Can I retrieve the frequency of the mp3 file being played on the software without using a microphone?
I was wondering if there was any way that the frequency being displayed can come straight from the mp3 file through MIDI.
Traktor doesn't do that as far as I'm aware (I've been using Traktor for quite a few years now).
You might be able to find a VST/AU plugin that will give you an on-screen analyser, so it's not inconceivable that you'll find one that will let you pipe the data out somewhere else. Traktor doesn't natively host plugins but there are workarounds for that.
I'm not aware of a standardised way to send spectrum analyser data over MIDI, but I don't suppose it would be too hard to encode it e.g. using a CC# per channel.
So yeah, there's no easy way but you might be able to hack something together. Not sure it'd do much for Traktor's stability so I don't know if this is a wise way to proceed.
It might be easier to get a couple of MSGEQ7 chips and analyse the analogue signal on the way out to the amplifier.