Getting full audio frequency spectrum with Tobybears VST Template?

Question

I'm trying to make a simple frequency analyzer VST plugin using Tobybears VST Template for Delphi.

The problem I'm having is that I cant seem to find any documentation or information about how to get something like an array of values that represent the different frequencies from a chunk of audio data that is recieved from the host.

Does anybody have a clue on how to do this?

Also, my VST host keeps crashing whenever I try to use the DelphiASIOVst library, which is another library for making custom VSTs.

Thanks!

Answer 1

The Tobybears VST Template is obsolate(vst 2.3). Rather use the DAV project on sourceforge, as sugested by Shannon.(which make some vst 2.4)

About the analysis, it's quite easy, you basically have to make some FFT on the signal (you buffer the input and when 2^n data have been accumulated you make a FFT), and then you compute the hypothenus of each imaginary,real pair to get the aproximative amplitude of a band...then you plot on a graph...In combination with a envelope follower and some GUI programming skills you'll get someting like the Voxengo Span...

Answer 2

VST plugins receive audio signals as time domain signals. The audio signal data doesn't contain frequency information (which is why you can't find any documentation).

To implement a frequency analyzer you'll need to transform the received time domain signal into a frequency domain signal. Performing a Fast Fourier Transformation (FFT) is the standard way to transform time domain signals into frequency domain signals.