1 files changed, 47 insertions, 0 deletions

diff --git a/projects/text_to_speech/utils.js b/projects/text_to_speech/utils.js
new file mode 100644
index 00000000..4f53dea8
--- /dev/null
+++ b/projects/text_to_speech/utils.js
@@ -0,0 +1,47 @@
+// Adapted from https://www.npmjs.com/package/audiobuffer-to-wav
+
+export function encodeWAV(samples) {
+    let offset = 44;
+    const buffer = new ArrayBuffer(offset + samples.length * 4);
+    const view = new DataView(buffer);
+    const sampleRate = 16000;
+
+    /* RIFF identifier */
+    writeString(view, 0, 'RIFF')
+    /* RIFF chunk length */
+    view.setUint32(4, 36 + samples.length * 4, true)
+    /* RIFF type */
+    writeString(view, 8, 'WAVE')
+    /* format chunk identifier */
+    writeString(view, 12, 'fmt ')
+    /* format chunk length */
+    view.setUint32(16, 16, true)
+    /* sample format (raw) */
+    view.setUint16(20, 3, true)
+    /* channel count */
+    view.setUint16(22, 1, true)
+    /* sample rate */
+    view.setUint32(24, sampleRate, true)
+    /* byte rate (sample rate * block align) */
+    view.setUint32(28, sampleRate * 4, true)
+    /* block align (channel count * bytes per sample) */
+    view.setUint16(32, 4, true)
+    /* bits per sample */
+    view.setUint16(34, 32, true)
+    /* data chunk identifier */
+    writeString(view, 36, 'data')
+    /* data chunk length */
+    view.setUint32(40, samples.length * 4, true)
+
+    for (let i = 0; i < samples.length; ++i, offset += 4) {
+        view.setFloat32(offset, samples[i], true)
+    }
+
+    return buffer
+}
+
+function writeString(view, offset, string) {
+    for (let i = 0; i < string.length; ++i) {
+        view.setUint8(offset + i, string.charCodeAt(i))
+    }
+}
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