CDs and Sound Quality

A place to discuss the science of computers and programs, from algorithms to computability.

Formal proofs preferred.

Moderators: phlip, Moderators General, Prelates

Posts: 112
Joined: Sun Mar 18, 2007 10:30 pm UTC
Location: Chicago

CDs and Sound Quality

Postby imMAW » Sun Aug 10, 2008 1:18 am UTC

I'm not really sure if this belongs in computer science or elsewhere, so feel free to move it if you want.

CD's have about 700 megabytes and can store 80 minutes of audio, according to wikipedia.
So that means the music is at 700*1000 / 80*60 kbps, or about 146 kbps. Yet the quality of CD music is much better than mp3 or other music at around 146 kbps, right?
Why is this?

User avatar
Posts: 3072
Joined: Mon Oct 22, 2007 5:28 pm UTC
Location: Beaming you up

Re: CDs and Sound Quality

Postby headprogrammingczar » Sun Aug 10, 2008 2:23 am UTC

It has to do with how it is encoded before being burned. I just tried to explain it without using super-big-ulous words, so someone else can give you that.

Your 'microphone' in your ears is not perfect. It is puny and way the way in there. It does not pick up all frequencies with equal preference. After some big math, people figured out that there is a big difference between frequency and wavelength when it comes to acoustics. If you lose precision where the ear won't care, you can do something awesome, like double the dynamic range or something.

This is just me making an educated guess though. I could not find specifications for different audio formats.
<quintopia> You're not crazy. you're the goddamn headprogrammingspock!
<Weeks> You're the goddamn headprogrammingspock!
<Cheese> I love you

User avatar
Posts: 887
Joined: Fri Apr 20, 2007 11:45 pm UTC
Location: Durham, England

Re: CDs and Sound Quality

Postby crazyjimbo » Sun Aug 10, 2008 3:03 am UTC

kbps is kilobits not bytes, so you need to multiply your figure by 8.

User avatar
Posts: 405
Joined: Sun Dec 30, 2007 10:12 pm UTC
Location: North Lincs., UK

Re: CDs and Sound Quality

Postby Dropzone » Sun Aug 10, 2008 1:47 pm UTC

crazyjimbo is right; the actual bitrate is around 1400 kbps (see the Wikipedia article).

Return to “Computer Science”

Who is online

Users browsing this forum: No registered users and 6 guests