Re: Data storage on CD-Audio -- bad news.

From: Marko Mäkelä (
Date: 1999-10-25 15:33:54

On Mon, 25 Oct 1999, Martijn van Buul wrote:

> Well, I haven't found time to complete my interface last weekend, but I think
> that the whole idea is still possible. Maybe not at 4 kb/s, but most
> definately at 2.2 kb/s

Yes, using e.g. Manchester coding (22050 Hz signal with phase modulation):

0 1 1 1 0      _- corresponds to 0, -_ to 1

There's also another coding from which the clock can be extracted easily,
but I don't remember how the scheme exactly was.  Neither scheme has more
than 1 "no change" in a row, and your (ncc)* (n=no change, c=change) test
pattern did survive the CD player, didn't it?

BTW, does your CD player have distortion features, such as bass boosting?
Did you try how it mangles the signal further?  And did you try the
headphone connector with different volume settings?


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