| 1 | // js/worklets/bitcrusher.js |
| 2 | |
| 3 | class BitcrusherProcessor extends AudioWorkletProcessor { |
| 4 | constructor() { |
| 5 | super(); |
| 6 | this.phase = 0; |
| 7 | this.lastSample = [0, 0]; |
| 8 | } |
| 9 | |
| 10 | static get parameterDescriptors() { |
| 11 | return [{ |
| 12 | name: 'bitDepth', |
| 13 | defaultValue: 8, |
| 14 | minValue: 1, |
| 15 | maxValue: 16, |
| 16 | automationRate: 'k-rate' |
| 17 | }, { |
| 18 | name: 'sampleRateReduction', |
| 19 | defaultValue: 1, |
| 20 | minValue: 1, |
| 21 | maxValue: 50, |
| 22 | automationRate: 'k-rate' |
| 23 | }]; |
| 24 | } |
| 25 | |
| 26 | process(inputs, outputs, parameters) { |
| 27 | const input = inputs[0]; |
| 28 | const output = outputs[0]; |
| 29 | |
| 30 | if (!input || !input[0]) { |
| 31 | return true; |
| 32 | } |
| 33 | |
| 34 | const bitDepth = parameters.bitDepth[0] || parameters.bitDepth; |
| 35 | const sampleRateReduction = parameters.sampleRateReduction?.[0] || 1; |
| 36 | const step = 2 / Math.pow(2, bitDepth); |
| 37 | |
| 38 | for (let channel = 0; channel < input.length; channel++) { |
| 39 | const inputChannel = input[channel]; |
| 40 | const outputChannel = output[channel]; |
| 41 | |
| 42 | for (let i = 0; i < inputChannel.length; i++) { |
| 43 | // Sample rate reduction |
| 44 | this.phase++; |
| 45 | if (this.phase >= sampleRateReduction) { |
| 46 | this.phase = 0; |
| 47 | // Quantize the sample |
| 48 | const sample = inputChannel[i]; |
| 49 | this.lastSample[channel] = Math.round(sample / step) * step; |
| 50 | |
| 51 | // Add some aliasing artifacts for extra grit |
| 52 | if (bitDepth < 4) { |
| 53 | this.lastSample[channel] *= (1 + Math.random() * 0.1 - 0.05); |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | outputChannel[i] = this.lastSample[channel]; |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | return true; |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | registerProcessor('bitcrusher-processor', BitcrusherProcessor); |