use bufferFrom instead of Buffer.from to support old environments.

Fixes #55

Author: nfriedly

package.json

@@ -49,11 +49,12 @@
     "webpack": "^2.2.1"
   },
   "dependencies": {
+    "buffer-from": "^0.1.1",
     "clone": "^2.1.0",
     "defaults": "^1.0.3",
     "get-user-media-promise": "^1.1.0",
     "lodash.pullallwith": "^4.7.0",
-    "microphone-stream": "^3.0.5",
+    "microphone-stream": "^3.0.8",
     "nodeify-fetch": "^1.0.1",
     "object.assign": "^4.0.4",
     "object.pick": "^1.2.0",

speech-to-text/webaudio-l16-stream.js

@@ -2,6 +2,8 @@
 var Transform = require('stream').Transform;
 var util = require('util');
 var defaults = require('defaults');
+// some versions of the buffer browser lib don't support Buffer.from (such as the one included by the current version of express-browserify)
+var bufferFrom = require('buffer-from');
 
 var TARGET_SAMPLE_RATE = 16000;
 /**
@@ -151,9 +153,9 @@ WebAudioL16Stream.prototype.floatTo16BitPCM = function(input) {
   var output = new DataView(new ArrayBuffer(input.length * 2)); // length is in bytes (8-bit), so *2 to get 16-bit length
   for (var i = 0; i < input.length; i++) {
     var multiplier = input[i] < 0 ? 0x8000 : 0x7fff; // 16-bit signed range is -32768 to 32767
-    output.setInt16(i * 2, (input[i] * multiplier) | 0, true); // index, value, little edian
+    output.setInt16(i * 2, (input[i] * multiplier) | 0, true); // index, value ("| 0" = convert to 32-bit int, round towards 0), littleEndian.
   }
-  return Buffer.from(output.buffer);
+  return bufferFrom(output.buffer);
 };
 
 /**