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 Apple
iTunes UK
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iTunes is a digital media player application,
introduced by Apple on January 10, 2001 at
Macworld Expo in San Francisco, for playing and
organizing digital music and video files. The
program is also an interface to manage the
contents on Apple's popular iPod digital media
players. Additionally, iTunes can connect to the
iTunes Store in order to download purchased
digital music, music videos, television shows,
iPod games and feature length films.
It was originally developed by Jeff Robbin and
Bill Kincaid as an MP3 player called SoundJam MP
and released by Casady & Greene in 1999. It was
purchased by Apple in 2000, given a new user
interface and the ability to burn CDs, had its
recording feature and skin support removed, and
released as iTunes. Originally a Mac OS 9-only
application, Mac OS X support was added with the
release of version 2 nine months later and Mac OS
9 support was dropped with the release of version
3. In October 2003, with the release of iTunes
4.1, Apple added support for Windows 2000 and
Windows XP.
Apple also developed iTunes branded software which
runs on mobile phones such as the Motorola ROKR,
Motorola RAZR and Motorola SLVR (although as of
October 2006 this version hasn't been updated to
play songs purchased with iTunes 7.0).
It is available as a free download from Apple's
website, is bundled with all Macintosh computers
and some iPods and supplied with Mac OS X. It is
also offered as part of Apple's iLife suite of
multimedia applications.
Features
Users are able to organize their music into
playlists within one or more libraries, edit file
information, record compact discs, copy files to a
digital audio player, purchase music and videos
through its built-in music store, download
podcasts, back up songs onto a CD or DVD, run a
visualizer to display graphical effects in time to
the music, and encode music into a number of
different audio formats.
Playlists
In addition to static playlist support, iTunes
supports 'Smart playlists'. Smart playlists are
playlists that can be set to automatically update
(live updating), (like a database query) based on
a customized list of selection criteria. Different
criteria can be entered to control many aspects of
the playlist.
Playlists can also be published by a user of
iTunes with his or her or preferences.
Playlists can be played randomly or sequentially.
The "randomness" of the shuffle algorithm can be
biased for or against playing multiple tracks from
the same album or artists in sequence (a new
feature in iTunes 5.0). Party Shuffle can also be
biased towards selecting tracks with a higher star
rating. With this bias enabled, each star rating
increases the preference for that particular song
about 4% over that of a one-star-less rated song.
Unrated songs are the least likely to be played.
Inter-star ratings are stored by iTunes, but only
affect this feature in the range of zero to one
star.
The Party Shuffle playlist is intended as a simple
DJing aid.By default, it selects tracks randomly
from other playlists or the library; users can
override the automatic selections by deleting
tracks (iTunes will choose new ones to replace
them) or by adding their own via drag-and-drop or
contextual menu. This allows a mixture of both
preselected and random tracks in the same meta-playlist.
The playlist Party Shuffle draws from can be
changed on the fly; this will cause all randomly
chosen tracks to disappear and be replaced.
Music library
iTunes keeps track of songs by creating a virtual
library, allowing users to access and edit a
song's attributes. These attributes, known as
metadata, are stored in two library files.
The first is a binary file called iTunes Library (iTunes
x Music Library in previous versions) that uses
its own music library format. This both caches
information such as artist and genre from the
audio format's tag capabilities (for example the
ID3 tag), and stores iTunes specific information
such as play count and rating. This is the only
one of the two files which iTunes reads.
The second file, called iTunes Music Library.xml,
is refreshed whenever information in iTunes is
changed. It uses an XML format, allowing
developers to easily write applications that can
access the library information (including play
count, last played date, and rating, which are not
standard fields in the ID3v2.3 format). Apple's
own iDVD, iMovie, and iPhoto, and Freshly Squeezed
Software's Rock Star are examples of applications
that access the library.
For MP3 files, iTunes writes tags in Unicode
ID3v2.2 by default, but converting them to ID3v2.3
and ID3v2.4 is possible via its "Advanced" >
"Convert ID3 Tags" toolbar menu. If both ID3v2.x
and ID3v1.x tags are in a file, iTunes ignores the
ID3v1.x tags.
AAC and Apple Lossless files support Unicode
metadata, stored in the MP4 container as so-called
"Atoms". Although iTunes can play OGG Vorbis or
FLAC if the required QuickTime plugins are
installed, it cannot add these files to the
library.
Printing
To compensate for the lack of a physical CD,
iTunes can print custom-made jewel case inserts as
well as song lists and album lists. After burning
a CD from a playlist, one can select that playlist
and, by clicking File > Print, bring up a dialogue
box with several print options. The user can
choose to print either a single album cover (for
purchased iTunes albums) or a compilation cover
(for user-created playlists). iTunes then
automatically sets up a template with art on one
side and track titles on the other.
iMix
An iMix is a user-created playlist published in
the iTunes Store. iMixes were first introduced in
iTunes version 4.5. Anyone can create an iMix free
of charge. iMixes are limited to 100 songs and
support both music downloaded from the music store
as well as music that has been imported from CDs
(provided it is available on the iTunes Store).
iMixes are public and searchable by any iTunes
user. Users may also rate any iMix using a
five-star system. iMixes are active for one year
from their original published date. Users can
publish their iTunes iMix to their blog, profile
page or website.
Internet radio
iTunes 1.0 came with support for the Kerbango
Internet radio tuner service, giving iTunes users
a selection of some of the more popular online
radio streams available. When Kerbango went out of
business in 2001, Apple created its own Web radio
service for use with iTunes 2.0 and later. As of
February 2006, the iTunes radio service features
around 300-400 distinct "radio stations" (with a
total of over 700 streams, allowing for multiple
bit rates), mostly in MP3 streaming format.
