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/test/testsupport/gtest_disable.h"
14#include "webrtc/typedefs.h"
15
16#include "testing/gtest/include/gtest/gtest.h"
17
18namespace webrtc {
19namespace {
20
21// FFT order.
22const int kOrder = 5;
23// Lengths for real FFT's time and frequency bufffers.
24// For N-point FFT, the length requirements from API are N and N+2 respectively.
25const int kTimeDataLength = 1 << kOrder;
26const int kFreqDataLength = (1 << kOrder) + 2;
27// For complex FFT's time and freq buffer. The implementation requires
28// 2*N 16-bit words.
29const int kComplexFftDataLength = 2 << kOrder;
30// Reference data for time signal.
31const int16_t kRefData[kTimeDataLength] = {
32  11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410,
33  -26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076,
34  1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410,
35  -2629, 5607, -3, 1178, -23819, 1498, -25772, 10076
36};
37
38class RealFFTTest : public ::testing::Test {
39 protected:
40   RealFFTTest() {
41     WebRtcSpl_Init();
42   }
43};
44
45TEST_F(RealFFTTest, CreateFailsOnBadInput) {
46  RealFFT* fft = WebRtcSpl_CreateRealFFT(11);
47  EXPECT_TRUE(fft == NULL);
48  fft = WebRtcSpl_CreateRealFFT(-1);
49  EXPECT_TRUE(fft == NULL);
50}
51
52TEST_F(RealFFTTest, RealAndComplexMatch) {
53  int i = 0;
54  int j = 0;
55  int16_t real_fft_time[kTimeDataLength] = {0};
56  int16_t real_fft_freq[kFreqDataLength] = {0};
57  // One common buffer for complex FFT's time and frequency data.
58  int16_t complex_fft_buff[kComplexFftDataLength] = {0};
59
60  // Prepare the inputs to forward FFT's.
61  memcpy(real_fft_time, kRefData, sizeof(kRefData));
62  for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
63    complex_fft_buff[j] = kRefData[i];
64    complex_fft_buff[j + 1] = 0;  // Insert zero's to imaginary parts.
65  };
66
67  // Create and run real forward FFT.
68  RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder);
69  EXPECT_TRUE(fft != NULL);
70  EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq));
71
72  // Run complex forward FFT.
73  WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
74  EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1));
75
76  // Verify the results between complex and real forward FFT.
77  for (i = 0; i < kFreqDataLength; i++) {
78    EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]);
79  }
80
81  // Prepare the inputs to inverse real FFT.
82  // We use whatever data in complex_fft_buff[] since we don't care
83  // about data contents. Only kFreqDataLength 16-bit words are copied
84  // from complex_fft_buff to real_fft_freq since remaining words (2nd half)
85  // are conjugate-symmetric to the first half in theory.
86  memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq));
87
88  // Run real inverse FFT.
89  int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time);
90  EXPECT_GE(real_scale, 0);
91
92  // Run complex inverse FFT.
93  WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
94  int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1);
95
96  // Verify the results between complex and real inverse FFT.
97  // They are not bit-exact, since complex IFFT doesn't produce
98  // exactly conjugate-symmetric data (between first and second half).
99  EXPECT_EQ(real_scale, complex_scale);
100  for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
101    EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1);
102  }
103
104  WebRtcSpl_FreeRealFFT(fft);
105}
106
107}  // namespace
108}  // namespace webrtc
109