Plays PCM data via Audio Data API or Web Audio API

examples/inspector/inspector.html

@@ -14,6 +14,7 @@
     <script src="../../lib/DataView.js/DataView.js"></script>
     <script src="../../lib/Kanvas/kanvas.js"></script>
     <script src="../../lib/xstats/xstats.js"></script>
+    <script src="../../lib/mp3/mp3.js"></script>
 
     <!-- Load SWF Dependencies -->
     <script src="../../src/swf/util.js"></script>

lib/mp3/mp3.js

@@ -0,0 +1 @@
+// placeholder for MP3Decoder class

src/flash/display/Loader.js

@@ -3,6 +3,7 @@ var LoaderDefinition = (function () {
   var LOADER_PATH = 'flash/display/Loader.js';
   var WORKER_SCRIPTS = [
     '../../../lib/DataView.js/DataView.js',
+    '../../../lib/mp3/mp3.js',
 
     '../util.js',
 

src/flash/media/Sound.js

@@ -1,9 +1,17 @@
+var PLAY_USING_AUDIO_TAG = true;
+
 var SoundDefinition = (function () {
 
   var audioElement = null;
 
   function getAudioDescription(soundData, onComplete) {
     audioElement = audioElement || document.createElement('audio');
+    if (!audioElement.canPlayType(soundData.mimeType)) {
+      onComplete({
+        duration: 0
+      });
+      return;
+    }
     audioElement.src = "data:" + soundData.mimeType + ";base64," + base64ArrayBuffer(soundData.data);
     audioElement.load();
     audioElement.addEventListener("loadedmetadata", function () {
@@ -23,8 +31,19 @@ var SoundDefinition = (function () {
       this._id3 = new flash.media.ID3Info();
 
       var s = this.symbol;
-      if (s && s.packaged) {
-        var soundData = s.packaged;
+      if (s) {
+        var soundData = {};
+        if (s.pcm) {
+          soundData.sampleRate = s.sampleRate;
+          soundData.channels = s.channels;
+          soundData.pcm = s.pcm;
+          soundData.end = s.pcm.length;
+        }
+        soundData.completed = true;
+        if (s.packaged) {
+          soundData.data = s.packaged.data.buffer;
+          soundData.mimeType = s.packaged.mimeType;
+        }
         var _this = this;
         getAudioDescription(soundData, function (description) {
           _this._length = description.duration;
@@ -48,27 +67,68 @@ var SoundDefinition = (function () {
       }
 
       var _this = this;
-      var loader = this._loader = new flash.net.URLLoader(request);
-      loader.dataFormat = "binary";
+      var stream = this._stream = new flash.net.URLStream();
+      var ByteArrayClass = avm2.systemDomain.getClass("flash.utils.ByteArray");
+      var data = ByteArrayClass.createInstance();
+      var dataPosition = 0;
+      var mp3DecodingSession = null;
+      var soundData = { completed: false };
 
-      loader.addEventListener("progress", function (event) {
+      stream.addEventListener("progress", function (event) {
         console.info("PROGRESS");
+        _this._bytesLoaded = event.public$bytesLoaded;
+        _this._bytesTotal = event.public$bytesTotal;
+
+        if (!PLAY_USING_AUDIO_TAG && !mp3DecodingSession) {
+          // initialize MP3 decoding
+          mp3DecodingSession = decodeMP3(soundData, function ondurationchanged(duration) {
+            if (_this._length === 0) {
+              // once we have some data, trying to play it
+              _this._soundData = soundData;
+
+              _this._playQueue.forEach(function (item) {
+                item.channel._playSoundDataViaChannel(soundData, item.startTime);
+              });
+            }
+            // TODO estimate duration based on bytesTotal
+            _this._length = duration * 1000;
+          });
+        }
+
+        var bytesAvailable = stream.bytesAvailable;
+        stream.readBytes(data, dataPosition, bytesAvailable);
+        if (mp3DecodingSession) {
+          mp3DecodingSession.pushData(data, dataPosition, bytesAvailable);
+        }
+        dataPosition += bytesAvailable;
+
         _this.dispatchEvent(event);
       });
 
