Funkin/source/VisShit.hx

package;

import dsp.FFT;
import flixel.math.FlxMath;
import flixel.system.FlxSound;
import lime.utils.Int16Array;

using Lambda;

class VisShit
{
	public var snd:FlxSound;
	public var setBuffer:Bool = false;
	public var audioData:Int16Array;
	public var sampleRate:Int = 44100; // default, ez?
	public var numSamples:Int = 0;

	public function new(snd:FlxSound)
	{
		this.snd = snd;
	}

	public function funnyFFT(samples:Array<Float>, ?skipped:Int = 1):Array<Array<Float>>
	{
		// nab multiple samples at once in while / for loops?

		var fs:Float = 44100 / skipped; // sample rate shit?

		final fftN = 1024;
		final halfN = Std.int(fftN / 2);
		final overlap = 0.5;
		final hop = Std.int(fftN * (1 - overlap));

		// window function to compensate for overlapping
		final a0 = 0.5; // => Hann(ing) window
		final window = (n:Int) -> a0 - (1 - a0) * Math.cos(2 * Math.PI * n / fftN);

		// NOTE TO SELF FOR WHEN I WAKE UP

		// helpers, note that spectrum indexes suppose non-negative frequencies
		final binSize = fs / fftN;
		final indexToFreq = function(k:Int)
		{
			var powShit:Float = FlxMath.remapToRange(k, 0, halfN, 0, 4.3); // 4.3 is almost 20khz

			return 1.0 * (Math.pow(10, powShit)); // we need the `1.0` to avoid overflows
		};

		// "melodic" band-pass filter
		final minFreq = 20.70;
		final maxFreq = 4000.01;
		final melodicBandPass = function(k:Int, s:Float)
		{
			// final freq = indexToFreq(k);
			// final filter = freq > minFreq - binSize && freq < maxFreq + binSize ? 1 : 0;
			return s;
		};

		var freqOutput:Array<Array<Float>> = [];

		var c = 0; // index where each chunk begins
		var indexOfArray:Int = 0;
		while (c < samples.length)
		{
			// take a chunk (zero-padded if needed) and apply the window
			final chunk = [
				for (n in 0...fftN)
					(c + n < samples.length ? samples[c + n] : 0.0) * window(n)
			];

			// compute positive spectrum with sampling correction and BP filter
			final freqs = FFT.rfft(chunk).map(z -> z.scale(1 / fftN).magnitude).mapi(melodicBandPass);

			freqOutput.push([]);

			// if (FlxG.keys.justPressed.M)
			// trace(FFT.rfft(chunk).map(z -> z.scale(1 / fs).magnitude));

			// find spectral peaks and their instantaneous frequencies
			for (k => s in freqs)
			{
				final time = c / fs;
				final freq = indexToFreq(k);
				final power = s * s;
				if (FlxG.keys.justPressed.I)
				{
					trace(k);

					haxe.Log.trace('${time};${freq};${power}', null);
				}
				if (freq < maxFreq)
					freqOutput[indexOfArray].push(power);
				//
			}
			// haxe.Log.trace("", null);

			indexOfArray++;
			// move to next (overlapping) chunk
			c += hop;
		}

		if (FlxG.keys.justPressed.C)
			trace(freqOutput.length);

		return freqOutput;
	}

	public function checkAndSetBuffer()
	{
		if (snd != null && snd.playing)
		{
			if (!setBuffer)
			{
				// Math.pow3
				@:privateAccess
				var buf = snd._channel.__source.buffer;

				// @:privateAccess
				audioData = cast buf.data; // jank and hacky lol! kinda busted on HTML5 also!!
				sampleRate = buf.sampleRate;

				trace('got audio buffer shit');
				trace(sampleRate);
				trace(buf.bitsPerSample);

				setBuffer = true;
				numSamples = Std.int(audioData.length / 2);
			}
		}
	}
}