add stereo source support in EqualPowerPanner
https://bugs.webkit.org/show_bug.cgi?id=81092
Patch by Wei James <james.wei@intel.com> on 2012-04-11
Reviewed by Chris Rogers.
Source/WebCore:
Test: webaudio/panner-equalpower-stereo.html
* platform/audio/EqualPowerPanner.cpp:
(WebCore::EqualPowerPanner::pan):
LayoutTests:
* webaudio/panner-equalpower-stereo-expected.txt: Added.
* webaudio/panner-equalpower-stereo.html: Copied from LayoutTests/webaudio/panner-equalpower.html.
* webaudio/panner-equalpower.html:
* webaudio/resources/audio-testing.js:
(createStereoImpulseBuffer):
* webaudio/resources/panner-model-testing.js:
(createGraph):
(createTestAndRun):
(equalPowerGain):
(checkResult):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@113889 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/WebCore/platform/audio/EqualPowerPanner.cpp b/Source/WebCore/platform/audio/EqualPowerPanner.cpp
index a2d2dff..9035367 100644
--- a/Source/WebCore/platform/audio/EqualPowerPanner.cpp
+++ b/Source/WebCore/platform/audio/EqualPowerPanner.cpp
@@ -51,8 +51,8 @@
void EqualPowerPanner::pan(double azimuth, double /*elevation*/, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess)
{
- // FIXME: implement stereo sources
- bool isInputSafe = inputBus && inputBus->numberOfChannels() == 1 && framesToProcess <= inputBus->length();
+ unsigned numberOfInputChannels = inputBus->numberOfChannels();
+ bool isInputSafe = inputBus && (numberOfInputChannels == 1 || numberOfInputChannels == 2) && framesToProcess <= inputBus->length();
ASSERT(isInputSafe);
if (!isInputSafe)
return;
@@ -62,14 +62,14 @@
if (!isOutputSafe)
return;
- const AudioChannel* channel = inputBus->channel(0);
- const float* sourceP = channel->data();
+ 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 (!sourceP || !destinationL || !destinationR)
+
+ if (!sourceL || !sourceR || !destinationL || !destinationR)
return;
-
+
// Clamp azimuth to allowed range of -180 -> +180.
azimuth = max(-180.0, azimuth);
azimuth = min(180.0, azimuth);
@@ -80,35 +80,73 @@
azimuth = -180 - azimuth;
else if (azimuth > 90)
azimuth = 180 - azimuth;
-
- // Pan smoothly from left to right with azimuth going from -90 -> +90 degrees.
- double desiredPanPosition = (azimuth + 90) / 180;
- double desiredGainL = cos(0.5 * piDouble * desiredPanPosition);
- double desiredGainR = sin(0.5 * piDouble * desiredPanPosition);
+ double desiredPanPosition;
+ double desiredGainL;
+ double desiredGainR;
+ if (numberOfInputChannels == 1) { // For mono source case.
+ // Pan smoothly from left to right with azimuth going from -90 -> +90 degrees.
+ desiredPanPosition = (azimuth + 90) / 180;
+ } else { // For stereo source case.
+ if (azimuth <= 0) { // from -90 -> 0
+ // sourceL -> destL and "equal-power pan" sourceR as in mono case
+ // by transforming the "azimuth" value from -90 -> 0 degrees into the range -90 -> +90.
+ desiredPanPosition = (azimuth + 90) / 90;
+ } else { // from 0 -> +90
+ // sourceR -> destR and "equal-power pan" sourceL as in mono case
+ // by transforming the "azimuth" value from 0 -> +90 degrees into the range -90 -> +90.
+ desiredPanPosition = azimuth / 90;
+ }
+ }
+
+ desiredGainL = cos(0.5 * piDouble * desiredPanPosition);
+ desiredGainR = sin(0.5 * piDouble * desiredPanPosition);
+
// Don't de-zipper on first render call.
if (m_isFirstRender) {
m_isFirstRender = false;
m_gainL = desiredGainL;
m_gainR = desiredGainR;
}
-
+
// 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;
- while (n--) {
- float input = *sourceP++;
- gainL += (desiredGainL - gainL) * SmoothingConstant;
- gainR += (desiredGainR - gainR) * SmoothingConstant;
- *destinationL++ = static_cast<float>(input * gainL);
- *destinationR++ = static_cast<float>(input * gainR);
+ if (numberOfInputChannels == 1) { // For mono source case.
+ while (n--) {
+ float inputL = *sourceL++;
+ gainL += (desiredGainL - gainL) * SmoothingConstant;
+ gainR += (desiredGainR - gainR) * SmoothingConstant;
+ *destinationL++ = static_cast<float>(inputL * gainL);
+ *destinationR++ = static_cast<float>(inputL * gainR);
+ }
+ } else { // For stereo source case.
+ if (azimuth <= 0) { // from -90 -> 0
+ while (n--) {
+ float inputL = *sourceL++;
+ float inputR = *sourceR++;
+ gainL += (desiredGainL - gainL) * SmoothingConstant;
+ gainR += (desiredGainR - gainR) * SmoothingConstant;
+ *destinationL++ = static_cast<float>(inputL + inputR * gainL);
+ *destinationR++ = static_cast<float>(inputR * gainR);
+ }
+ } else { // from 0 -> +90
+ while (n--) {
+ float inputL = *sourceL++;
+ float inputR = *sourceR++;
+ gainL += (desiredGainL - gainL) * SmoothingConstant;
+ gainR += (desiredGainR - gainR) * SmoothingConstant;
+ *destinationL++ = static_cast<float>(inputL * gainL);
+ *destinationR++ = static_cast<float>(inputR + inputL * gainR);
+ }
+ }
}
m_gainL = gainL;
