Re: a Dreaming Plug discovery?

[Ulrich Grepel <uli@zoodle.robin.de>]

Hi!

Andy asks:
> Another question: Since we can more or less isolate parts of
> Kate's music that exist only on left or right channels, is it not
> now also possible for someone to write a program that
> would record the Dreaming-Plug signal, then search for
> itself within the recording as a whole and cancel itself out?

First thing here: there already is (at least) one program that does
emulate the Dreaming Plug in software: Cool Edit (Windows) does the
job. That program has a myriad of features in it, and I haven't
figured out all of them, maybe there is a way to do the above,
I don't know. Let's think:

l = l' + c           r = r' + c

Dreaming-plug:

l & r -> l' & r'

or

l' + c & r' + c -> l' & r',

that is:

x+z & y+z -> x&y

Then:

l' & l
=
l'+0 & l'+c
=
0+l' & c+l' -> 0 & c

So feeding the original left signal and the Dreaming-Plug manipulated
left signal should give the center signal alone.

By the way:

If you've got a Dolby Surround receiver/amplifier/whatever, then you
should be able to get a Dreaming-Plug like effect in yet another way:
here we have more or less the following:

l & r -> l' & r' & c & back

l' and r' are more or less the result of the Dreaming Plug. c is the
center speaker and is what Andy is looking for. Back is yet another
signal we haven't discussed so far. The back signal is the stuff that
is in both, right and left, original channels, except that the phase
is shifted for 180 degrees (= one signal is inverted). If you only
connect one speaker to your surround system, you should be able to
get any desired effect here.

Bye,

Uli


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