Developed by Apple Inc.
Latest stable version 8.1.1.10 / April 8, 2009
[Edit this paragraph] Operating system
Mac OS
iTunes is a digital media player application launched by Apple Computer at the Macworld Expo in San Francisco on January 10, 2001. It is used to play and manage digital music and video files. The program is also an interface for managing content on Apple's popular iPod digital media player. In addition, iTunes can connect to the iTunes Store (assuming an Internet connection is established) to download purchased digital music, music videos, TV shows, iPod games, various podcasts, and standard feature films.
It was originally developed by Jeff Robbin and Bill Kincaid as an MP3 player program called SoundJam MP and published by Casady & Greene in 1999. Purchased by Apple Computer in 2000, it was given a new user interface and the ability to burn CDs, had its own recording capabilities, removed panel support, and was released as iTunes. Initially only available for Mac OS 9 applications, Mac OS X support was added nine months later with the release of version 2, and support for Mac OS 9 was discontinued 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. However, since the release of Microsoft's latest operating system, Windows Vista, Apple Computer has claimed that there have been several known compatibility issues with the iTunes software. Apple Computer will release a new version soon to correct the problem.
iTunes is available as a free download from the Apple Computer website, is included with all Macintosh computers and some iPods, and is available with Mac OS X. It is also available as part of Apple's iLife suite of multimedia applications.
[Edit this paragraph] function
Users can compose their music into playlists, edit file information, burn CDs, and copy files to Apple's MP3 player iPod, Purchase music through its built-in Music Store, download podcasts, back up songs to a CD or DVD, perform visualizations, perform live effects to match the music in real time, and encode music into many different audio formats.
[Edit this paragraph] Playlist
"Smart playlist" is a playlist that can be set to automatically update (online update), (like a database queue) based on A custom list selection criteria. Different standards can control different aspects of playlists.
Playlists can be played randomly or sequentially. A "random" shuffling algorithm can select different tracks from different tracks on an album or an artist for playback (a new feature in iTunes 5.0). Party Shuffle can also select tracks from higher-rated tracks to play.
Party Shuffle Playlist is used as a simple DJ assistant.
By default, it randomly selects music from your music library or other playlists; you can override its automatic selections by deleting songs (iTunes will select new songs to replace them), or by dragging and dropping songs. Add your own music instantly or from the right-click menu to achieve the same effect. This allows a playlist to contain both user-preselected and randomly selected music. Party shuffle playlists can be extracted on the fly; this causes all randomly selected music to be replaced while the playlist is playing.
[Edit this paragraph]Music Library
iTunes stores metadata about audio files in two files.
The first is a binary called iTunes Library (called iTunes x Music Library in previous versions), which uses its own proprietary music library format. It not only buffers information like artist and genre that are stored in the audio file's tag space (such as the ID3 tag), but also stores some iTunes-specific information like "play count" and "sample rate."
The second file, named iTunes Music Library.xml, is refreshed when the information in iTunes changes. It is in XML format, allowing developers to easily develop software such as Apple's iDVD, iMovie and iPhoto or Freshly Squeezed Software's Rock Star.[1] that can access its information.
This system prevents the manufacturer from taking possession of any changes to a track's metadata, except for the "play count", "last played" and "sample rate" metadata which are stored in the proprietary file , all other information becomes available through XML files.
[Edit this paragraph]COVER
To make up for the shortcomings of physical CDs, iTunes can print customized collector's edition inserts and song/album lists. After burning a CD from a playlist, the user can select the playlist and click File-Print to open a dialog box with print options. These users can choose to print a single album cover (a purchased iTunes album) or a group cover (a user-created list). iTunes can automatically set up a template that contains the album image on one side and the track titles on the other.
[Edit this paragraph]Internet Radio
iTunes 1.0 comes with support for the Kerbango Internet Radio service, providing iTunes users with another available stream of popular online radio stations choice. In 2001, Kerbango launched commercially, and Apple built its own online radio service for iTunes 2.0 and subsequent versions. As of July 2005, the iTunes radio service can support approximately 200 to 300 different "radio stations" (there are more than 400 multi-bitrate streaming media on the Internet), most of which are in the MP3 streaming format. Programming covers many types of music and talk, including major online broadcasters like Radio Paradise, DI.fm, SomaFM, and terrestrial stations such as KKJZ, WFMU and WMVY. iTunes also supports .pls and .m3u format files that can be played with Winamp. iTunes uses almost all streaming media formats.
Apple is no longer updating Internet Radio, and there is no mention of it on the iTunes website.
[Edit this paragraph] File format support
iTunes 7 can currently read, write and convert between MP3, AIFF, WAV, MPEG-4, AAC and Apple Lossless .
iTunes can also play anything QuickTime can play (even some video formats), including protected AAC files from the iTunes Store and Audible.com audiobooks. In order to play other formats, such as Vorbis or Speex encoding with Ogg, iTunes requires the Xiph QuickTime component installed. iTunes currently does not play HE-AAC/aacPlus audio streams correctly. HE-AAC/aacPlus format files can be played into 22 kHz AAC files (which actually do not exceed the 11 kHz treble limit). HE-AAC streaming audio (used by some Internet Radio channels) is completely unplayable.
There have been some reviews of the quality of Apple's MP3 encoder for encoding at variable bitrates. In a double-anonymous public listening test of six codecs that encoded MP3 at 128 kbit/s in January 2004, led by Roberto Amorim, the iTunes MP3 VBR codec ranked last. The leader later confirmed how iTunes had been tested to have serious problems. [1]
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 compiled WMA formats.
[Edit this paragraph] Sound processing
iTunes uses the computer's sound card to play music. iTune also includes audio processing functions called equalizing and "sound enhancer", which are also translated into "sound improver" in some languages.
