Add new PyAuto test for measuring audio tag latency.

Values seem stable around ~55ms locally. Will monitor on the bots to see if we need to add some additional loops. BUG=128615 TEST=This fabulous new test! Review URL: https://chromiumcodereview.appspot.com/10411007 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138184 0039d316-1c4b-4281-b951-d872f2087c98

Add new PyAuto test for measuring audio tag latency.
Values seem stable around ~55ms locally. Will monitor on the bots to see if we need to add some additional loops. BUG=128615 TEST=This fabulous new test! Review URL: https://chromiumcodereview.appspot.com/10411007 git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138184 0039d316-1c4b-4281-b951-d872f2087c98
b8591e1c · dalecurtis@google.com · cbadb28a · b8591e1c · b8591e1c · b8591e1c
Commit b8591e1c authored May 22, 2012 by dalecurtis@google.com
4 changed files
--- a/chrome/test/data/media/html/audio_latency_perf.html
+++ b/chrome/test/data/media/html/audio_latency_perf.html
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Audio Loop Benchmark</title>
+    <style>* { font-family: monospace; }</style>
+  </head>
+  <body>
+    <h1>Audio Loop Benchmark</h1>
+    <p>
+      Benchmark measuring how fast we can continuously repeat a short sound
+      clip. In the ideal scenario we'd have zero latency processing script,
+      seeking back to the beginning of the clip, and resuming audio playback.
+    </p>
+
+    <button onclick="startTest();">Start</button>
+
+    <p>
+      Times Played: <span id="times"></span></span><br>
+      Clip Duration: <span id="clip"></span></span><br>
+      Ideal Duration: <span id="ideal"></span><br>
+      Actual Duration: <span id="actual"></span><br>
+      Average Latency: <span id="average"></span><br>
+    </p>
+
+    <script>
+      var TIMES = 50, averageLatency = 0;
+
+      function getAndClearElement(id) {
+        var elem = document.getElementById(id);
+        elem.innerText = '';
+        return elem;
+      }
+
+      function startTest() {
+        var timesElem = getAndClearElement('times');
+        var clipElem = getAndClearElement('clip');
+        var idealElem = getAndClearElement('ideal');
+        var actualElem = getAndClearElement('actual');
+        var averageElem = getAndClearElement('average');
+        var buttonElem = document.querySelector('button');
+
+        var loopCount = 0, idealDuration = 0, actualDuration = 0;
+        var startTime;
+
+        buttonElem.disabled = true;
+
+        function onLoaded() {
+          idealDuration = Math.round(audio.duration * TIMES * 1000, 0);
+          idealElem.innerText =  idealDuration + ' ms';
+          clipElem.innerText = Math.round(audio.duration * 1000, 0) + ' ms';
+          audio.addEventListener('seeked', onLoop);
+          startTime = window.performance.webkitNow();
+          audio.play();
+        }
+
+        var audio = document.createElement('audio');
+        audio.addEventListener('canplaythrough', onLoaded);
+        audio.loop = true;
+        audio.src = '../pink_noise_140ms.wav';
+
+        function onLoop() {
+          ++loopCount;
+          timesElem.innerText = loopCount + '/' + TIMES;
+          if (loopCount == TIMES) {
+            actualDuration = window.performance.webkitNow() - startTime;
+            actualElem.innerText = actualDuration + ' ms';
+            buttonElem.disabled = false;
+
+            averageLatency = (actualDuration - idealDuration) / loopCount;
+            averageElem.innerText = averageLatency + ' ms';
+
+            // Let the PyAuto test know we're done testing.
+            if (window.domAutomationController)
+              window.domAutomationController.send(true);
+
+            audio.pause();
+          }
+        }
+      }
+    </script>
+  </body>
+</html>
--- a/chrome/test/data/media/pink_noise_140ms.wav
+++ b/chrome/test/data/media/pink_noise_140ms.wav
--- a/chrome/test/functional/PYAUTO_TESTS
+++ b/chrome/test/functional/PYAUTO_TESTS
@@ -726,6 +726,7 @@
  # HTML5 media performance tests.
  'AV_PERF': {
     'linux': [
+       'media.audio_latency_perf',
       'media.media_constrained_network_perf',
       'media.media_stat_perf',
       'media.media_seek_perf',

--- a/chrome/test/functional/media/audio_latency_perf.py
+++ b/chrome/test/functional/media/audio_latency_perf.py
+#!/usr/bin/env python
+# Copyright (c) 2012 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.
+
+"""Audio latency performance test.
+
+Benchmark measuring how fast we can continuously repeat a short sound clip.  In
+the ideal scenario we'd have zero latency processing script, seeking back to the
+beginning of the clip, and resuming audio playback.
+
+Performance is recorded as the average latency of N playbacks.  I.e., if we play
+a clip 50 times and the ideal duration of all playbacks is 1000ms and the total
+duration is 1500ms, the recorded result is (1500ms - 1000ms) / 50 == 10ms.
+"""
+import os
+
+import pyauto_media
+import pyauto_utils
+import pyauto
+
+
+# HTML test path; relative to src/chrome/test/data.
+_TEST_HTML_PATH = os.path.join('media', 'html', 'audio_latency_perf.html')
+
+
+class AudioLatencyPerfTest(pyauto.PyUITest):
+  """PyAuto test container.  See file doc string for more information."""
+
+  def testAudioLatency(self):
+    """Launches HTML test which runs the audio latency test."""
+    self.NavigateToURL(self.GetFileURLForDataPath(_TEST_HTML_PATH))
+
+    # Block until the test finishes and notifies us.
+    self.assertTrue(self.ExecuteJavascript('startTest();'))
+    latency = float(self.GetDOMValue('averageLatency'))
+    pyauto_utils.PrintPerfResult('audio_latency', 'latency', latency, 'ms')
+
+
+if __name__ == '__main__':
+  pyauto_media.Main()