Support sample rates up to 384 kHz.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 235 matching lines @@
         // Arbitrarly limit the maximum length to 1 million frames (about 20 sec
         // at 48kHz).  The number of buckets is fairly arbitrary.
         DEFINE_STATIC_LOCAL(CustomCountHistogram, audioBufferLengthHistogram,
             ("WebAudio.AudioBuffer.Length", 1, 1000000, 50));
         // The limits are the min and max AudioBuffer sample rates currently
         // supported.  We use explicit values here instead of
         // AudioUtilities::minAudioBufferSampleRate() and
         // AudioUtilities::maxAudioBufferSampleRate().  The number of buckets is
         // fairly arbitrary.
         DEFINE_STATIC_LOCAL(CustomCountHistogram, audioBufferSampleRateHistogram,
-            ("WebAudio.AudioBuffer.SampleRate", 3000, 192000, 60));
+            ("WebAudio.AudioBuffer.SampleRate384k", 3000, 384000, 60));
 
         audioBufferChannelsHistogram.sample(numberOfChannels);
         audioBufferLengthHistogram.count(numberOfFrames);
         audioBufferSampleRateHistogram.count(sampleRate);
 
         // Compute the ratio of the buffer rate and the context rate so we know
         // how often the buffer needs to be resampled to match the context.  For
         // the histogram, we multiply the ratio by 100 and round to the nearest
         // integer.  If the context is closed, don't record this because we
         // don't have a sample rate for closed context.
         if (!isContextClosed()) {
-            // The limits are choosen from 100*(3000/192000) = 1.5625 and
-            // 100*(192000/3000) = 6400, where 3000 and 192000 are the current
+            // The limits are choosen from 100*(3000/384000) = 0.78125 and
+            // 100*(384000/3000) = 12800, where 3000 and 384000 are the current
             // min and max sample rates possible for an AudioBuffer.  The number
             // of buckets is fairly arbitrary.
             DEFINE_STATIC_LOCAL(CustomCountHistogram, audioBufferSampleRateRatioHistogram,
-                ("WebAudio.AudioBuffer.SampleRateRatio", 1, 6400, 50));
+                ("WebAudio.AudioBuffer.SampleRateRatio384K", 0, 12800, 50));

[Mark P, 2016/09/15 23:16:31]

Min of histogram should always be "1".  There will always be a "underflow"
bucket to catch 0s (and negative values) that's not included in the min.

[Raymond Toy, 2016/10/10 16:28:32]

Done.

             float ratio = 100 * sampleRate / this->sampleRate();
             audioBufferSampleRateRatioHistogram.count(static_cast<int>(0.5 + ratio));
         }
     }
 
     return buffer;
 }
 
 ScriptPromise BaseAudioContext::decodeAudioData(ScriptState* scriptState, DOMArrayBuffer* audioData, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback, ExceptionState& exceptionState)
 {
@@ skipping 555 matching lines @@
 
 SecurityOrigin* BaseAudioContext::getSecurityOrigin() const
 {
     if (getExecutionContext())
         return getExecutionContext()->getSecurityOrigin();
 
     return nullptr;
 }
 
 } // namespace blink