1 files changed, 62 insertions, 0 deletions
diff --git a/dom/media/webaudio/PanningUtils.h b/dom/media/webaudio/PanningUtils.h
new file mode 100644
index 0000000000..eef8ae78c9
--- /dev/null
+++ b/dom/media/webaudio/PanningUtils.h
@@ -0,0 +1,62 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef PANNING_UTILS_H
+#define PANNING_UTILS_H
+
+#include "AudioSegment.h"
+#include "AudioNodeEngine.h"
+
+namespace mozilla::dom {
+
+template <typename T>
+void GainMonoToStereo(const AudioBlock& aInput, AudioBlock* aOutput, T aGainL,
+                      T aGainR) {
+  float* outputL = aOutput->ChannelFloatsForWrite(0);
+  float* outputR = aOutput->ChannelFloatsForWrite(1);
+  const float* input = static_cast<const float*>(aInput.mChannelData[0]);
+
+  MOZ_ASSERT(aInput.ChannelCount() == 1);
+  MOZ_ASSERT(aOutput->ChannelCount() == 2);
+
+  AudioBlockPanMonoToStereo(input, aGainL, aGainR, outputL, outputR);
+}
+
+// T can be float or an array of float, and  U can be bool or an array of bool,
+// depending if the value of the parameters are constant for this block.
+template <typename T, typename U>
+void GainStereoToStereo(const AudioBlock& aInput, AudioBlock* aOutput, T aGainL,
+                        T aGainR, U aOnLeft) {
+  float* outputL = aOutput->ChannelFloatsForWrite(0);
+  float* outputR = aOutput->ChannelFloatsForWrite(1);
+  const float* inputL = static_cast<const float*>(aInput.mChannelData[0]);
+  const float* inputR = static_cast<const float*>(aInput.mChannelData[1]);
+
+  MOZ_ASSERT(aInput.ChannelCount() == 2);
+  MOZ_ASSERT(aOutput->ChannelCount() == 2);
+
+  AudioBlockPanStereoToStereo(inputL, inputR, aGainL, aGainR, aOnLeft, outputL,
+                              outputR);
+}
+
+// T can be float or an array of float, and  U can be bool or an array of bool,
+// depending if the value of the parameters are constant for this block.
+template <typename T, typename U>
+void ApplyStereoPanning(const AudioBlock& aInput, AudioBlock* aOutput, T aGainL,
+                        T aGainR, U aOnLeft) {
+  aOutput->AllocateChannels(2);
+
+  if (aInput.ChannelCount() == 1) {
+    GainMonoToStereo(aInput, aOutput, aGainL, aGainR);
+  } else {
+    GainStereoToStereo(aInput, aOutput, aGainL, aGainR, aOnLeft);
+  }
+  aOutput->mVolume = aInput.mVolume;
+}
+
+}  // namespace mozilla::dom
+
+#endif  // PANNING_UTILS_H