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aac

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Dictionary

AAC

(Advanced Audio Coding) An audio compression technology that is part of the MPEG-2 and MPEG-4 standards. AAC, especially MPEG-4 AAC, provides greater compression and better sound quality than...

Dictionary

Definition: AAC

(Advanced Audio Coding) An audio compression technology that is part of the MPEG-2 and MPEG-4 standards. AAC, especially MPEG-4 AAC, provides greater compression and better sound quality than MP3, which also came out of the MPEG standard.

Popularized by the iPod
AAC is the default format for Apple's iPod. It was chosen because it improved sound quality and also supported copy protection, which was administered through Apple's iTunes software. AAC song files purchased from the iTunes online store were sold with copy protection, but Apple dropped it in 2009 (see FairPlay). With iTunes, users may also choose to rip their CDs to AAC instead of MP3.

Profiles
AAC is available in profiles, which determine how the algorithms work to encode the audio data. Main offers the highest quality. Low Complexity (LC) is lower quality, but uses less CPU processing. Scalable Sampling Rate (SSR) is a variation of LC. Long Term Prediction was added in MPEG-4 to improve the Main profile. See aacPlus, Apple Lossless, MP3 and iPod. Following are the file extensions used for AAC:

  AAC File
  Extension   Type of AAC File
     MP4   Standard MPEG-4 video & audio
     M4A   Unprotected AAC
     M4A   Apple Lossless
     M4P   Protected AAC
     M4B   Protected AAC audiobook





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Additional Results

  • DRM licensing group plan to plug analog hole

    The AACS Licensing Authority seems to think that you don't have enough DRM in your living room and seeks to eliminate analog decoders by 2014.

    Blog posts | June 12, 2009 12:46pm PDT

  • Is imeem Mobile better than Pandora or Last.fm on the iPhone?

    One of the most popular types of applications on the iPhone is the streaming audio player. Pandora has been at the top of the App Store before and looks to be the one to beat. The service I use...

    Blog posts | May 14, 2009 12:04am PDT

  • How to convert AAC to MP3 the easy way

    Using screen shots and text, this step-by-step tutorial will show you how to convert your AAC files to MP3s without spending your valuable time filling in ID3 tag info.

  • How to Convert AAC to MP3 for free

    Using screen shots and text, this step-by-step tutorial will show you how to convert your AAC files to MP3s without spending a cent.

  • New AACS Processing Key released

    The cat and mouse game between the hackers and the AACS Licensing Authority continues as the latest MKB v3 Processing Key is released onto the web.

  • Latest AACS Processing Key released

    The cat and mouse game between the hackers and the AACS Licensing Authority continues as the latest MKB v3 Processing Key is released onto the web.

    Blog posts | May 31, 2007 4:20am PDT

  • Fragile DRM and AACS

    As has been reported elsewhere on the web, the updated AACS DRM protection system (which includes revocation for previously compromised keys) has already been broken even before HD titles (HD-DVD...

    Blog posts | May 17, 2007 10:05am PDT

  • AACS broken - before it's patched!

    AACS, the copy-protection scheme used on HD DVD discs has been broken again. But what's different this time is that it's been broken six days before the new, updated version is released.

    Blog posts | May 17, 2007 8:47am PDT

  • A Digg riot and AACS

    AACS, the DRM technology used to protect HD-DVD and Blu-Ray discs (though Blu-Ray has additional schemes it can use), has been broken for awhile, at least since February 13th when this Wired blog...

    Blog posts | May 2, 2007 9:05am PDT

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