Move utility functions for sample rate to AudioUtilities.

Source/platform/audio/HRTFPanner.cpp

Index: Source/platform/audio/HRTFPanner.cpp
diff --git a/Source/platform/audio/HRTFPanner.cpp b/Source/platform/audio/HRTFPanner.cpp
index 851410a61a04a0459d6627280bdf565679a45b5d..bef6ed00290673d2b83e557a6755fd9a87b7c362 100644
--- a/Source/platform/audio/HRTFPanner.cpp
+++ b/Source/platform/audio/HRTFPanner.cpp
@@ -54,10 +54,10 @@ HRTFPanner::HRTFPanner(float sampleRate, HRTFDatabaseLoader* databaseLoader)
     , m_elevation2(0)
     , m_crossfadeX(0)
     , m_crossfadeIncr(0)
-    , m_convolverL1(fftSizeForSampleRate(sampleRate))
-    , m_convolverR1(fftSizeForSampleRate(sampleRate))
-    , m_convolverL2(fftSizeForSampleRate(sampleRate))
-    , m_convolverR2(fftSizeForSampleRate(sampleRate))
+    , m_convolverL1(AudioUtilities::fftSizeForSampleRate(sampleRate))
+    , m_convolverR1(AudioUtilities::fftSizeForSampleRate(sampleRate))
+    , m_convolverL2(AudioUtilities::fftSizeForSampleRate(sampleRate))
+    , m_convolverR2(AudioUtilities::fftSizeForSampleRate(sampleRate))
     , m_delayLineL(MaxDelayTimeSeconds, sampleRate)
     , m_delayLineR(MaxDelayTimeSeconds, sampleRate)
     , m_tempL1(RenderingQuantum)
@@ -72,25 +72,6 @@ HRTFPanner::~HRTFPanner()
 {
 }
 
-size_t HRTFPanner::fftSizeForSampleRate(float sampleRate)
-{
-    // The HRTF impulse responses (loaded as audio resources) are 512 sample-frames @44.1KHz.
-    // Currently, we truncate the impulse responses to half this size,
-    // but an FFT-size of twice impulse response size is needed (for convolution).
-    // So for sample rates around 44.1KHz an FFT size of 512 is good.
-    // For different sample rates, the truncated response is resampled.
-    // The resampled length is used to compute the FFT size by choosing a power of two that is
-    // greater than or equal the resampled length. This power of two is doubled to get the actual FFT size.
-
-    ASSERT(sampleRate >= 3000 && sampleRate <= 192000);
-
-    int truncatedImpulseLength = 256;
-    double sampleRateRatio = sampleRate / 44100;
-    double resampledLength = truncatedImpulseLength * sampleRateRatio;
-
-    return 2 * (1 << static_cast<unsigned>(log2(resampledLength)));
-}
-
 void HRTFPanner::reset()
 {
     m_convolverL1.reset();