BlitzMax-FFT-Class V0.99

This class contains various functions of Fast Fourier Transformation in the language Basic (BitzMax)

At Syntaxbomb ou will find a tutorial with Discussion and additional informations: https://www.syntaxbomb.com/tutorials/fft-fast-fourier-transformation-in-blitzmax-ng/

Reference:

FFT.AnalyseTAudioSample()

Function AnalyseTAudioSample(Audio:TAudioSample, Start:Int, Length:Int, CallBackName: Byte Ptr)

This is the universal MAIN function when you have a trad. TAudioSample in SF_MONO16LE. It expects a TAudioSample and the desired window size. At the end the function reports "ready" to a callback function. Example:

Audio:TAudioSample = LoadAudioSample("...."
FFT.AnalyseTAudioSample Audio, 0, 2048 , MyDoneFunction
....
Function MyDoneFunction()
   local Out:Double[] = FFT.GetResultArray()
   ' do whatever you want to do
End Function

FFT.MainFrequency()

Function MainFrequency:Int()

returns the loudest frequency found in audio Example:

...
local Loudest:Int = FFT.MainFrequency()

FFT.GetListOfFrequencies()

Function GetListOfFrequencies:TList( sorted:Int=1, NewSampleRate:Int=0)

returns a list of peak frequencies found by FFT Example:

FFT.GetListOfTones()

GetListOfTones:TList(sorted:Int=1, NewSampleRate:Int=0)

Returns a list of Tones (as MIDI NOTE NUMBERS) found by FFT

Example:

FFT.MidiFrom()

Function MidiFrom:Int(Frequency:Double)

Calculates the MIDI number related to a frequency

Example:

FFT.GetResultArray()

Function GetResultArray:Double[](mode:Int=1)

returns the raw result array of the FFT Example:

FFT.Analyse()

Function AnalyseTAudioSample(Audio:TAudioSample, Start:Int, Length:Int, CallBackName: Byte Ptr)

This is a deeper MAIN function for valid Audio in a 64bit-"Double" array give FFT a audio adress and a window size at the end the function reports "ready" with a callback function.

Example:

FFT.Analyse Audio, 2048 , MyDoneFunction
....
Function MyDoneFunction()
   local Out:Double[] = FFT.GetResultArray()
   ' do whatever you want to do
End Function

FFT.Resolution()

Function Resolution:Int()

Returns the width of one band of the analysis in Hz

Example:

FFT.WindowTime()

Function WindowTime:Int()

Returns the length of the examined audio in msec

Example:

FFT.RemoveBand()

Function RemoveBand(FromHz:Int, ToHz: Int) You can manipulate the result of the FFT. Afterward you can recreate the audio from this. Here: removed frequencies in an audio material (still in development).

Example:

...
FFT.Remove(2000,3000)
NewAudio:Double=FFT.InverseFFT()

FFT.InverseFFT()

Function InverseFFT:Double[]() You can manipulate the result of the FFT. Afterward you can recreate the audio from this. Here: Calculates back the audio signal from a given frequencies array (still in development).

Example:

...
FFT.Remove(2000,3000)
NewAudio:Double=FFT.InverseFFT()