Programming covers many genres of music and talk,
including streams from online staples such as
Radio Paradise, radioio, RauteMusik, Digitally
Imported, Flashback Alternatives, and SomaFM as
well as terrestrial stations such as KKJZ, WFMU,
WMVY, and WRCT. iTunes also supports the .pls and
.m3u stream file formats used by Winamp, enabling
iTunes to access almost any stream using that
format.
Up until iTunes 7, Apple no longer promoted the
Internet radio feature, and no mention of it
appeared on the iTunes website. However, it
remains in the QuickTime 7.0.4 & iTunes EULA used
by iTunes 6.0.5.20. With iTunes 7, the "Radio"
item has reappeared as an optional source in the
preferences, along with its stations.
File format support
iTunes 7 can currently read, write, and convert
between MP3, AIFF, WAV, MPEG-4, AAC, and Apple
Lossless.
It can also play anything QuickTime can play (even
some video formats), including Protected AAC files
from the iTunes Store and Audible.com audio books.
In order to play other formats such as the Ogg-contained
Vorbis or Speex codecs, iTunes requires the Xiph
QuickTime Components to be installed. iTunes
currently will not play back HE-AAC/aacPlus audio
streams correctly. HE-AAC/aacPlus format files
will play back as 22 kHz AAC files (effectively
having no high end over 11 kHz). HE-AAC streaming
audio (which a number of Internet Radio stations
use) will not play back at all.
There has been some criticism of the quality of
Apple's MP3 encoder, with regards to variable bit
rate encoding. In a January 2004 double-blind
public listening test of six MP3 encoders encoding
at 128 kbit/s, conducted by Roberto Amorim, the
iTunes MP3 VBR encoder came last. The author has
later acknowledged that there were serious issues
with how iTunes was tested.
The Windows version of iTunes can automatically
convert unprotected WMA (including version 9)
files to other audio formats, but it does not
support direct playback or encoding of WMA format.
Sound processing
iTunes includes sound processing features, such as
equalization, "sound enhancement" ("sound
improvement" in some languages) and crossfade.
There is also a feature called "Sound Check" which
automatically adjusts the playback volume of all
songs to the same level. Like "sound enhancement",
this can be turned on in the 'Playback' section of
iTunes' preferences.
Music sharing
iTunes Library songs can be shared over a local
network using the closed, proprietary Digital
Audio Access Protocol (DAAP), created by Apple for
this purpose. DAAP relies on the Bonjour network
service discovery framework – Apple's
implementation of the Zeroconf open network
standard. The DAAP specification has not been
published by Apple, but the protocol has been
reverse-engineered and is now used to stream
playlists from non-Apple software (mainly on the
Linux platform).
DAAP allows shared lists of songs within the same
subnet to be automatically detected. When a song
is shared, iTunes can stream the song but won't
save it on the local hard drive, in order to
prevent unauthorized copying. Songs in Protected
AAC format can also be accessed but authentication
is required. A maximum of five users may connect
to a single user every 24 hours.
Originally with iTunes 4.0, users could freely
access shared music anywhere over the Internet, in
addition to one's own subnet, by specifying IP
addresses of remote shared song libraries. Apple
quickly removed this feature with version 4.0.1,
claiming that users were violating the End User
License Agreement.
With the release of iTunes 7.0, Apple changed
their implementation of DAAP slightly. This change
prevents third-party clients from connecting to a
remote iTunes repository, but iTunes will still
connect as a client to other iTunes servers and to
third-party servers. This difficulty will remain
until the changes are reverse engineered again or
Apple publishes specifications and the updates are
implemented in software.
Video
On May 9, 2005, video support was introduced to
iTunes with the release of iTunes 4.8. Users can
drag and drop movie clips from the computer into
the iTunes Library for cataloging and
organization. They can be viewed in a small frame
in the main iTunes display, in a separate window,
or fullscreen. Before version 7 provided separate
libraries for media types, videos were only
distinguished from audio in the Library by a small
icon resembling a TV screen and grouped with music
in the library, organized by the same musical
categories (such as "album" and "composer").
iTunes relies on Quicktime and is therefore
incompatible with some common video formats,
including WMV.
On October 12, 2005, Apple introduced iTunes 6.0,
which added support for purchasing and viewing of
video content from the iTunes Music Store. The
iTunes Music Store initially offered a selection
of several thousand Music Videos and five TV shows
including most notably the ABC network's Lost and
Desperate Housewives. Disney channels shows were
also offered (The Suite Life of Zack and Cody and
That's So Raven) 24 hours after airing as well as
episode packs from past seasons; since that time,
the collection has expanded with content from
numerous television networks. The iTunes Music
Store also gives the ability to view Apple's large
collection of movie trailers.
As of September 12, 2006, the newly-renamed iTunes
Store offers over 200 television shows for
download, including, most recently, additions from
Discovery Channel, Comedy Central, MTV, and FOX.
Additionally, a catalog of 75 feature-length
movies from Disney-owned studios was introduced.
The number of feature-length movies featured on
iTunes as of January 12, 2007 is 199.
As of December 2006, movies and TV shows are only
available to U.S. customers, with the only video
content available to non-U.S. customers being
music videos and Pixar's short films.
Video content available from the store used to be
encoded as 540 kbit/s Protected MPEG-4 video
(H.264) with an approximately 128 kbit/s AAC audio
track. Many videos and video podcasts currently
require the latest version of Quicktime, Quicktime
7, which is incompatible with older versions of
Mac OS (only v10.3.9 and later are supported).
Starting September 12, 2006, the resolution of
video content sold on the iTunes Store was
increased from 320x240 (QVGA) to 640x480 (VGA).
The higher resolution video content is encoded as
1.5 Mbit/s Protected MPEG-4 video (H.264) with an
approximately 128 kbit/s AAC audio track. |
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