-      loader.addEventListener("complete", function (event) {
+      stream.addEventListener("complete", function (event) {
         _this.dispatchEvent(event);
-        var soundData = _this._soundData = {
-          data: loader.data.a,
-          mimeType: 'audio/mpeg'
-        };
-        getAudioDescription(soundData, function (description) {
-          _this._length = description.duration;
-        });
-        _this._playQueue.forEach(function (item) {
-          playChannel(soundData, item.channel, item.startTime, item.soundTransform);
-        });
+        soundData.data = data.a;
+        soundData.mimeType = 'audio/mpeg';
+        soundData.completed = true;
+
+        if (PLAY_USING_AUDIO_TAG) {
+          _this._soundData = soundData;
+
+          getAudioDescription(soundData, function (description) {
+            _this._length = description.duration;
+          });
+
+          _this._playQueue.forEach(function (item) {
+            item.channel._playSoundDataViaAudio(soundData, item.startTime);
+          });
+        }
+
+        if (mp3DecodingSession) {
+          mp3DecodingSession.close();
+        }
       });
+
+      stream.load(request);
     },
     loadCompressedDataFromByteArray: function loadCompressedDataFromByteArray(bytes, bytesLength) {
       throw 'Not implemented: loadCompressedDataFromByteArray';
@@ -82,22 +142,25 @@ var SoundDefinition = (function () {
       startTime = startTime || 0;
       var channel = new flash.media.SoundChannel();
       channel._sound = this;
+      channel._soundTransform = soundTransform;
       this._playQueue.push({
         channel: channel,
-        startTime: startTime,
-        soundTransform: soundTransform
+        startTime: startTime
       });
       if (this._soundData) {
-        playChannel(this._soundData, channel, startTime, soundTransform);
+        if (PLAY_USING_AUDIO_TAG)
+          channel._playSoundDataViaAudio(this._soundData, startTime);
+        else
+          channel._playSoundDataViaChannel(this._soundData, startTime);
       }
       return channel;
     },
 
     get bytesLoaded() {
-      return this._loader.bytesLoaded;
+      return this._bytesLoaded;
     },
     get bytesTotal() {
-      return this._loader.bytesTotal;
+      return this._bytesTotal;
     },
     get id3() {
       return this._id3;
@@ -116,13 +179,59 @@ var SoundDefinition = (function () {
     }
   };
 
-  function playChannel(soundData, channel, startTime, soundTransform) {
-    var element = channel._element;
-    element.src = "data:" + soundData.mimeType + ";base64," + base64ArrayBuffer(soundData.data);
-    element.addEventListener("loadeddata", function loaded() {
-      element.currentTime = startTime / 1000;
-      element.play();
-    });
+  // TODO send to MP3 decoding worker
+  function decodeMP3(soundData, ondurationchanged) {
+    var currentSize = 8000;
+    var pcm = new Float32Array(currentSize);
+    var position = 0;
+    var mp3Decoder = new MP3Decoder();
+    mp3Decoder.onframedata = function (frame, channels, sampleRate) {
+      if (frame.length === 0)
+        return;
+      if (!position) {
+        // first data: initializes pcm data fields
+        soundData.sampleRate = sampleRate,
+        soundData.channels = channels;
+        soundData.pcm = pcm;
+      }
+      if (position + frame.length >= currentSize) {
+        do {
+          currentSize *= 2;
+        } while (position + frame.length >= currentSize);
+        var newPcm = new Float32Array(currentSize);
+        newPcm.set(pcm);
+        pcm = soundData.pcm = newPcm;
+      }
+      pcm.set(frame, position);
+      soundData.end = position += frame.length;
+
+      var duration = position / soundData.sampleRate / soundData.channels;
+      ondurationchanged(duration);
+    };
+    return  {
+      chunks: [],
+      pushData: function (data, offset, length) {
+        function decodeNext() {
+          var chunk = chunks.shift();
+          mp3Decoder.push(chunk);
+          if (chunks.length > 0)
+            setTimeout(decodeNext);
+        }
+        var chunks = this.chunks;
+        var initPush = chunks.length === 0;
+        var maxChunkLength = 8000;
+        for (var i = 0; i < length; i += maxChunkLength) {
+          var chunkOffset = offset + i;
+          var chunkLength = Math.min(length - chunkOffset, maxChunkLength);
+          var chunk = new Uint8Array(data.a, chunkOffset, chunkLength);
+          chunks.push(chunk);
+        }
+        if (initPush)
+          decodeNext();
+      },
+      close: function () {
+      }
+    };
   }
 
