add experimental support for audio data api

kripken · Jan 13, 2012 · d3131b8 · d3131b8
1 parent f62f0be
commit d3131b8
Showing 1 changed file with 67 additions and 22 deletions.
diff --git a/speakClient.js b/speakClient.js
@@ -1,32 +1,77 @@
 function speak(text, args) {
-  function encode64(data) {
-    var BASE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
-    var PAD = '=';
-    var ret = '';
-    var leftchar = 0;
-    var leftbits = 0;
-    for (var i = 0; i < data.length; i++) {
-      leftchar = (leftchar << 8) | data[i];
-      leftbits += 8;
-      while (leftbits >= 6) {
-        var curr = (leftchar >> (leftbits-6)) & 0x3f;
-        leftbits -= 6;
-        ret += BASE[curr];
+  function parseWav(wav) {
+    function readInt(i, bytes) {
+      var ret = 0;
+      var shft = 0;
+      while (bytes) {
+        ret += wav[i] << shft;
+        shft += 8;
+        i++;
+        bytes--;
       }
+      return ret;
     }
-    if (leftbits == 2) {
-      ret += BASE[(leftchar&3) << 4];
-      ret += PAD + PAD;
-    } else if (leftbits == 4) {
-      ret += BASE[(leftchar&0xf) << 2];
-      ret += PAD;
+    if (readInt(20, 2) != 1) throw 'Invalid compression code, not PCM';
+    if (readInt(22, 2) != 1) throw 'Invalid number of channels, not 1';
+    return {
+      sampleRate: readInt(24, 4),
+      bitsPerSample: readInt(34, 2),
+      samples: wav.subarray(44)
+    };
+  }
+
+  function playHTMLAudioElement(wav) {
+    function encode64(data) {
+      var BASE = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
+      var PAD = '=';
+      var ret = '';
+      var leftchar = 0;
+      var leftbits = 0;
+      for (var i = 0; i < data.length; i++) {
+        leftchar = (leftchar << 8) | data[i];
+        leftbits += 8;
+        while (leftbits >= 6) {
+          var curr = (leftchar >> (leftbits-6)) & 0x3f;
+          leftbits -= 6;
+          ret += BASE[curr];
+        }
+      }
+      if (leftbits == 2) {
+        ret += BASE[(leftchar&3) << 4];
+        ret += PAD + PAD;
+      } else if (leftbits == 4) {
+        ret += BASE[(leftchar&0xf) << 2];
+        ret += PAD;
+      }
+      return ret;
+    }
+
+    document.getElementById("audio").innerHTML=("<audio id=\"player\" src=\"data:audio/x-wav;base64,"+encode64(wav)+"\">");
+    document.getElementById("player").play();
+  }
+
+  function playAudioDataAPI(data) {
+    try {
+      var output = new Audio();
+      output.mozSetup(1, data.sampleRate);
+      var num = data.samples.length;
+      var buffer = data.samples;
+      var f32Buffer = new Float32Array(num);
+      for (var i = 0; i < num; i++) {
+        f32Buffer[i] = ((buffer[i<<1] + (buffer[(i<<1)+1]<<8))/65535)-1;
+      }
+      output.mozWriteAudio(f32Buffer);
+      return true;
+    } catch(e) {
+      return false;
     }
-    return ret;
   }
 
   var wav = generateSpeech(text, args);
+  var data = parseWav(wav); // validate the data and parse it
 
-  document.getElementById("audio").innerHTML=("<audio id=\"player\" src=\"data:audio/x-wav;base64,"+encode64(wav)+"\">");
-  document.getElementById("player").play();
+  if (1) { // !playAudioDataAPI(data)) {
+    playHTMLAudioElement(wav);
+  }
 }