Clamp AudioParam automations to the nominal range.

third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 319 matching lines @@
 
     // Remove all events starting at startTime.
     for (unsigned i = 0; i < m_events.size(); ++i) {
         if (m_events[i].time() >= startTime) {
             m_events.remove(i, m_events.size() - i);
             break;
         }
     }
 }
 
-float AudioParamTimeline::valueForContextTime(AudioDestinationHandler& audioDestination, float defaultValue, bool& hasValue)
+float AudioParamTimeline::valueForContextTime(AudioDestinationHandler& audioDestination, float defaultValue, bool& hasValue, float minValue, float maxValue)
 {
     {
         MutexTryLocker tryLocker(m_eventsLock);
         if (!tryLocker.locked() || !m_events.size() || audioDestination.currentTime() < m_events[0].time()) {
             hasValue = false;
             return defaultValue;
         }
     }
 
     // Ask for just a single value.
     float value;
     double sampleRate = audioDestination.sampleRate();
     size_t startFrame = audioDestination.currentSampleFrame();
     double controlRate = sampleRate / AudioHandler::ProcessingSizeInFrames; // one parameter change per render quantum
-    value = valuesForFrameRange(startFrame, startFrame + 1, defaultValue, &value, 1, sampleRate, controlRate);
+    value = valuesForFrameRange(startFrame, startFrame + 1, defaultValue, &value, 1, sampleRate, controlRate, minValue, maxValue);
 
     hasValue = true;
     return value;
 }
 
 float AudioParamTimeline::valuesForFrameRange(
     size_t startFrame,
     size_t endFrame,
     float defaultValue,
     float* values,
     unsigned numberOfValues,
     double sampleRate,
-    double controlRate)
+    double controlRate,
+    float minValue,
+    float maxValue)
 {
     // We can't contend the lock in the realtime audio thread.
     MutexTryLocker tryLocker(m_eventsLock);
     if (!tryLocker.locked()) {
         if (values) {
             for (unsigned i = 0; i < numberOfValues; ++i)
                 values[i] = defaultValue;
         }
         return defaultValue;
     }

[hongchan, 2016/06/17 17:00:40]

Sorry to bring this up again, why this pattern is different form the line
342~348? This mutex is active until this method is finished.

[Raymond Toy, 2016/06/17 17:10:05]

I didn't actually change this.  Are you saying I should?

[hongchan, 2016/06/17 17:55:06]

Disregard my comment. They are different, but looks okay here.

 
-    return valuesForFrameRangeImpl(startFrame, endFrame, defaultValue, values, numberOfValues, sampleRate, controlRate);
+    float lastValue = valuesForFrameRangeImpl(startFrame, endFrame, defaultValue, values, numberOfValues, sampleRate, controlRate);
+
+    // Clamp the values now to the nominal range
+    for (unsigned k = 0; k < numberOfValues; ++k)
+        values[k] = clampTo(values[k], minValue, maxValue);
+
+    return lastValue;

[hongchan, 2016/06/17 17:00:40]

Are these safe outside of tryLock?

[Raymond Toy, 2016/06/17 17:10:05]

I didn't really change the thread safety here.  It should be as safe (or unsafe)
as before.

[hongchan, 2016/06/17 17:55:06]

I misundstood the scope of tryLock. This looks safe.

 }
 
 float AudioParamTimeline::valuesForFrameRangeImpl(
     size_t startFrame,
     size_t endFrame,
     float defaultValue,
     float* values,
     unsigned numberOfValues,
     double sampleRate,
     double controlRate)
@@ skipping 525 matching lines @@
     for (; writeIndex < numberOfValues; ++writeIndex)
         values[writeIndex] = value;
 
     // This value is used to set the .value attribute of the AudioParam.  it should be the last
     // computed value.
     return values[numberOfValues - 1];
 }
 
 } // namespace blink