add manual clear of audio input array

tests/audio.js

@@ -20,7 +20,6 @@ const config = {
  * Note that transcription is limited to 60 seconds audio.
  * Use a GCS file for audio longer than 1 minute.
  */
-let audio;
 
 async function transcribeSpeech (audio) {
   const request = {
@@ -54,30 +53,81 @@ const ia = new portAudio.AudioIO({
 });
 ia.setEncoding('base64');
 ia.start();
-ia.on('error', (e) => {
-    console.log('error recording audio', + e);
-});
 ia.on('data', (chunk) => {
-
     const buf = Buffer.from(chunk, 'base64');
     audioInput.push(buf);
 });
 
+const ao = new portAudio.AudioIO({
+    outOptions: {
+        sampleFormat: 16,
+            channelCount: 1,
+        sampleRate: 16000,
+        deviceId: -1,
+        closeOnError: false,
+    }
+});
+ao.start();
+
 async function processAudio() {
 
     const buf = Buffer.concat(audioInput);
+    play(audioInput);
 
-    audioInput = [];
+    while(audioInput.length) { audioInput.pop() };
 
    transcribeSpeech({
        content: buf
    });
 }
 
+
+ function play(input) {
+    let i = 0;
+    // format buffers into half their size to account for writable highwaterMark.
+    const audio = bufSplit(input);
+    // call this fuction after last audio chunk has been written.
+    const callback = () => {
+        // TODO: clear portAudio writable buffer on write end.
+    }
+    write();
+    // iterate through audio array and write buffers to portAudio writable.
+    function write() {
+        let chunk;
+        let ok = true;
+        do {
+            chunk = audio[i];
+            if (i === audio.length - 1) {
+                // write last chunk.
+                ao.write(chunk, null, callback);
+            } else {
+                // check for backpreassure.
+                ok = ao.write(chunk, null);
+            }
+            i++;
+        } while (i < audio.length && ok);
+
+        if (i < audio.length) {
+            // Had to stop early!
+            // Write some more once it drains.
+            ao.once('drain', write);
+        }
+    }
+}
+
+// utility function used by play func
+function bufSplit(input){
+    let result = [];
+    input.forEach((b) => {
+        // split buffer into two.
+        result.push(b.slice(0, b.length / 2), b.slice(b.length / 2, b.length));
+    });
+    return result;
+}
+
 setTimeout(async () => {
     ia.pause();
     processAudio();
-    // ia.resume();
 }, 3000);
 
 setTimeout(() => {
@@ -87,7 +137,6 @@ setTimeout(() => {
 setTimeout(async () => {
     ia.pause();
     processAudio();
-    // ia.resume();
 }, 8000);
 
 setTimeout(() => {