Line data    Source code

       1             : /*
       2             :  * Copyright © 2014 Mozilla Foundation
       3             :  *
       4             :  * This program is made available under an ISC-style license.  See the
       5             :  * accompanying file LICENSE for details.
       6             :  */
       7             : 
       8             : #define _USE_MATH_DEFINES
       9             : #include <math.h>
      10             : #include <stdint.h>
      11             : 
      12             : #include "cubeb_panner.h"
      13             : 
      14             : #ifndef M_PI
      15             : #define M_PI 3.14159263
      16             : #endif
      17             : 
      18             : /**
      19             :  * We use a cos/sin law.
      20             :  */
      21             : 
      22             : namespace {
      23             : template<typename T>
      24           0 : void cubeb_pan_stereo_buffer(T * buf, uint32_t frames, float pan)
      25             : {
      26           0 :   if (pan == 0.0) {
      27           0 :     return;
      28             :   }
      29             :   /* rescale in [0; 1] */
      30           0 :   pan += 1;
      31           0 :   pan /= 2;
      32           0 :   float left_gain  = float(cos(pan * M_PI * 0.5));
      33           0 :   float right_gain = float(sin(pan * M_PI * 0.5));
      34             : 
      35             :   /* In we are panning on the left, pan the right channel into the left one and
      36             :    * vice-versa. */
      37           0 :   if (pan < 0.5) {
      38           0 :     for (uint32_t i = 0; i < frames * 2; i+=2) {
      39           0 :       buf[i]     = T(buf[i] + buf[i + 1] * left_gain);
      40           0 :       buf[i + 1] = T(buf[i + 1] * right_gain);
      41             :     }
      42             :   } else {
      43           0 :     for (uint32_t i = 0; i < frames * 2; i+=2) {
      44           0 :       buf[i]     = T(buf[i] * left_gain);
      45           0 :       buf[i + 1] = T(buf[i + 1] + buf[i] * right_gain);
      46             :     }
      47             :   }
      48             : }
      49             : }
      50             : 
      51           0 : void cubeb_pan_stereo_buffer_float(float * buf, uint32_t frames, float pan)
      52             : {
      53           0 :   cubeb_pan_stereo_buffer(buf, frames, pan);
      54           0 : }
      55             : 
      56           0 : void cubeb_pan_stereo_buffer_int(short * buf, uint32_t frames, float pan)
      57             : {
      58           0 :   cubeb_pan_stereo_buffer(buf, frames, pan);
      59           0 : }
      60             :