FREE Tools for editing AAC and M4A files:
Audacity 1.3 beta (Support for AAC format) (Free)
Audacity 1.2 cannot import or export AC3, AMR(NB), M4A, WMA or most other proprietary file formats due to licensing and patent restrictions.
However, the Beta 1.3 version of Audacity can import or export these and many additional formats, if you install the optional FFmpeg library.
FFmpeg also allows Audacity to import audio from video files. Note that on Mac, Audacity Beta has built-in support for M4A import without installing FFmpeg, using the QuickTime components supplied by the operating system.
Audacity 1.3 beta
Plugins:
ffmpeg
FFmpeg_v0.6.2
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VLC Player-VideoLAN Client (Free)
With the VLC player, you can enjoy your AAC audio files quickly. The player directly supports AAC decoding without the need for DirectShow filters or special codecs to be installed. If you are looking for a quick solution then this is certainly it, but if you want to look at other examples of these players or learn to play with Windows Media Player and store it in your Media Library.
VLC
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Foobar 2000 (Free)
Another Player with Direct Support for FLAC
One of the most excellent audio players and converters available is Foobar 2000. It is available as a free download from AfterDawn and it natively supports the Advanced Audio Coding (AAC) format. It also will allow you to easily convert it to another format or edit the tag information.
Foobar
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Features of AAC format:
AAC was promoted as the successor to MP3 for audio coding at medium to high bitrates. When compared side-by-side, AAC proves itself worthy of replacing MP3 as the new Internet audio standard the advantages over MP3 are:
* Improved compression provides higher-quality results with smaller file sizes.
* Support for multichannel audio, providing up to 48 full frequency channels.
* Higher resolution audio, yielding sampling rates up to 96 kHz.
* Improved decoding efficiency, requiring less processing power for decode.
A file with the AAC file extension is an MPEG-2 Advanced Audio Coding file.
Other types of files may also use the AAC file extension. If you know of any additional file formats that use the AAC extension, please let me know so I can update this information.
AAC, or Advanced Audio Coding, is often considered to be the successor of the MP3 format. This may be true in the market for legal downloads, but not really for music file sharing. However, the AAC format is also used with video (used with MP4 & 3GP container) and it does provide better audio quality than MP3, keeping the bitrate lower. This makes AAC a suitable audio format for portable players like iPods.