Merge pull request #90 from HamStudy/feature/TypedArraySupport

Feature/typed array support

www/audioInputCapture.js

@@ -21,6 +21,8 @@ var exec = require('cordova/exec');
 
 var audioinput = {};
 
+var hasTypedArrays = 'Int16Array' in window && 'Float32Array' in window;
+
 // Audio formats
 audioinput.FORMAT = {
     PCM_16BIT: 'PCM_16BIT',
@@ -364,13 +366,29 @@ audioinput._audioInputDebugEvent = function (debugMessage) {
 };
 
 /**
- * Normalize audio input
- *
- * @param {Object} pcmData
- * @private
+ * Returns a typed array, normalizing if needed
+ * @param {number[]} pcmData - Array of short integers which came from the plugin
  */
-audioinput._normalizeAudio = function (pcmData) {
+function normalizeToTyped(pcmData) {
+    if (audioinput._cfg.normalize) {
+        var out = Float32Array.from(pcmData, function(i) {
+            return parseFloat(i) / audioinput._cfg.normalizationFactor;
+        });
+        // If last value is NaN, remove it.
+        if (isNaN(out.subarray[out.length - 1])) {
+            return out.subarray(0, out.length - 1);
+        }
+        return out;
+    }
+
+    return Int16Array.from(pcmData);
+}
 
+/**
+ * Returns a standard javascript array, normalizing if needed
+ * @param {number[]} pcmData - Array of short integers which came from the plugin
+ */
+function normalizeNoTyped (pcmData) {
     if (audioinput._cfg.normalize) {
         for (var i = 0; i < pcmData.length; i++) {
             pcmData[i] = parseFloat(pcmData[i]) / audioinput._cfg.normalizationFactor;
@@ -383,7 +401,22 @@ audioinput._normalizeAudio = function (pcmData) {
     }
 
     return pcmData;
-};
+}
+
+/**
+ * Normalize audio input
+ * 
+ * If typed arrays are supported by the browser then a Float32Array will be returned
+ * if nomalization is enabled; if not then a Int16Array will be returned. These are
+ * much more efficient to work with since you can get subarrays without copying them.
+ * If typed arrays are not supported then a normal array will be returned
+ *
+ * @param {Object} pcmData
+ * @private
+ * 
+ * @returns {Int16Array|Float32Array|Array} 
+ */
+audioinput._normalizeAudio = hasTypedArrays ? normalizeToTyped : normalizeNoTyped;
 
 
 /**