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/*
Copyright 2018 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS-IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "dsp/stereo_panner.h"
#include <cmath>
#include "base/constants_and_types.h"
namespace vraudio {
const float kStereoLeftRadians = kRadiansFromDegrees * kStereoLeftDegrees;
const float kStereoRightRadians = kRadiansFromDegrees * kStereoRightDegrees;
void CalculateStereoPanGains(const SphericalAngle& source_direction,
std::vector<float>* stereo_gains) {
// Note this applies the same panning law as was applied by the ambisonic
// equivalent panner to ensure consistency.
DCHECK(stereo_gains);
stereo_gains->resize(kNumStereoChannels);
const float cos_direction_elevation = std::cos(source_direction.elevation());
(*stereo_gains)[0] =
0.5f * (1.0f + std::cos(kStereoLeftRadians - source_direction.azimuth()) *
cos_direction_elevation);
(*stereo_gains)[1] =
0.5f *
(1.0f + std::cos(kStereoRightRadians - source_direction.azimuth()) *
cos_direction_elevation);
}
} // namespace vraudio