Date: Fri May 10 19:46:56 2002
From: flaps
Newsgroups: alt.folklore.urban
Subject: Re: Green marker on CD (Was: [NEW FAQ])
References: <aapoh3$t33$1@flood.xnet.com> <YmFydGljdXM=.42dde14bd256b069de0dea05ff7f1f3a@1020362842.cotse.net> <MPG.173c9126c5264ae698994f@news.supernews.com> <ain5dug94q0l159rltbdfsb05csnfu5fc1@enews.newsguy.com> <8OCl0SC1w-B@khms.westfalen.de> <ab2dbf$jp2$1@reader1.panix.com> <B8FCCA919668EC169@0.0.0.0> <B8FE19C996681A5E62@10.0.1.3> <c1b18814.0205081011.4aad6b1@posting.google.com> <B900B7069668E5933@10.0.1.2>
X-No-Ahbou: yes

slavins@localhost (Simon Slavin) writes:
>Prove that what you heard was
>
>a) the result of the dropping of CD data
>b) the result of the dropping of just one sample of CD data

Here you are.

In the directory
http://www.dgp.toronto.edu/~flaps/clicky/
, the discerning AFU reader will find some sound files.  I don't know what
sound file format is de rigeur on the web these days, but I think that
everyone can play "wave" (".wav") files.  Maybe.

The file "good.wav" contains a three-second pure tone sampled at 44100 Hz,
which is the audio CD sampling rate.  The file "click.wav" differs from this
file in a single sample, at time 1 second.  The click is very easily audible.

Your computer might not be able to play 44100 Hz sound files very well
if it is not moderately new (they sounded terrible on the computer I'm
sitting at at the moment and I had to go upstairs to play them on our
shiny new computer to check them).  It's quite a lot of data for a feeble
computer to pump out.  So I've also generated a pair of files at half the
sample rate.  These are called "smallgood.wav" and "smallclick.wav", in the
same directory.  I think that any ol' computer can play these acceptably.
If you have software which interprets the "wave" file format, that is.

That is, the smaller files do perform identically, but without the larger
ones, there could be an AFUian arguing that the click would disappear at the
CD sampling rate.  Hence I present both the smaller and the bigger files.

The program I just threw together to generate this data is also in that
directory, called clickysine.c.  It is short, and simple if you know how to
work with sine waves for audio purposes.  It can output the samples either
in binary or text.  Many sound editing programs can read one or the other
of these formats, if not wave format.  I generated the wave files from the
binary sound data using the irix "sfconvert" command.