On Mon, Oct 07, 2002 at 09:18:38PM +0200, CK wrote: > > you could just count the zero crossings per second and take the ratio > > compared to the expected 440 Hz.
But DJ techniques include manipulating the speed of the record - faster or slower. So if all you do is measure frequency, you won't know whether you've increased the position or the speed. So I think something like the suggestion of stereo-encoding two signals is necessary. That way the speed and direction can always be determinied by looking at the sawtooth wave, e.g. on the left channel, as suggested previously; and the *position* can be determined by comparing the ratio of the sawtooth wave to a time-varying signal on the right channel. Encoding stereo to an LP is no problem - the needle vibrates along two axes. There's a limit to how much stereo separation you can get (I forget, it might be like 40-45 dB) but that shouldn't be too hard to account for. --PW -- Paul Winkler "Welcome to Muppet Labs, where the future is made - today!"
