class OwrxAudioProcessor extends AudioWorkletProcessor { constructor(options){ super(options); // initialize ringbuffer, make sure it aligns with the expected buffer size of 128 this.bufferSize = Math.round(options.processorOptions.maxBufferSize / 128) * 128; this.audioBuffer = new Float32Array(this.bufferSize); this.inPos = 0; this.outPos = 0; this.port.addEventListener('message', (m) => { if (typeof(m.data) === 'string') { const json = JSON.parse(m.data); if (json.cmd && json.cmd === 'getBuffers') { this.reportBuffers(); } } else { // the ringbuffer size is aligned to the output buffer size, which means that the input buffers might // need to wrap around the end of the ringbuffer, back to the start. // it is better to have this processing here instead of in the time-critical process function. if (this.inPos + m.data.length <= this.bufferSize) { // we have enough space, so just copy data over. this.audioBuffer.set(m.data, this.inPos); } else { // we don't have enough space, so we need to split the data. const remaining = this.bufferSize - this.inPos; this.audioBuffer.set(m.data.subarray(0, remaining), this.inPos); this.audioBuffer.set(m.data.subarray(remaining)); } this.inPos = (this.inPos + m.data.length) % this.bufferSize; } }); this.port.addEventListener('messageerror', console.error); this.port.start(); } process(inputs, outputs) { if (this.remaining() < 128) return true; outputs[0].forEach((output) => { output.set(this.audioBuffer.subarray(this.outPos, this.outPos + 128)); }); this.outPos = (this.outPos + 128) % this.bufferSize; return true; } remaining() { const mod = (this.inPos - this.outPos) % this.bufferSize; if (mod >= 0) return mod; return mod + this.bufferSize; } reportBuffers() { this.port.postMessage(JSON.stringify({buffersize: this.remaining()})); } } registerProcessor('openwebrx-audio-processor', OwrxAudioProcessor);