Apple Audio Mastering Tools (Apple推出的AAC轉檔保真軟體)
http://images.apple.com/itunes/maste...go20120217.png
http://www.apple.com/itunes/mastered-for-itunes/
除了iTunes本身已經推出 Masters for iTunes 系列的音樂，利用高保真的技術重新轉檔過的AAC (iTunes Plus format)
http://www.apple.com/itunes/inside-i...for iTunes.jpg
本身Apple也開放此轉檔技術軟體的下載 Apple Audio Mastering Tools
可以親自體驗由WAV或是AIFF轉檔到AAC (iTunes Plus format)，是否有差異，還能做比較喔!
快來嘗試看看吧!
Mastering Tools
To hear how music will sound after it’s encoded to make important creative choices during the mastering process, download these tools. The Mastered for iTunes droplet is a simple, standalone drag-and-drop tool that automates the creation of iTunes Plus format masters, allowing for a preview of songs using the same world-class technology used to encode the entire catalog for the iTunes Library.
Apple Audio Mastering Tools Read Me
This installer installs the following tools that you can use to properly master compressed audio files:
Master for iTunes Droplet, AURoundTripAAC, and afclip. The following summaries include more
information about each of these audio mastering tools and where they will be installed.
Master for iTunes Droplet
This droplet automates the creation of iTunes Plus format masters.
The droplet is installed in: /Applications/Utilities
AURoundTripAAC
This Audio Unit allows you to compare audio encoded using iTunes Plus AAC against a source audio file.
It also includes clip and peak detection, as well as a simple listening test environment. It can be used in
any Audio Unit host application, such as Logic or AU Lab.
The Audio Unit is installed in: /Library/Audio/Plug-Ins/Components
afclip
You can use the command-line tool afclip to check any file for clipping. This tool works by examining an
audio file and identifying areas where clipping has occurred. For more information about this tool, run
afclip -h from the command line.
This tool is installed in: /usr/local/bin
注意事項*
AAC是advanced audio coding : 有損失壓縮
ALAC是Apple lossless audio coding ：無損失壓縮
兩者常見的副檔名都可以為m4a，不要搞混囉!
Masters for iTunes 是用iTunes Plus格式，這也是AAC，256Kbps，VBR（variable bit rate）
目的在於用高保真的有損壓縮方式，創造出小容量卻不會犧牲太多音質的格式。