   var desc = Object.getOwnPropertyDescriptor;

src/flash/media/SoundChannel.js

@@ -2,7 +2,56 @@ const SoundChannelDefinition = (function () {
   return {
     // ()
     initialize: function () {
-      this._element = document.createElement('audio');
+      this._element = null;
+      this._position = 0;
+      this._pcmData = null;
+      this._soundTransform = null;
+    },
+    _playSoundDataViaChannel: function (soundData, startTime) {
+      assert(soundData.pcm, 'no pcm data found');
+
+      var self = this;
+      var position = Math.round(startTime / 1000 * soundData.sampleRate) *
+                     soundData.channels;
+      this._position = startTime;
+      this._audioChannel = createAudioChannel(soundData.sampleRate, soundData.channels);
+      this._audioChannel.ondatarequested = function (e) {
+        var end = soundData.end;
+        if (position >= end && soundData.completed) {
+          // end of buffer
+          self._audioChannel.stop();
+          return;
+        }
+        // TODO loop
+
+        var count = Math.min(end - position, e.count);
+        if (count === 0) return;
+
+        var data = e.data;
+        var source = soundData.pcm;
+        for (var j = 0; j < count; j++) {
+          data[j] = source[position++];
+        }
+
+        self._position = position / soundData.sampleRate / soundData.channels * 1000;
+      };
+      this._audioChannel.start();
+    },
+    _playSoundDataViaAudio: function (soundData, startTime) {
+      this._position = startTime;
+      var self = this;
+      var element = document.createElement('audio');
+      if (!element.canPlayType(soundData.mimeType))
+        error('\"' + soundData.mimeType + '\" type playback is not supported by the browser');
+      element.src = "data:" + soundData.mimeType + ";base64," + base64ArrayBuffer(soundData.data);
+      element.addEventListener("loadeddata", function loaded() {
+        element.currentTime = startTime / 1000;
+        element.play();
+      });
+      element.addEventListener("timeupdate", function timeupdate() {
+        self._position = element.currentTime * 1000;
+      });
+      this._element = element;
     },
     __glue__: {
       native: {
@@ -11,12 +60,25 @@ const SoundChannelDefinition = (function () {
         instance: {
           // (void) -> void
           stop: function stop() {
-            this._element.pause();
+            if (this._element) {
+              this._element.pause();
+            }
+            if (this._audioChannel) {
+              this._audioChannel.stop();
+            }
           },
           "position": {
             // (void) -> Number
             get: function position() {
-              return this._element.currentTime * 1000;
+              return this._position;
+            }
+          },
+          "soundTransform": {
+            get: function soundTransform() {
+              return this._soundTransform;
+            },
+            set: function soundTransform(val) {
+              this._soundTransform = val;
             }
           }
         }
@@ -24,3 +86,181 @@ const SoundChannelDefinition = (function () {
     }
   };
 }).call(this);
+
+function createAudioChannel(sampleRate, channels) {
+  if (WebAudioChannel.isSupported)
+    return new WebAudioChannel(sampleRate, channels);
+  else if (AudioDataChannel.isSupported)
+    return new AudioDataChannel(sampleRate, channels);
+  else
+    error('PCM data playback is not supported by the browser');
+}
+
+// Resample sound using linear interpolation for Web Audio due to
+// http://code.google.com/p/chromium/issues/detail?id=73062
+function AudioResampler(sourceRate, targetRate) {
+  this.sourceRate = sourceRate;
+  this.targetRate = targetRate;
+  this.tail = [];
+  this.sourceOffset = 0;
+}
+AudioResampler.prototype = {
+  ondatarequested: function (e) { },
+  getData: function (channelsData, count) {
+    var k = this.sourceRate / this.targetRate;
+
+    var offset = this.sourceOffset;
+    var needed = Math.ceil((count - 1) * k + offset) + 1;
+    var sourceData = [];
+    for (var channel = 0; channel < channelsData.length; channel++)
+      sourceData.push(new Float32Array(needed));
+    var e = { data: sourceData, count: needed };
+    this.ondatarequested(e);
+    for (var channel = 0; channel < channelsData.length; channel++) {
+      var data = channelsData[channel];
+      var source = sourceData[channel];
+      for (var j = 0; j < count; j++) {
+        var i = j * k + offset;
+        var i1 = Math.floor(i), i2 = Math.ceil(i);
+        var source_i1 = i1 < 0 ? this.tail[channel] : source[i1];
