61 lines
1.3 KiB
C++
61 lines
1.3 KiB
C++
/*
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* Copyright © 2014 Mozilla Foundation
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*
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* This program is made available under an ISC-style license. See the
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* accompanying file LICENSE for details.
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*/
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#define _USE_MATH_DEFINES
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#include <math.h>
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#include <stdint.h>
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#include "cubeb_panner.h"
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#ifndef M_PI
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#define M_PI 3.14159263
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#endif
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/**
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* We use a cos/sin law.
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*/
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namespace {
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template<typename T>
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void cubeb_pan_stereo_buffer(T * buf, uint32_t frames, float pan)
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{
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if (pan == 0.0) {
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return;
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}
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/* rescale in [0; 1] */
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pan += 1;
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pan /= 2;
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float left_gain = float(cos(pan * M_PI * 0.5));
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float right_gain = float(sin(pan * M_PI * 0.5));
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/* In we are panning on the left, pan the right channel into the left one and
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* vice-versa. */
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if (pan < 0.5) {
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for (uint32_t i = 0; i < frames * 2; i+=2) {
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buf[i] = T(buf[i] + buf[i + 1] * left_gain);
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buf[i + 1] = T(buf[i + 1] * right_gain);
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}
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} else {
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for (uint32_t i = 0; i < frames * 2; i+=2) {
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buf[i] = T(buf[i] * left_gain);
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buf[i + 1] = T(buf[i + 1] + buf[i] * right_gain);
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}
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}
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}
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}
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void cubeb_pan_stereo_buffer_float(float * buf, uint32_t frames, float pan)
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{
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cubeb_pan_stereo_buffer(buf, frames, pan);
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}
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void cubeb_pan_stereo_buffer_int(short * buf, uint32_t frames, float pan)
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{
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cubeb_pan_stereo_buffer(buf, frames, pan);
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}
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