Ok, I know others have already answered this, but I spent a good 20 minutes working on it earlier, and I'm gonna send it anyway... so there! :-p
The AIFF (Audio Interchange File Format) is the default format Apple uses to read audio files from regular music CDs, i.e., the kind you would play in your stereo. These files typically run about 10-12MB per minute of audio. So a typical 3.5 minute song would be about 35-40MB. MP3 (Mpeg Layer 3) is the most common form of audio file on the internet. The MP3 compression algorithm allows the 35-40MB AIFF (or WAV for Windows) file to be compressed to about 1/10th its original size (allowing for standard settings of 44.1Khz/128Kbps). Apple's current standard is AAC (Advanced Audio Codec). This is the format that is sold via the iTunes Music Store. It provides higher quality audio than MP3 at approximately the same size. In addition, Apple is able to embed its DRM, or Digital Rights Management, key into each audio track, to prevent unauthorized copying of purchased music. AAC currently will only play on iPods and iTunes. One thing to keep in mind is that both MP3 and AAC are considered lossy formats, meaning data is lost in translation. It's not likely you will hear the difference unless you have a very well trained ear, but it's good to keep in mind. Let's say you have a song on a music CD you want to add to your iTunes library. You import the song as an AAC file. You probably would have a hard time telling which is the original CD and which is AAC, even if you played them both side by side. But if you were to burn the AAC back to an audio CD, the data that was originally lost in translation to AAC is still gone. It's not going to miraculously reappear just because you're converting it back to its original format. Then if you play the two CDs side by side, you might be more likely to hear the difference, even though the difference would be very small. Data loss can be reduced by using a higher bitrate (128Kbps is standard) and a higher frequency (44.1Khz is standard). By default, when I import a CD, I use the AAC codec, since I only use iTunes and my iPod, and I use a bitrate of 160Kbps with a frequency of 48Khz. This increases the size of the files by maybe 33%, but they sound much better than using the standard settings. So instead of a file being 3.5MB, it might be 5MB. Not a huge difference with today's hard drives. If I used a 3rd party MP3 player, I would probably use MP3 at 192Kbps and 48Khz. Again, files would be about 50% larger than if I had used the default settings. Hope this helps! Bryan C. Forrest Macintosh Specialist LifeNet http://www.lifenet.org -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: text/enriched Size: 2720 bytes Desc: not available Url : http://www.math.louisville.edu/pipermail/macgroup/attachments/20050124/1d3c3aea/attachment.bin
