itunes Mp3 and AAC format

用itunes 係 mp3 format 最好的

MP3 - The most common kind of digital music file. MP3s usually have no usage restrictions and can be used on as many computers or iPods as you want. Short for MPEG Layer-3, a digital media standard developed by the Motion Picture Experts Group (MPEG).

AAC - Stands for Advanced Audio Coding. It is a newer kind of audio file that has been promoted as a successor to the MP3. It offers higher-quality sound than an MP3, but takes up about the same amount of space. It is a standard that was developed by a group of companies.

you can choose what file format you want the songs to be saved in. Different file formats have different strengths and weaknesses – generally trading the size of the resulting file for the sound quality of the music.

The two most common file types in iTunes are MP3 and AAC, though iTunes also offers Apple Lossless Encoding, AIFF, and WAV (these last two are high-quality, uncompressed file types used for CD burning. Avoid using these in iTunes unless you really know what you're doing and have a good reason).

AAC files are generally higher quality and slightly smaller than MP3 files of the same song.

personally, the difference between MP3 and AAC can not be easily heard by most computers and iPod. But i use AAC for it has a smaller file size

2008-03-26 01:09:29 補充：
iTunes 初出時係冇AAC 嘅，後來係iTunes 4加入AAC時 Steve Jobbs 係 2003 年Keynote (蘋果的發佈會)中提過AAC無論 file size 同 音質都比MP3優勝。