1/* 2 * Copyright (c) 2012 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 "webrtc/common_audio/signal_processing/include/real_fft.h" 12#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 13#include "webrtc/typedefs.h" 14 15#include "testing/gtest/include/gtest/gtest.h" 16 17namespace webrtc { 18namespace { 19 20// FFT order. 21const int kOrder = 5; 22// Lengths for real FFT's time and frequency bufffers. 23// For N-point FFT, the length requirements from API are N and N+2 respectively. 24const int kTimeDataLength = 1 << kOrder; 25const int kFreqDataLength = (1 << kOrder) + 2; 26// For complex FFT's time and freq buffer. The implementation requires 27// 2*N 16-bit words. 28const int kComplexFftDataLength = 2 << kOrder; 29// Reference data for time signal. 30const int16_t kRefData[kTimeDataLength] = { 31 11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410, 32 -26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076, 33 1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410, 34 -2629, 5607, -3, 1178, -23819, 1498, -25772, 10076 35}; 36 37class RealFFTTest : public ::testing::Test { 38 protected: 39 RealFFTTest() { 40 WebRtcSpl_Init(); 41 } 42}; 43 44TEST_F(RealFFTTest, CreateFailsOnBadInput) { 45 RealFFT* fft = WebRtcSpl_CreateRealFFT(11); 46 EXPECT_TRUE(fft == NULL); 47 fft = WebRtcSpl_CreateRealFFT(-1); 48 EXPECT_TRUE(fft == NULL); 49} 50 51TEST_F(RealFFTTest, RealAndComplexMatch) { 52 int i = 0; 53 int j = 0; 54 int16_t real_fft_time[kTimeDataLength] = {0}; 55 int16_t real_fft_freq[kFreqDataLength] = {0}; 56 // One common buffer for complex FFT's time and frequency data. 57 int16_t complex_fft_buff[kComplexFftDataLength] = {0}; 58 59 // Prepare the inputs to forward FFT's. 60 memcpy(real_fft_time, kRefData, sizeof(kRefData)); 61 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 62 complex_fft_buff[j] = kRefData[i]; 63 complex_fft_buff[j + 1] = 0; // Insert zero's to imaginary parts. 64 }; 65 66 // Create and run real forward FFT. 67 RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder); 68 EXPECT_TRUE(fft != NULL); 69 EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq)); 70 71 // Run complex forward FFT. 72 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 73 EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1)); 74 75 // Verify the results between complex and real forward FFT. 76 for (i = 0; i < kFreqDataLength; i++) { 77 EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]); 78 } 79 80 // Prepare the inputs to inverse real FFT. 81 // We use whatever data in complex_fft_buff[] since we don't care 82 // about data contents. Only kFreqDataLength 16-bit words are copied 83 // from complex_fft_buff to real_fft_freq since remaining words (2nd half) 84 // are conjugate-symmetric to the first half in theory. 85 memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq)); 86 87 // Run real inverse FFT. 88 int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time); 89 EXPECT_GE(real_scale, 0); 90 91 // Run complex inverse FFT. 92 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 93 int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1); 94 95 // Verify the results between complex and real inverse FFT. 96 // They are not bit-exact, since complex IFFT doesn't produce 97 // exactly conjugate-symmetric data (between first and second half). 98 EXPECT_EQ(real_scale, complex_scale); 99 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 100 EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1); 101 } 102 103 WebRtcSpl_FreeRealFFT(fft); 104} 105 106} // namespace 107} // namespace webrtc 108