Add VAD and keyword spotting for the Node package with WebAssembly (#1286)

wasm/nodejs/sherpa-onnx-wave.js

@@ -0,0 +1,57 @@
+// return an object
+// {
+//   samples: a float32 array
+//   sampleRate: an integer
+// }
+function readWave(filename, Module) {
+  const filenameLen = Module.lengthBytesUTF8(filename) + 1;
+  const pFilename = Module._malloc(filenameLen);
+  Module.stringToUTF8(filename, pFilename, filenameLen);
+
+  const w = Module._SherpaOnnxReadWave(pFilename);
+  Module._free(pFilename);
+
+
+  const samplesPtr = Module.HEAP32[w / 4] / 4;
+  const sampleRate = Module.HEAP32[w / 4 + 1];
+  const numSamples = Module.HEAP32[w / 4 + 2];
+
+  const samples = new Float32Array(numSamples);
+  for (let i = 0; i < numSamples; i++) {
+    samples[i] = Module.HEAPF32[samplesPtr + i];
+  }
+
+  Module._SherpaOnnxFreeWave(w);
+
+
+  return {samples: samples, sampleRate: sampleRate};
+}
+
+// data is an object
+// {
+//   samples: a float32 array
+//   sampleRate: an integer
+// }
+function writeWave(filename, data, Module) {
+  const pSamples =
+      Module._malloc(data.samples.length * data.samples.BYTES_PER_ELEMENT);
+  Module.HEAPF32.set(data.samples, pSamples / data.samples.BYTES_PER_ELEMENT);
+
+  const filenameLen = Module.lengthBytesUTF8(filename) + 1;
+  const pFilename = Module._malloc(filenameLen);
+  Module.stringToUTF8(filename, pFilename, filenameLen);
+
+  Module._SherpaOnnxWriteWave(
+      pSamples, data.samples.length, data.sampleRate, pFilename);
+
+  Module._free(pFilename);
+  Module._free(pSamples);
+}
+
+if (typeof process == 'object' && typeof process.versions == 'object' &&
+    typeof process.versions.node == 'string') {
+  module.exports = {
+    readWave,
+    writeWave,
+  };
+}