AudioParam must support k-rate processing with audio-rate connections

https://bugs.webkit.org/show_bug.cgi?id=94385

Reviewed by Kenneth Russell.

Fully implement AudioParam *final* value calculation according to spec:
https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#AudioParam

In particular, this covers the case where the parameter is k-rate, and we also
have audio-rate connections to the AudioParam.

* Modules/webaudio/AudioParam.cpp:
(WebCore::AudioParam::finalValue):
(WebCore):
(WebCore::AudioParam::calculateSampleAccurateValues):
(WebCore::AudioParam::calculateFinalValues):
* Modules/webaudio/AudioParam.h:
(AudioParam):
* Modules/webaudio/DelayDSPKernel.cpp:
(WebCore::DelayDSPKernel::process):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@125957 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog

@@ -1,3 +1,26 @@
+2012-08-17  Chris Rogers  <crogers@google.com>
+
+        AudioParam must support k-rate processing with audio-rate connections
+        https://bugs.webkit.org/show_bug.cgi?id=94385
+
+        Reviewed by Kenneth Russell.
+
+        Fully implement AudioParam *final* value calculation according to spec:
+        https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html#AudioParam
+
+        In particular, this covers the case where the parameter is k-rate, and we also
+        have audio-rate connections to the AudioParam.
+
+        * Modules/webaudio/AudioParam.cpp:
+        (WebCore::AudioParam::finalValue):
+        (WebCore):
+        (WebCore::AudioParam::calculateSampleAccurateValues):
+        (WebCore::AudioParam::calculateFinalValues):
+        * Modules/webaudio/AudioParam.h:
+        (AudioParam):
+        * Modules/webaudio/DelayDSPKernel.cpp:
+        (WebCore::DelayDSPKernel::process):
+
 2012-08-17  Alice Cheng  <alice_cheng@apple.com>
 
         Preserve styling elements in DeleteSelectionCommand

Source/WebCore/Modules/webaudio/AudioParam.cpp

@@ -94,38 +94,44 @@ bool AudioParam::smooth()
     return false;
 }
 
+float AudioParam::finalValue()
+{
+    float value;
+    calculateFinalValues(&value, 1, false);
+    return value;
+}
+
 void AudioParam::calculateSampleAccurateValues(float* values, unsigned numberOfValues)
 {
     bool isSafe = context() && context()->isAudioThread() && values && numberOfValues;
     ASSERT(isSafe);
     if (!isSafe)
         return;
 
-    if (numberOfRenderingConnections())
-        calculateAudioRateSignalValues(values, numberOfValues);
-    else
-        calculateTimelineValues(values, numberOfValues);
+    calculateFinalValues(values, numberOfValues, true);
 }
 
-void AudioParam::calculateAudioRateSignalValues(float* values, unsigned numberOfValues)
+void AudioParam::calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate)
 {
-    bool isGood = numberOfRenderingConnections() && numberOfValues;
+    bool isGood = context() && context()->isAudioThread() && values && numberOfValues;
     ASSERT(isGood);
     if (!isGood)
         return;
 
     // The calculated result will be the "intrinsic" value summed with all audio-rate connections.
 
-    if (m_timeline.hasValues()) {
-        // Calculate regular timeline values, if we have any.
+    if (sampleAccurate) {
+        // Calculate sample-accurate (a-rate) intrinsic values.
         calculateTimelineValues(values, numberOfValues);
     } else {
-        // Otherwise set values array to our constant value.
-        float value = m_value; // Cache in local.
+        // Calculate control-rate (k-rate) intrinsic value.
+        bool hasValue;
+        float timelineValue = m_timeline.valueForContextTime(context(), narrowPrecisionToFloat(m_value), hasValue);
+
+        if (hasValue)
+            m_value = timelineValue;
 
-        // FIXME: can be optimized if we create a new VectorMath function.
-        for (unsigned i = 0; i < numberOfValues; ++i)
-            values[i] = value;
+        values[0] = narrowPrecisionToFloat(m_value);
     }
 
     // Now sum all of the audio-rate connections together (unity-gain summing junction).
@@ -138,7 +144,7 @@ void AudioParam::calculateAudioRateSignalValues(float* values, unsigned numberOf
         ASSERT(output);
 
         // Render audio from this output.
-        AudioBus* connectionBus = output->pull(0, numberOfValues);
+        AudioBus* connectionBus = output->pull(0, AudioNode::ProcessingSizeInFrames);
 
         // Sum, with unity-gain.
         summingBus.sumFrom(*connectionBus);

Source/WebCore/Modules/webaudio/AudioParam.h

@@ -56,9 +56,14 @@ class AudioParam : public AudioSummingJunction, public RefCounted<AudioParam> {
     virtual bool canUpdateState() OVERRIDE { return true; }
     virtual void didUpdate() OVERRIDE { }
 
+    // Intrinsic value.
     float value();
     void setValue(float);
 
+    // Final value for k-rate parameters, otherwise use calculateSampleAccurateValues() for a-rate.
+    // Must be called in the audio thread.
+    float finalValue();
+
     String name() const { return m_name; }
 
     float minValue() const { return static_cast<float>(m_minValue); }
@@ -112,7 +117,8 @@ class AudioParam : public AudioSummingJunction, public RefCounted<AudioParam> {
     }
 
 private:
-    void calculateAudioRateSignalValues(float* values, unsigned numberOfValues);
+    // sampleAccurate corresponds to a-rate (audio rate) vs. k-rate in the Web Audio specification.
+    void calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate);
     void calculateTimelineValues(float* values, unsigned numberOfValues);
 
     String m_name;

Source/WebCore/Modules/webaudio/DelayDSPKernel.cpp

@@ -99,7 +99,7 @@ void DelayDSPKernel::process(const float* source, float* destination, size_t fra
         return;
 
     float sampleRate = this->sampleRate();
-    double delayTime = delayProcessor() ? delayProcessor()->delayTime()->value() : m_desiredDelayFrames / sampleRate;
+    double delayTime = delayProcessor() ? delayProcessor()->delayTime()->finalValue() : m_desiredDelayFrames / sampleRate;
 
     // Make sure the delay time is in a valid range.
     delayTime = min(maxDelayTime(), delayTime);