[Edit this paragraph]Music sharing
Songs in the iTunes music library can be shared over a local network using Bonjour (formerly known as Rendezvous) - this is Apple's Zeroconf (Zero Configuration Required) open networking standard implementation. This technology allows songs in the same subnet segment to be automatically shared and detected. When a song is shared, iTunes will stream the song to another computer, but will not save it to prevent it from being copied. Songs that use copyright-protected AAC can also be accessed, but need to be authorized by the iTunes Music Store. A maximum of five users are allowed to connect every 24 hours.
In iTunes 4.0, users could freely access shared music through the Internet. In addition to through the same subnet, they could also share music data remotely by specifying those The IP address of the library. Apple Computer quickly removed this feature in version 4.0.1, stating that it violated the User License Agreement (EULA).
Music sharing uses the Digital Music Access Protocol (DAAP), which is a protocol created by Apple Computer specifically for sharing music. [2] DAAP has been unlocked by reverse engineering and is currently used by non-Apple software to share playlists.
[Edit this paragraph] Video
On May 9, 2005, iTunes 4.8 and iTunes video support were launched together. Users can pull video clips directly from the computer into the iTunes database Categorize and manage them in iTunes. Images can be viewed in small boxes in the main iTunes window, in separate windows, or in full screen. Video support in iTunes is less than perfect: although the images in the database are viewed by a TV or monitor The small icon is separate from the music, but is still placed together with the regular music files and classified by the same music categories (such as "Album" and "Composer"). iTunes is also incompatible with some major formats, including AVI and WMV.
On October 12, 2005, Apple launched iTunes 6.0, which can purchase and watch video content in the iTunes Music Store. At that time, the iTunes Music Store launched more than a thousand selected music videos and 5 The suite of TV shows, including ABC's "LOST" and "Desperate Housewives," will be available for purchase in the store 24 hours after the show airs, and will also include select shows from the previous season; the select shows at that time also included NBC Universal, USA Network, Sci-Fi Channel shows and Viacom, and later some Disney-owned networks' shows. The mall also released a selection of Apple movie trailers. The video formats purchased in the mall are 128 kbit/s Protected MPEG-4 video (H.264)1.
As of January 26, 2006, iTMS offers over 40 TV program downloads, including the latest additions Nickelodeon, Comedy Central and MTV's various series such as SpongeBob SquarePants, Dixieland and Punk\'d. Currently, many videos and Video Podcasts require the latest version of Quicktime (7), which is incompatible with older versions of MacOS (only v10.3.9 and later versions are supported).
As of July 4, 2006, the iTunes Music Store offers more than 150 television programs for download; including recently added programs from Discovery Channel, Comedy Central, MTV and FOX wait.
Video content available from the store is 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 require the latest version Quicktime and Quicktime 7 may not be compatible on older MacOS (only v10.3.9 and subsequent versions can support it).
Plug-ins[/title] iTunes supports visualization and device plug-ins. Visual effects plug-ins allow developers to create music-driven visual effects (iTunes includes a default visual effect, G-Force[2], licensed from SoundSpectrum). The visual effects plug-in SDK for Mac and Windows can be downloaded for free from the Apple website[3]. Device plug-ins allow support for additional music playback devices, but Apple will only license the API to bona fide OEMs that have signed a confidentiality agreement.
Podcast
iTunes version 4.9, released on June 28, 2005, added built-in Podcasting (Chinese translation: "Podcast") support. Users can subscribe to podcasts in the iTunes Music Store or by logging into the feed URL. After subscribing, the podcast will be automatically downloaded. Users can choose to update the podcast weekly, daily, hourly or manually. Apple maintains four "official" podcasts: Podfinder (Adam Curry), Street Official Real Talk (interviews with hip-hop artists), iTunes New Music Tuesday, and Apple Quarterly Earning Call. The homepage of the directory equally displays compelling podcasts from commercial radio stations and independent broadcasters. For information about Podcasting, see external links.
Video Podcast
iTunes version 6 introduced support for video podcasts, although video and RSS support already unofficially existed in version 4.9. Users can subscribe to RSS feeds via iTunes Music Store and feed URL. Video podcasts can include not only downloadable video files (MOV, MP4, M4V, MPG), but also streams and even IPTV. Downloadable files can be transferred to newer iPods, and downloadable files and streams can be played in Apple's new Front Row media center program.
Synchronize iPod with other players
Whenever an iPod is connected to it, iTunes will automatically synchronize its music and video library (the OS X version of iTunes can synchronize several Different digital audio players[4]; the Windows version of iTunes only supports iPod[5]). New tracks and playlists are automatically copied to the iPod, and tracks deleted from the computer music library will also be deleted from the iPod. The ratings of the track in the iPod will be fed back to the iTunes music library, and the audiobook will remember the last played position.
Auto-sync can be turned off to allow manual copying of individual tracks or complete playlists; however, iTunes can only copy music to iPod but not vice versa, which inspired third-party software to support Music is copied from iPod. Through some software, this work can also be done on the Unix command line.
When the iPod connected to the computer does not have enough remaining space to synchronize the music library in iTunes, a playlist with the same name as the connected iPod will be created. This playlist can be changed by the user to fill the available space.
History
iTunes evolved from SoundJam MP, a popular commercial MP3 software released by Macintosh software company Casady & Greene. Apple bought the rights to SoundJam MP and hired the three programmers who created SoundJam. The first release of iTunes was very similar to SoundJam MP, adding CD burning capabilities and a better user interface. Apple has added many important features to subsequent versions of iTunes.
Apple Computer has also developed trademarked iTunes software that runs on mobile phones such as the Motorola ROKR, Motorola RAZR and Motorola SLVR. Official download address:/itunes/overview/