Sub-sample accurate start of OscillatorNode

third_party/WebKit/LayoutTests/webaudio/resources/audit-util.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 /**
  * @fileOverview  This file includes legacy utility functions for the layout
  *                test.
  */
 
@@ skipping 239 matching lines @@
     var startFrame = timeToSampleFrame(grainOffset, sampleRate);
     var endFrame = timeToSampleFrame(grainOffset + duration, sampleRate);
 
     return endFrame - startFrame;
 }
 
 // True if the number is not an infinity or NaN
 function isValidNumber(x) {
     return !isNaN(x) && (x != Infinity) && (x != -Infinity);
 }
+
+// Compute the (linear) signal-to-noise ratio between |actual| and
+// |expected|.  The result is NOT in dB!  If the |actual| and
+// |expected| have different lengths, the shorter length is used.
+function computeSNR(actual, expected) {
+    var signalPower = 0;
+    var noisePower = 0;
+
+    var length = Math.min(actual.length, expected.length);
+
+    for (var k = 0; k < length; ++k) {
+        var diff = actual[k] - expected[k];
+        signalPower += expected[k] * expected[k];
+        noisePower += diff * diff;
+    }
+
+    return signalPower / noisePower;
+}