BPM Counter for Live Input channels

If you have no other source providing beats (like another deck running a digital track), you can always tap (and frequently re-tap) the master clock. This will also affect the timing of beat-aligned Traktor FX. You may want to map the master tap function to a button on your keyboard or MIDI capable controller. It's a workaround but better than nothing. Alternatively you can run a short loop of silent track with a fixed median BPM and run it as the MASTER deck, providing the clock with a tempo you can control by (software)-fader that is hopefully assigned to one of your midi hardware faders or fine +/- controls for keyboard keys. If sou activate the deck's metronome you can hear the clicking sound of the silent deck on your headphones via cue monitor to compare the deck beat with the sound coming from your turntables and adjust the deck tempo until it sits just right. With pitch bend available, you are all set. All this would work best with a complete MIDI deck or an all-in-one piece.

This may sound like a lot of work, but it's done quickly and long before you even start your set.

Does it calculate BPM of the audio source automatically?

This is really cool. I don't have turntables, but i imagine any other audio source routed through Traktor will also register. :)