simple Profile
AudioAAC-LC up to 160 kbps, 48 Khz, stereo audio


RSS Tag Usage

This information is from the spec. It may or may not reflect the actual iTunes implementation.

XML TagChannelItemWhere content appears in iTunes
<title>YYName column
<link>Y website link and arrow in Name column
<copyright>Y not visible
<pubDate>Y Release Date column
<itunes:author>YYArtist column
<itunes:block>YYprevent an episode or podcast from appearing
<itunes:category>Y Category column and in iTunes Music Store Browse
<itunes:image>Y same location as album art
<itunes:duration>Y Time column
<itunes:explicit>YYparental advisory graphic in Name column
<itunes:keywords>YYnot visible but can be searched
<itunes:new-feed-url>Y not visible, used to inform iTunes of new feed URL location
<itunes:owner>Y not visible, used for contact only
<itunes:subtitle>YYDescription column
<itunes:summary>YYwhen the "circled i" in Description column is clicked


Contributors to this page: michael .
Page last modified on Sunday 17 of September, 2006 11:53:20 CDT by michael.