+        if (i1 === i2) {
+          data[j] = source_i1;
+        } else {
+          var alpha = i - i1;
+          data[j] = source_i1 * (1 - alpha) + source[i2] * alpha;
+        }
+      }
+      this.tail[channel] = source[needed - 1];
+    }
+    this.sourceOffset = ((count - 1) * k + offset) - (needed - 1);
+  }
+};
+
+function WebAudioChannel(sampleRate, channels) {
+  var context = WebAudioChannel.context;
+  if (!context) {
+    if (typeof AudioContext !== 'undefined')
+      context = new AudioContext();
+    else
+      context = new webkitAudioContext();
+    WebAudioChannel.context = context;
+  }
+  this.context = context;
+  this.contextSampleRate = context.sampleRate || 44100;
+
+  this.channels = channels;
+  this.sampleRate = sampleRate;
+  if (this.contextSampleRate != sampleRate) {
+    this.resampler = new AudioResampler(sampleRate, this.contextSampleRate);
+    this.resampler.ondatarequested = function (e) {
+      this.requestData(e.data, e.count);
+    }.bind(this);
+  }
+}
+WebAudioChannel.prototype = {
+  start: function () {
+    var source = this.context.createScriptProcessor ?
+      this.context.createScriptProcessor(2048, 0, this.channels) :
+      this.context.createJavaScriptNode(2048, 0, this.channels);
+    var self = this;
+    source.onaudioprocess = function(e) {
+      var channelsData = [];
+      for (var i = 0; i < self.channels; i++)
+        channelsData.push(e.outputBuffer.getChannelData(i));
+      var count = channelsData[0].length;
+      if (self.resampler) {
+        self.resampler.getData(channelsData, count);
+      } else {
+        var e = { data: channelsData, count: count };
+        self.requestData(channelsData, count);
+      }
+    };
+
+    source.connect(this.context.destination);
+    this.source = source;
+  },
+  stop: function () {
+    this.source.disconnect(this.context.destination);
+  },
+  requestData: function (channelsData, count) {
+    var channels = this.channels;
+    var buffer = new Float32Array(count * channels);
+    var e = { data: buffer, count: buffer.length };
+    this.ondatarequested(e);
+
+    for (var j = 0, p = 0; j < count; j++) {
+      for (var i = 0; i < channels; i++)
+        channelsData[i][j] = buffer[p++];
+    }
+  }
+};
+WebAudioChannel.isSupported = (function() {
+  return typeof AudioContext !== 'undefined' ||
+         typeof webkitAudioContext != 'undefined';
+})();
+
+// from https://wiki.mozilla.org/Audio_Data_API
+function AudioDataChannel(sampleRate, channels) {
+  this.sampleRate = sampleRate;
+  this.channels = channels;
+}
+AudioDataChannel.prototype = {
+  start: function () {
+    var sampleRate = this.sampleRate;
+    var channels = this.channels;
+    var self = this;
+
+    // Initialize the audio output.
+    var audio = new Audio();
+    audio.mozSetup(channels, sampleRate);
+
+    var currentWritePosition = 0;
+    var prebufferSize = sampleRate * channels / 2; // buffer 500ms
+    var tail = null, tailPosition;
+
+    // The function called with regular interval to populate
+    // the audio output buffer.
+    this.interval = setInterval(function() {
+      var written;
+      // Check if some data was not written in previous attempts.
+      if(tail) {
+        written = audio.mozWriteAudio(tail.subarray(tailPosition));
+        currentWritePosition += written;
+        tailPosition += written;
+        if(tailPosition < tail.length) {
+          // Not all the data was written, saving the tail...
+          return; // ... and exit the function.
+        }
+        tail = null;
+      }
+
+      // Check if we need add some data to the audio output.
+      var currentPosition = audio.mozCurrentSampleOffset();
+      var available = currentPosition + prebufferSize - currentWritePosition;
+      available -= available % channels; // align to channels count
+      if(available > 0) {
+        // Request some sound data from the callback function.
+        var soundData = new Float32Array(available);
+        self.requestData(soundData, available);
+
+        // Writting the data.
+        written = audio.mozWriteAudio(soundData);
+        if(written < soundData.length) {
+          // Not all the data was written, saving the tail.
+          tail = soundData;
+          tailPosition = written;
+        }
+        currentWritePosition += written;
+      }
+    }, 100);
+  },
+  stop: function () {
+    clearInterval(this.interval);
+  },
+  requestData: function (data, count) {
+    this.ondatarequested({data: data, count: count});
+  }
+};
+AudioDataChannel.isSupported = (function () {
+  return 'mozSetup' in (new Audio);
+})();

