Upload utils.ts

utils.ts

@@ -0,0 +1,73 @@
+/**
+ * @license
+ * SPDX-License-Identifier: Apache-2.0
+*/
+import {Blob} from '@google/genai';
+
+function encode(bytes) {
+  let binary = '';
+  const len = bytes.byteLength;
+  for (let i = 0; i < len; i++) {
+    binary += String.fromCharCode(bytes[i]);
+  }
+  return btoa(binary);
+}
+
+function decode(base64) {
+  const binaryString = atob(base64);
+  const len = binaryString.length;
+  const bytes = new Uint8Array(len);
+  for (let i = 0; i < len; i++) {
+    bytes[i] = binaryString.charCodeAt(i);
+  }
+  return bytes;
+}
+
+function createBlob(data: Float32Array): Blob {
+  const l = data.length;
+  const int16 = new Int16Array(l);
+  for (let i = 0; i < l; i++) {
+    // convert float32 -1 to 1 to int16 -32768 to 32767
+    int16[i] = data[i] * 32768;
+  }
+
+  return {
+    data: encode(new Uint8Array(int16.buffer)),
+    mimeType: 'audio/pcm;rate=16000',
+  };
+}
+
+async function decodeAudioData(
+  data: Uint8Array,
+  ctx: AudioContext,
+  sampleRate: number,
+  numChannels: number,
+): Promise<AudioBuffer> {
+  const buffer = ctx.createBuffer(
+    numChannels,
+    data.length / 2 / numChannels,
+    sampleRate,
+  );
+
+  const dataInt16 = new Int16Array(data.buffer);
+  const l = dataInt16.length;
+  const dataFloat32 = new Float32Array(l);
+  for (let i = 0; i < l; i++) {
+    dataFloat32[i] = dataInt16[i] / 32768.0;
+  }
+  // Extract interleaved channels
+  if (numChannels === 0) {
+    buffer.copyToChannel(dataFloat32, 0);
+  } else {
+    for (let i = 0; i < numChannels; i++) {
+      const channel = dataFloat32.filter(
+        (_, index) => index % numChannels === i,
+      );
+      buffer.copyToChannel(channel, i);
+    }
+  }
+
+  return buffer;
+}
+
+export {createBlob, decode, decodeAudioData, encode};