Klarinet Archive - Posting 000377.txt from 2002/09

From: "Mark Charette" <charette@-----.org>
Subj: RE: [kl] MP3 - WAV - CD
Date: Thu, 19 Sep 2002 22:03:42 -0400

Not quite. WAV is 16 bits of digital bits at (normally) 44.1
Kbs/sec/channel. It's processed via a DAC (digital-to-analog converter) to
get the sound back into an analog form. That gives 22.05 Khz analog/channel
at near 98 db S/N ratio.

CD format is very, very similar - the track formats are different, but the
raw bits are just about the same. There's some extra guard tracks that are
read to help guide a laser along (things that you don't have to worry about
on a WAV file on a hard drive) along with land/pit variance (jitter, the
bug-eyed monster of CD-R recordings. The CD-R can work fine for data and be
unacceptable for sound playback).

You description of MP3 is close - there's a lot of adaptive encoding going
on that supposedly throws out frequencies that wouldn't be discernable.
With the new encoders it's quite impressive. With the older encoders it was
pretty dismal.

-----Original Message-----
From: schiffer@-----.edu
[mailto:schiffer@-----.edu]On Behalf Of Jeremy A Schiffer
Subject: RE: [kl] MP3 - WAV - CD

As I understand it:

A WAV file is exactly that: the sin wave of the sound vibrations being
recorded.

CD audio format is the inverse: 1/sin.

MP3 files are compressed versions of the WAV file. Certain frequencies are
removed, based on a sophisticated algorithm; the amount of frequencies
varying by the compression amount (when you encode MP3 files, you choose
how much compression you want). A higher compression rate will yield a
lower quality file because more frequencies are missing.

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