real_fft_unittest.cc (3809B)
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 "common_audio/signal_processing/include/real_fft.h" 12 13 #include <cstdint> 14 #include <cstdlib> 15 #include <cstring> 16 17 #include "common_audio/signal_processing/include/signal_processing_library.h" 18 #include "test/gtest.h" 19 20 namespace webrtc { 21 namespace { 22 23 // FFT order. 24 constexpr int kOrder = 5; 25 // Lengths for real FFT's time and frequency bufffers. 26 // For N-point FFT, the length requirements from API are N and N+2 respectively. 27 constexpr int kTimeDataLength = 1 << kOrder; 28 constexpr int kFreqDataLength = (1 << kOrder) + 2; 29 // For complex FFT's time and freq buffer. The implementation requires 30 // 2*N 16-bit words. 31 constexpr int kComplexFftDataLength = 2 << kOrder; 32 // Reference data for time signal. 33 constexpr int16_t kRefData[kTimeDataLength] = { 34 11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410, 35 -26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076, 36 1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410, 37 -2629, 5607, -3, 1178, -23819, 1498, -25772, 10076}; 38 39 TEST(RealFFTTest, CreateFailsOnBadInput) { 40 RealFFT* fft = WebRtcSpl_CreateRealFFT(11); 41 EXPECT_TRUE(fft == nullptr); 42 fft = WebRtcSpl_CreateRealFFT(-1); 43 EXPECT_TRUE(fft == nullptr); 44 } 45 46 TEST(RealFFTTest, RealAndComplexMatch) { 47 int i = 0; 48 int j = 0; 49 int16_t real_fft_time[kTimeDataLength] = {0}; 50 int16_t real_fft_freq[kFreqDataLength] = {0}; 51 // One common buffer for complex FFT's time and frequency data. 52 int16_t complex_fft_buff[kComplexFftDataLength] = {0}; 53 54 // Prepare the inputs to forward FFT's. 55 memcpy(real_fft_time, kRefData, sizeof(kRefData)); 56 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 57 complex_fft_buff[j] = kRefData[i]; 58 complex_fft_buff[j + 1] = 0; // Insert zero's to imaginary parts. 59 } 60 61 // Create and run real forward FFT. 62 RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder); 63 EXPECT_TRUE(fft != nullptr); 64 EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq)); 65 66 // Run complex forward FFT. 67 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 68 EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1)); 69 70 // Verify the results between complex and real forward FFT. 71 for (i = 0; i < kFreqDataLength; i++) { 72 EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]); 73 } 74 75 // Prepare the inputs to inverse real FFT. 76 // We use whatever data in complex_fft_buff[] since we don't care 77 // about data contents. Only kFreqDataLength 16-bit words are copied 78 // from complex_fft_buff to real_fft_freq since remaining words (2nd half) 79 // are conjugate-symmetric to the first half in theory. 80 memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq)); 81 82 // Run real inverse FFT. 83 int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time); 84 EXPECT_GE(real_scale, 0); 85 86 // Run complex inverse FFT. 87 WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder); 88 int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1); 89 90 // Verify the results between complex and real inverse FFT. 91 // They are not bit-exact, since complex IFFT doesn't produce 92 // exactly conjugate-symmetric data (between first and second half). 93 EXPECT_EQ(real_scale, complex_scale); 94 for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) { 95 EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1); 96 } 97 98 WebRtcSpl_FreeRealFFT(fft); 99 } 100 101 } // namespace 102 } // namespace webrtc