path: root/static/mic-worklet.js

// Microphone capture worklet: resamples the context rate to 48 kHz mono,
// optionally runs RNNoise (WASM) on 10 ms (480-sample) sub-frames, and
// posts 20 ms frames (960 Float32 samples) together with their RMS level.
const OUT_RATE = 48000;
const FRAME_SAMPLES = 960;
const RNNOISE_FRAME_SAMPLES = 480;
const PCM16_SCALE = 32768;

function instantiateRnnoise(wasmBinary) {
  let memory = null;
  const resizeHeap = (requestedSize) => {
    if (!memory) return 0;
    const pages = ((requestedSize >>> 0) - memory.buffer.byteLength + 65535) >>> 16;
    try {
      memory.grow(pages);
      return 1;
    } catch {
      return 0;
    }
  };
  const memcpyBig = (dest, src, num) => {
    if (!memory) return;
    new Uint8Array(memory.buffer).copyWithin(dest >>> 0, src >>> 0, (src + num) >>> 0);
  };
  const imports = {
    a: { a: resizeHeap, b: memcpyBig },
    env: {
      emscripten_resize_heap: resizeHeap,
      emscripten_memcpy_big: memcpyBig,
      __assert_fail: () => {
        throw new Error("RNNoise WASM assertion failed");
      },
    },
  };

  const buildDenoiser = (instance) => {
    const exp = instance.exports;
    memory = exp.memory || exp.c;
    if (typeof exp.emscripten_stack_init === "function") exp.emscripten_stack_init();
    const initRuntime = exp.__wasm_call_ctors || exp.d;
    if (typeof initRuntime === "function") initRuntime();

    const rnnoiseInit = exp.rnnoise_init || exp._rnnoise_init || exp.e;
    const rnnoiseCreate = exp.rnnoise_create || exp._rnnoise_create || exp.f;
    const malloc = exp.malloc || exp._malloc || exp.g;
    const rnnoiseDestroy = exp.rnnoise_destroy || exp._rnnoise_destroy || exp.h;
    const free = exp.free || exp._free || exp.i;
    const rnnoiseProcessFrame = exp.rnnoise_process_frame || exp._rnnoise_process_frame || exp.j;

    const state = rnnoiseCreate(0);
    const ptrIn = malloc(RNNOISE_FRAME_SAMPLES * 4);
    const ptrOut = malloc(RNNOISE_FRAME_SAMPLES * 4);
    if (!state || !ptrIn || !ptrOut) {
      if (state) rnnoiseDestroy(state);
      if (ptrIn) free(ptrIn);
      if (ptrOut) free(ptrOut);
      throw new Error("Failed to allocate RNNoise WASM state");
    }

    let heapF32 = new Float32Array(memory.buffer);
    let destroyed = false;

    return {
      processFrame480(frame, offset) {
        if (destroyed) return 0;
        if (heapF32.buffer !== memory.buffer) {
          heapF32 = new Float32Array(memory.buffer);
        }
        const inBase = ptrIn >> 2;
        const outBase = ptrOut >> 2;
        for (let i = 0; i < RNNOISE_FRAME_SAMPLES; i++) {
          heapF32[inBase + i] = frame[offset + i] * PCM16_SCALE;
        }
        const vad = rnnoiseProcessFrame(state, ptrOut, ptrIn);
        if (heapF32.buffer !== memory.buffer) {
          heapF32 = new Float32Array(memory.buffer);
        }
        for (let i = 0; i < RNNOISE_FRAME_SAMPLES; i++) {
          const s = heapF32[outBase + i] / PCM16_SCALE;
          frame[offset + i] = s < -1 ? -1 : s > 1 ? 1 : s;
        }
        return vad;
      },
      reset() {
        if (destroyed) return;
        if (typeof rnnoiseInit === "function") {
          rnnoiseInit(state, 0);
        }
      },
      destroy() {
        if (destroyed) return;
        destroyed = true;
        try { rnnoiseDestroy(state); } catch { /* ignore */ }
        try { free(ptrIn); } catch { /* ignore */ }
        try { free(ptrOut); } catch { /* ignore */ }
      },
    };
  };

  return WebAssembly.instantiate(wasmBinary, imports).then((res) => buildDenoiser(res.instance || res));
}

