Index: Source/platform/audio/StereoPanner.cpp |
diff --git a/Source/platform/audio/StereoPanner.cpp b/Source/platform/audio/StereoPanner.cpp |
new file mode 100644 |
index 0000000000000000000000000000000000000000..7eaa17253df532902aa83f6437b9dc7ca20fb5bd |
--- /dev/null |
+++ b/Source/platform/audio/StereoPanner.cpp |
@@ -0,0 +1,159 @@ |
+// Copyright 2014 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#include "config.h" |
+ |
+#if ENABLE(WEB_AUDIO) |
+ |
+#include "platform/audio/StereoPanner.h" |
+ |
+#include "platform/audio/AudioBus.h" |
+#include "platform/audio/AudioUtilities.h" |
+#include "wtf/MathExtras.h" |
+#include <algorithm> |
+ |
+// Use a 50ms smoothing / de-zippering time-constant. |
+const float SmoothingTimeConstant = 0.050f; |
+ |
+namespace blink { |
+ |
+StereoPanner::StereoPanner(float sampleRate) : Spatializer(PanningModelEqualPower) |
+ , m_isFirstRender(true) |
+ , m_gainL(0.5) |
+ , m_gainR(0.5) |
+{ |
+ m_smoothingConstant = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate); |
+} |
+ |
+void StereoPanner::panWithSampleAccurateValues(const AudioBus* inputBus, AudioBus* outputBus, const float* panValues, size_t framesToProcess) |
+{ |
+ bool isInputSafe = inputBus |
+ && (inputBus->numberOfChannels() == 1 || inputBus->numberOfChannels() == 2) |
+ && framesToProcess <= inputBus->length(); |
+ ASSERT(isInputSafe); |
+ if (!isInputSafe) |
+ return; |
+ |
+ unsigned numberOfInputChannels = inputBus->numberOfChannels(); |
+ |
+ bool isOutputSafe = outputBus |
+ && outputBus->numberOfChannels() == 2 |
+ && framesToProcess <= outputBus->length(); |
+ ASSERT(isOutputSafe); |
+ if (!isOutputSafe) |
+ return; |
+ |
+ const float* sourceL = inputBus->channel(0)->data(); |
+ const float* sourceR = numberOfInputChannels > 1 ? inputBus->channel(1)->data() : sourceL; |
+ float* destinationL = outputBus->channelByType(AudioBus::ChannelLeft)->mutableData(); |
+ float* destinationR = outputBus->channelByType(AudioBus::ChannelRight)->mutableData(); |
+ |
+ if (!sourceL || !sourceR || !destinationL || !destinationR) |
+ return; |
+ |
+ // Cache in local variables. |
+ double gainL = m_gainL; |
+ double gainR = m_gainR; |
+ |
+ int n = framesToProcess; |
+ |
+ if (numberOfInputChannels == 1) { // For mono source case. |
+ while (n--) { |
+ float inputL = *sourceL++; |
+ float panValue = clampTo(*panValues++, -1.0, 1.0); |
+ float panPosition = (panValue * 0.5 + 0.5) * piOverTwoDouble; |
+ gainL = std::cos(panPosition); |
+ gainR = std::sin(panPosition); |
+ *destinationL++ = static_cast<float>(inputL * gainL); |
+ *destinationR++ = static_cast<float>(inputL * gainR); |
+ } |
+ } else { // For stereo source case. |
+ while (n--) { |
+ float inputL = *sourceL++; |
+ float inputR = *sourceR++; |
+ float panValue = clampTo(*panValues++, -1.0, 1.0); |
+ float panPosition = (panValue * 0.5 + 0.5) * piOverTwoDouble; |
+ gainL = std::cos(panPosition); |
+ gainR = std::sin(panPosition); |
+ *destinationL++ = static_cast<float>(inputL * gainL); |
+ *destinationR++ = static_cast<float>(inputR * gainR); |
+ } |
+ } |
+ |
+ m_gainL = gainL; |
+ m_gainR = gainR; |
+} |
+ |
+void StereoPanner::panToTargetValue(const AudioBus* inputBus, AudioBus* outputBus, float panValue, size_t framesToProcess) |
+{ |
+ bool isInputSafe = inputBus |
+ && (inputBus->numberOfChannels() == 1 || inputBus->numberOfChannels() == 2) |
+ && framesToProcess <= inputBus->length(); |
+ ASSERT(isInputSafe); |
+ if (!isInputSafe) |
+ return; |
+ |
+ unsigned numberOfInputChannels = inputBus->numberOfChannels(); |
+ |
+ bool isOutputSafe = outputBus |
+ && outputBus->numberOfChannels() == 2 |
+ && framesToProcess <= outputBus->length(); |
+ ASSERT(isOutputSafe); |
+ if (!isOutputSafe) |
+ return; |
+ |
+ const float* sourceL = inputBus->channel(0)->data(); |
+ const float* sourceR = numberOfInputChannels > 1 ? inputBus->channel(1)->data() : sourceL; |
+ float* destinationL = outputBus->channelByType(AudioBus::ChannelLeft)->mutableData(); |
+ float* destinationR = outputBus->channelByType(AudioBus::ChannelRight)->mutableData(); |
+ |
+ if (!sourceL || !sourceR || !destinationL || !destinationR) |
+ return; |
+ |
+ float panValueClamped = clampTo(panValue, -1.0, 1.0); |
+ double targetGainL = std::cos(piOverTwoDouble * (panValueClamped * 0.5 + 0.5)); |
+ double targetGainR = std::sin(piOverTwoDouble * (panValueClamped * 0.5 + 0.5)); |
+ |
+ // Don't de-zipper on first render call. |
+ if (m_isFirstRender) { |
+ m_isFirstRender = false; |
+ m_gainL = targetGainL; |
+ m_gainR = targetGainR; |
+ } |
+ |
+ // Cache in local variables. |
+ double gainL = m_gainL; |
+ double gainR = m_gainR; |
+ |
+ // Get local copy of smoothing constant. |
+ const double SmoothingConstant = m_smoothingConstant; |
+ |
+ int n = framesToProcess; |
+ |
+ if (numberOfInputChannels == 1) { // For mono source case. |
+ while (n--) { |
+ float inputL = *sourceL++; |
+ gainL += (targetGainL - gainL) * SmoothingConstant; |
+ gainR += (targetGainR - gainR) * SmoothingConstant; |
+ *destinationL++ = static_cast<float>(inputL * gainL); |
+ *destinationR++ = static_cast<float>(inputL * gainR); |
+ } |
+ } else { // For stereo source case. |
+ while (n--) { |
+ float inputL = *sourceL++; |
+ float inputR = *sourceR++; |
+ gainL += (targetGainL - gainL) * SmoothingConstant; |
+ gainR += (targetGainR - gainR) * SmoothingConstant; |
+ *destinationL++ = static_cast<float>(inputL * gainL); |
+ *destinationR++ = static_cast<float>(inputR * gainR); |
+ } |
+ } |
+ |
+ m_gainL = gainL; |
+ m_gainR = gainR; |
+} |
+ |
+} // namespace blink |
+ |
+#endif // ENABLE(WEB_AUDIO) |