Audio Filters

Hold & drag to sweep a low-pass filter over the music in real time, DJ style: left/right controls the cutoffFrequency, up/down the resonance. Release to remove the filter.

Audio filters are attached to a bus: here the music plays on bus 1 and the filter is added to that same bus, so pressing B plays a blip on the default bus 0 that never gets filtered.

// Play the music on bus 1
// play(position, loop, volume, pan, pitch, bus)
musicPlayer = musicSound.play(0, true, 0.5, null, null, 1);

// A low-pass filter processing bus 1: only the music gets filtered
var lowPass = new LowPassFilter();
audio.addFilter(lowPass, 1);

// Filter params can be changed live, while the filter is running:
// this is what the pointer sweeps in this example
lowPass.cutoffFrequency = 800;
lowPass.resonance = 2.5;

// When released, the filter is not removed: its params are just reset
// to neutral values that let the sound through unchanged
lowPass.cutoffFrequency = 20000; // well above the audible range
lowPass.resonance = 0.707;       // no resonance

The logo pulses on the music beat. Instead of a separate timer that would drift away from the audio, the current beat is derived from the actual playback position of the music player, so the pulse stays in sync with what you hear:

// In update(): the synth music is 120 BPM, one beat every 0.5 second
var beat = Std.int(musicPlayer.position / 0.5);
if (beat != lastBeat) {
    lastBeat = beat;
    // ... pulse! ...
}

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