timecode.txt

Traktor Scratch’s timecode vinyl and timecode CDs contain an audio signal
constructed from two sinus waves with a frequency of 2 KHz. Serato Scratch and
many other competitors have frequencies of 1khz. This signal is analogue and
can be brought into to the computer through any audio interface.  Once in the
computer, the timecode decoder extracts three different types of information
from the incoming signal:

Playback speed of the timecode vinyl or timecode CD, respectively,
Playback direction (forward, backwards) and
Current playback position on the timecode vinyl or on the timecode CD.