[G4] AIFF, MP3, Quality Issue

[Alex]

On May 14, 2005, at 19:57, Anne Keller-Smith wrote:

> Originally I converted my AIFFs to MP3 before burning to CD, as I 
> thought CD players played MP3s.

CD players play audio CDs. Audio data on an audio CD is stored neither 
as AIFF nor as MP3, and it's not even organized in discrete files as 
you are accustomed to see on computers. Some CD players and many, if 
not most, DVD players can also play MP3 CDs. The latter are actually 
ISO9660 data CDs, which contain MP3 files.

>  Then I discovered iTunes was reconverting the MP3s back to AIFFs 
> before burning the CD.

No. MP3 is a format which allows for the lossy compression of sound, 
i.e., sound is compressed, and some of the audio data is thrown away, 
to reduce file size. The price is reduction in quality. An MP3-encoded 
file never sounds as good as the original, but for many users it 
doesn't matter, because they can't tell the difference. When an 
application, such as iTunes, creates an audio CD from MP3 files, it 
decompress the MP3 on-the-fly and writes audio data to disc. The data 
thrown away cannot be re-created, so an audio CD created from MP3 does 
not sound any better than the original MP3. Hence, the only reason to 
write an audio CD from MP3 files is to listen to them on a player which 
does not support the MP3 format. Otherwise, it's best to write MP3 CDs, 
not audio CDs, when your source is MP3.

When you insert an audio CD in your Mac, Finder shows it as having AIFF 
files. That's an illusion, a convenience for the user (on a PC, they 
would show up as WAVE files); in reality, there are no files on the 
disc.

<0x0192>