src/swf/sound.js

@@ -63,7 +63,7 @@ function defineSound(tag, dictionary) {
   case SOUND_FORMAT_PCM_BE:
     if (tag.soundSize == SOUND_SIZE_16_BIT) {
       for (var i = 0, j = 0; i < pcm.length; i++, j += 2)
-        pcm[i] = ((data[i] << 24) | (data[i + 1] << 16)) / 2147483648;
+        pcm[i] = ((data[j] << 24) | (data[j + 1] << 16)) / 2147483648;
       packaged = packageWave(data, sampleRate, channels, 16, true);
     } else {
       for (var i = 0; i < pcm.length; i++)
@@ -74,7 +74,7 @@ function defineSound(tag, dictionary) {
   case SOUND_FORMAT_PCM_LE:
     if (tag.soundSize == SOUND_SIZE_16_BIT) {
       for (var i = 0, j = 0; i < pcm.length; i++, j += 2)
-        pcm[i] = ((data[i + 1] << 24) | (data[i] << 16)) / 2147483648;
+        pcm[i] = ((data[j + 1] << 24) | (data[j] << 16)) / 2147483648;
       packaged = packageWave(data, sampleRate, channels, 16, false);
     } else {
       for (var i = 0; i < pcm.length; i++)
@@ -153,7 +153,7 @@ function SwfSoundStream_decode_PCM(data) {
 function SwfSoundStream_decode_PCM_be(data) {
   var pcm = new Float32Array(data.length / 2);
   for (var i = 0, j = 0; i < pcm.length; i++, j += 2)
-    pcm[i] = ((data[i] << 24) | (data[i + 1] << 16)) / 2147483648;
+    pcm[i] = ((data[j] << 24) | (data[j + 1] << 16)) / 2147483648;
   this.currentSample += pcm.length / this.channels;
   return {
     pcm: pcm,
@@ -164,7 +164,7 @@ function SwfSoundStream_decode_PCM_be(data) {
 function SwfSoundStream_decode_PCM_le(data) {
   var pcm = new Float32Array(data.length / 2);
   for (var i = 0, j = 0; i < pcm.length; i++, j += 2)
-    pcm[i] = ((data[i + 1] << 24) | (data[i] << 16)) / 2147483648;
+    pcm[i] = ((data[j + 1] << 24) | (data[j] << 16)) / 2147483648;
   this.currentSample += pcm.length / this.channels;
   return {
     pcm: pcm,