class Ts6MicCapture extends AudioWorkletProcessor {
  constructor(options) {
    super();
    this.ratio = sampleRate / OUT_RATE; // input samples per output sample
    this.t = 0;      // fractional read position; -1 refers to `last`
    this.last = 0;
    this.frame = new Float32Array(FRAME_SAMPLES);
    this.offset = 0;

    const opts = (options && options.processorOptions) || {};
    this.rnnoiseEnabled = Boolean(opts.rnnoiseEnabled);
    this.rnnoise = null;
    this.disposed = false;

    this.port.onmessage = (e) => this.onMessage(e.data);
    if (opts.wasmBinary) {
      this.initRnnoise(opts.wasmBinary);
    }
  }

  onMessage(msg) {
    if (!msg || typeof msg !== "object") return;
    if (msg.type === "rnnoise-init" && msg.wasmBinary) {
      if (typeof msg.enabled === "boolean") this.rnnoiseEnabled = msg.enabled;
      this.initRnnoise(msg.wasmBinary);
    } else if (msg.type === "rnnoise-enable") {
      const next = Boolean(msg.enabled);
      if (next && !this.rnnoiseEnabled && this.rnnoise) {
        this.rnnoise.reset();
      }
      this.rnnoiseEnabled = next;
    } else if (msg.type === "rnnoise-clear") {
      this.rnnoiseEnabled = false;
      if (this.rnnoise) {
        this.rnnoise.destroy();
        this.rnnoise = null;
      }
      this.port.postMessage({ type: "rnnoise-status", ready: false });
    } else if (msg.type === "dispose") {
      this.disposed = true;
      if (this.rnnoise) {
        this.rnnoise.destroy();
        this.rnnoise = null;
      }
    }
  }

  initRnnoise(wasmBinary) {
    instantiateRnnoise(wasmBinary)
      .then((denoiser) => {
        if (this.disposed) {
          denoiser.destroy();
          return;
        }
        if (this.rnnoise) this.rnnoise.destroy();
        this.rnnoise = denoiser;
        this.port.postMessage({ type: "rnnoise-status", ready: true });
      })
      .catch((err) => {
        this.port.postMessage({
          type: "rnnoise-status",
          ready: false,
          error: err && err.message ? err.message : String(err),
        });
      });
  }

  push(sample) {
    this.frame[this.offset++] = sample;
    if (this.offset < FRAME_SAMPLES) return;

    let denoised = false;
    if (this.rnnoiseEnabled && this.rnnoise) {
      this.rnnoise.processFrame480(this.frame, 0);
      this.rnnoise.processFrame480(this.frame, RNNOISE_FRAME_SAMPLES);
      denoised = true;
    }

    let sum = 0;
    for (let i = 0; i < FRAME_SAMPLES; i++) sum += this.frame[i] * this.frame[i];
    const frame = this.frame;
    this.frame = new Float32Array(FRAME_SAMPLES);
    this.offset = 0;
    this.port.postMessage(
      { samples: frame, rms: Math.sqrt(sum / FRAME_SAMPLES), denoised },
      [frame.buffer]
    );
  }

  process(inputs, outputs) {
    if (this.disposed) return false;
    const output = outputs[0] && outputs[0][0];
    if (output) output.fill(0);
    const channels = inputs[0];
    if (!channels || channels.length === 0) return true;

    // Downmix to mono.
    let input = channels[0];
    if (channels.length > 1) {
      input = new Float32Array(input.length);
      for (const ch of channels) for (let i = 0; i < input.length; i++) input[i] += ch[i] / channels.length;
    }

    if (this.ratio === 1) {
      for (let i = 0; i < input.length; i++) this.push(input[i]);
      return true;
    }
    // Linear interpolation resampler.
    const len = input.length;
    while (this.t < len - 1) {
      const i0 = Math.floor(this.t);
      const frac = this.t - i0;
      const a = i0 < 0 ? this.last : input[i0];
      const b = input[i0 + 1];
      this.push(a + (b - a) * frac);
      this.t += this.ratio;
    }
    this.t -= len;
    this.last = input[len - 1];
    return true;
  }
}

registerProcessor("ts6-mic-capture", Ts6MicCapture);