1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "settings.h" 12 #include "fft.h" 13 #include "codec.h" 14 #include "os_specific_inline.h" 15 #include <math.h> 16 17 static double costab1[FRAMESAMPLES_HALF]; 18 static double sintab1[FRAMESAMPLES_HALF]; 19 static double costab2[FRAMESAMPLES_QUARTER]; 20 static double sintab2[FRAMESAMPLES_QUARTER]; 21 22 void WebRtcIsac_InitTransform() 23 { 24 int k; 25 double fact, phase; 26 27 fact = PI / (FRAMESAMPLES_HALF); 28 phase = 0.0; 29 for (k = 0; k < FRAMESAMPLES_HALF; k++) { 30 costab1[k] = cos(phase); 31 sintab1[k] = sin(phase); 32 phase += fact; 33 } 34 35 fact = PI * ((double) (FRAMESAMPLES_HALF - 1)) / ((double) FRAMESAMPLES_HALF); 36 phase = 0.5 * fact; 37 for (k = 0; k < FRAMESAMPLES_QUARTER; k++) { 38 costab2[k] = cos(phase); 39 sintab2[k] = sin(phase); 40 phase += fact; 41 } 42 } 43 44 45 void WebRtcIsac_Time2Spec(double *inre1, 46 double *inre2, 47 int16_t *outreQ7, 48 int16_t *outimQ7, 49 FFTstr *fftstr_obj) 50 { 51 52 int k; 53 int dims[1]; 54 double tmp1r, tmp1i, xr, xi, yr, yi, fact; 55 double tmpre[FRAMESAMPLES_HALF], tmpim[FRAMESAMPLES_HALF]; 56 57 58 dims[0] = FRAMESAMPLES_HALF; 59 60 61 /* Multiply with complex exponentials and combine into one complex vector */ 62 fact = 0.5 / sqrt(FRAMESAMPLES_HALF); 63 for (k = 0; k < FRAMESAMPLES_HALF; k++) { 64 tmp1r = costab1[k]; 65 tmp1i = sintab1[k]; 66 tmpre[k] = (inre1[k] * tmp1r + inre2[k] * tmp1i) * fact; 67 tmpim[k] = (inre2[k] * tmp1r - inre1[k] * tmp1i) * fact; 68 } 69 70 71 /* Get DFT */ 72 WebRtcIsac_Fftns(1, dims, tmpre, tmpim, -1, 1.0, fftstr_obj); 73 74 /* Use symmetry to separate into two complex vectors and center frames in time around zero */ 75 for (k = 0; k < FRAMESAMPLES_QUARTER; k++) { 76 xr = tmpre[k] + tmpre[FRAMESAMPLES_HALF - 1 - k]; 77 yi = -tmpre[k] + tmpre[FRAMESAMPLES_HALF - 1 - k]; 78 xi = tmpim[k] - tmpim[FRAMESAMPLES_HALF - 1 - k]; 79 yr = tmpim[k] + tmpim[FRAMESAMPLES_HALF - 1 - k]; 80 81 tmp1r = costab2[k]; 82 tmp1i = sintab2[k]; 83 outreQ7[k] = (int16_t)WebRtcIsac_lrint((xr * tmp1r - xi * tmp1i) * 128.0); 84 outimQ7[k] = (int16_t)WebRtcIsac_lrint((xr * tmp1i + xi * tmp1r) * 128.0); 85 outreQ7[FRAMESAMPLES_HALF - 1 - k] = (int16_t)WebRtcIsac_lrint((-yr * tmp1i - yi * tmp1r) * 128.0); 86 outimQ7[FRAMESAMPLES_HALF - 1 - k] = (int16_t)WebRtcIsac_lrint((-yr * tmp1r + yi * tmp1i) * 128.0); 87 } 88 } 89 90 91 void WebRtcIsac_Spec2time(double *inre, double *inim, double *outre1, double *outre2, FFTstr *fftstr_obj) 92 { 93 94 int k; 95 double tmp1r, tmp1i, xr, xi, yr, yi, fact; 96 97 int dims; 98 99 dims = FRAMESAMPLES_HALF; 100 101 for (k = 0; k < FRAMESAMPLES_QUARTER; k++) { 102 /* Move zero in time to beginning of frames */ 103 tmp1r = costab2[k]; 104 tmp1i = sintab2[k]; 105 xr = inre[k] * tmp1r + inim[k] * tmp1i; 106 xi = inim[k] * tmp1r - inre[k] * tmp1i; 107 yr = -inim[FRAMESAMPLES_HALF - 1 - k] * tmp1r - inre[FRAMESAMPLES_HALF - 1 - k] * tmp1i; 108 yi = -inre[FRAMESAMPLES_HALF - 1 - k] * tmp1r + inim[FRAMESAMPLES_HALF - 1 - k] * tmp1i; 109 110 /* Combine into one vector, z = x + j * y */ 111 outre1[k] = xr - yi; 112 outre1[FRAMESAMPLES_HALF - 1 - k] = xr + yi; 113 outre2[k] = xi + yr; 114 outre2[FRAMESAMPLES_HALF - 1 - k] = -xi + yr; 115 } 116 117 118 /* Get IDFT */ 119 WebRtcIsac_Fftns(1, &dims, outre1, outre2, 1, FRAMESAMPLES_HALF, fftstr_obj); 120 121 122 /* Demodulate and separate */ 123 fact = sqrt(FRAMESAMPLES_HALF); 124 for (k = 0; k < FRAMESAMPLES_HALF; k++) { 125 tmp1r = costab1[k]; 126 tmp1i = sintab1[k]; 127 xr = (outre1[k] * tmp1r - outre2[k] * tmp1i) * fact; 128 outre2[k] = (outre2[k] * tmp1r + outre1[k] * tmp1i) * fact; 129 outre1[k] = xr; 130 } 131 } 132
