Use frames instead of time for running AudioParam timelines.

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

 /*
  * Copyright (C) 2010 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 141 matching lines @@
         AudioBus* connectionBus = output->pull(0, AudioHandler::ProcessingSizeInFrames);
 
         // Sum, with unity-gain.
         summingBus->sumFrom(*connectionBus);
     }
 }
 
 void AudioParamHandler::calculateTimelineValues(float* values, unsigned numberOfValues)
 {
     // Calculate values for this render quantum.  Normally numberOfValues will
     // equal to AudioHandler::ProcessingSizeInFrames (the render quantum size).

[hongchan, 2015/09/30 22:14:18]

Wouldn't it be better to have comments like: Using frame over second to avoid
rounding-off error.

[Raymond Toy, 2015/09/30 22:30:18]

You want to add a comment that we're using frames instead of seconds?

[hongchan, 2015/09/30 22:47:59]

Yes, it might be confusing inside of some other contexts. Just to be clear.

[Raymond Toy, 2015/10/01 18:05:55]

Since we're renaming valuesForTimeRange to valuesForFrameRange, I think it's
pretty clear
we want frames now instead of seconds.

     double sampleRate = context()->sampleRate();
-    double startTime = context()->currentTime();
-    double endTime = startTime + numberOfValues / sampleRate;
+    size_t startFrame = context()->currentSampleFrame();
+    size_t endFrame = startFrame + numberOfValues;
 
     // Note we're running control rate at the sample-rate.
     // Pass in the current value as default value.
-    m_value = m_timeline.valuesForTimeRange(startTime, endTime, narrowPrecisionToFloat(m_value), values, numberOfValues, sampleRate, sampleRate);
+    m_value = m_timeline.valuesForTimeRange(startFrame, endFrame, narrowPrecisionToFloat(m_value), values, numberOfValues, sampleRate, sampleRate);

[hongchan, 2015/09/30 22:14:18]

In my opinion, the method name with the word 'TimeRange' seems to expect the
arguments as second. WDYT?

[Raymond Toy, 2015/09/30 22:30:18]

Renaming to valuesForFrameRange is fine with me.

[hongchan, 2015/09/30 22:47:59]

I think there are few other methods named with "TimeRange", so if we decide to
change this then we'll have to deal with the rest as well. Do you think it's
worth it? The word "FrameRange" is very clear to me though.

[Raymond Toy, 2015/10/01 18:05:55]

I've renamed it everywhere, more or less.

 }
 
 void AudioParamHandler::connect(AudioNodeOutput& output)
 {
     ASSERT(deferredTaskHandler().isGraphOwner());
 
     if (m_outputs.contains(&output))
         return;
 
     output.addParam(*this);
@@ skipping 71 matching lines @@
 }
 
 void AudioParam::cancelScheduledValues(double startTime, ExceptionState& exceptionState)
 {
     handler().timeline().cancelScheduledValues(startTime, exceptionState);
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)