Revert 260913 "Revert of Tighten up webrtc audio tests. (https:/..."

> Revert of Tighten up webrtc audio tests. (https://codereview.chromium.org/216523003/)
> 
> Reason for revert:
> This might have resulted in some flaky tests.  This failure happened two builds after the patch landed.
> 
> http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%282%29/builds/10598
> 
> See bug for more details.
> 
> BUG=358759
> 
> Original issue's description:
> > Tighten up webrtc audio tests.
> > 
> > See http://goo.gl/LDae10. I'm trying to improve this algorithm. We used to
> > check that some value was high enough and that the average was in the right
> > ballpark. The new algorithm will count falling edges in the peaks instead,
> > as a means to detect the peaks in the audio signal. The algorithm reliably
> > yields one peak per second of sampled audio, which is correct because the
> > audio signal beeps at 1 Hz. To get some margin, I'm sampling four seconds
> > and checking that I get at least two peaks, which should be a rock solid 
> > assumption even on slow machines.
> > 
> > BUG=357287,357626
> > R=perkj@chromium.org
> > NOTRY=True
> > (passed all trybots, just got stuck on a broken win trybot)
> > 
> > Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=260878
> 
> TBR=perkj@chromium.org,phoglund@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> BUG=357287,357626
> 
> Review URL: https://codereview.chromium.org/220403006

TBR=rlarocque@chromium.org

Review URL: https://codereview.chromium.org/217423019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261104 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 28 insertions, 24 deletions

diff --git a/content/test/data/media/peerconnection-call.html b/content/test/data/media/peerconnection-call.html
index 2327647..57658fa 100644
--- a/content/test/data/media/peerconnection-call.html
+++ b/content/test/data/media/peerconnection-call.html
@@ -63,7 +63,7 @@
     waitForVideo('remote-view-2');
   }
 
-  // Test that we can setup call with an audio and video track and check that 
+  // Test that we can setup call with an audio and video track and check that
   // the video resolution is as expected.
   function callAndExpectResolution(constraints,
                                    expected_width,
@@ -308,8 +308,8 @@
     // Wait until we have gathered samples and can conclude if audio is playing.
     addExpectedEvent();
     var onCallEstablished = function() {
-      gatherAudioLevelSamples(gSecondConnection, 300, 100,
-                              function(samples) {
+      // Gather 50 samples per second for 2 seconds.
+      gatherAudioLevelSamples(gSecondConnection, 100, 50, function(samples) {
         verifyAudioIsPlaying(samples);
         eventOccured();
       });
@@ -329,7 +329,7 @@
       enableRemoteAudio(gSecondConnection, false);
 
       setTimeout(function() {
-        gatherAudioLevelSamples(gSecondConnection, 200, 100, function(samples) {
+        gatherAudioLevelSamples(gSecondConnection, 100, 50, function(samples) {
           verifyIsSilent(samples);
           reportTestSuccess();
         });
@@ -348,11 +348,11 @@
       }, 500);
 
       setTimeout(function() {
-        gatherAudioLevelSamples(gSecondConnection, 200, 100, function(samples) {
+        gatherAudioLevelSamples(gSecondConnection, 100, 50, function(samples) {
           verifyAudioIsPlaying(samples);
           reportTestSuccess();
         });
-      }, 1000);
+      }, 1500);
     });
   }
 
diff --git a/content/test/data/media/webrtc_test_audio.js b/content/test/data/media/webrtc_test_audio.js
index 40668c6..52c7d38 100644
--- a/content/test/data/media/webrtc_test_audio.js
+++ b/content/test/data/media/webrtc_test_audio.js
@@ -4,6 +4,9 @@
 
 // Audio test utilities.
 
+// GetStats reports audio output energy in the [0, 32768] range.
+var MAX_AUDIO_OUTPUT_ENERGY = 32768;
+
 // Gathers |numSamples| samples at |frequency| number of times per second and
 // calls back |callback| with an array with numbers in the [0, 32768] range.
 function gatherAudioLevelSamples(peerConnection, numSamples, frequency,
@@ -22,28 +25,29 @@ function gatherAudioLevelSamples(peerConnection, numSamples, frequency,
   }, 1000 / frequency);
 }
 
-// Tries to identify the beep-every-second signal generated by the fake audio
-// media/audio/fake_audio_input_stream.cc. Fails the test if we can't see a
-// signal.
+// Tries to identify the beep-every-half-second signal generated by the fake
+// audio device in media/video/capture/fake_video_capture_device.cc. Fails the
+// test if we can't see a signal. The samples should have been gathered over at
+// least two seconds since we expect to see at least three "peaks" in there
+// (we should see either 3 or 4 depending on how things line up).
 function verifyAudioIsPlaying(samples) {
-  var average = 0;
-  for (var i = 0; i < samples.length; ++i)
-    average += samples[i] / samples.length;
+  var numPeaks = 0;
+  var threshold = MAX_AUDIO_OUTPUT_ENERGY * 0.7;
+  var currentlyOverThreshold = false;
 
-  var largest = 0;
-  for (var i = 0; i < samples.length; ++i)
-    largest = Math.max(largest, samples[i]);
+  // Detect when we have been been over the threshold and is going back again
+  // (i.e. count peaks). We should see about one peak per second.
+  for (var i = 0; i < samples.length; ++i) {
+    if (currentlyOverThreshold && samples[i] < threshold)
+      numPeaks++;
+    currentlyOverThreshold = samples[i] >= threshold;
+  }
 
-  console.log('Average audio level: ' + average + ', largest: ' + largest);
+  console.log('Number of peaks identified: ' + numPeaks);
 
-  // TODO(phoglund): Make a more sophisticated curve-fitting algorithm. We want
-  // to see a number of peaks with relative silence between them. The following
-  // seems to work fine on a nexus 7.
-  if (average < 3000 || average > 8000)
-    failTest('Unexpected avg audio level: got ' + average + ', expected it ' +
-             'to be 4000 < avg < 8000.');
-  if (largest < 25000)
-    failTest('Too low max audio level: got ' + largest + ', expected > 30000.');
+  if (numPeaks < 2)
+    failTest('Expected to see at least two peaks in audio signal, got ' +
+        numPeaks + '. Dumping samples for analysis: "' + samples + '"');
 }
 
 // If silent (like when muted), we should get very near zero audio level.