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/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/common_audio/signal_processing/include/real_fft.h"
#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
#include "webrtc/typedefs.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace webrtc {
namespace {
// FFT order.
const int kOrder = 5;
// Lengths for real FFT's time and frequency bufffers.
// For N-point FFT, the length requirements from API are N and N+2 respectively.
const int kTimeDataLength = 1 << kOrder;
const int kFreqDataLength = (1 << kOrder) + 2;
// For complex FFT's time and freq buffer. The implementation requires
// 2*N 16-bit words.
const int kComplexFftDataLength = 2 << kOrder;
// Reference data for time signal.
const int16_t kRefData[kTimeDataLength] = {
11739, 6848, -8688, 31980, -30295, 25242, 27085, 19410,
-26299, 15607, -10791, 11778, -23819, 14498, -25772, 10076,
1173, 6848, -8688, 31980, -30295, 2522, 27085, 19410,
-2629, 5607, -3, 1178, -23819, 1498, -25772, 10076
};
class RealFFTTest : public ::testing::Test {
protected:
RealFFTTest() {
WebRtcSpl_Init();
}
};
TEST_F(RealFFTTest, CreateFailsOnBadInput) {
RealFFT* fft = WebRtcSpl_CreateRealFFT(11);
EXPECT_TRUE(fft == NULL);
fft = WebRtcSpl_CreateRealFFT(-1);
EXPECT_TRUE(fft == NULL);
}
TEST_F(RealFFTTest, RealAndComplexMatch) {
int i = 0;
int j = 0;
int16_t real_fft_time[kTimeDataLength] = {0};
int16_t real_fft_freq[kFreqDataLength] = {0};
// One common buffer for complex FFT's time and frequency data.
int16_t complex_fft_buff[kComplexFftDataLength] = {0};
// Prepare the inputs to forward FFT's.
memcpy(real_fft_time, kRefData, sizeof(kRefData));
for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
complex_fft_buff[j] = kRefData[i];
complex_fft_buff[j + 1] = 0; // Insert zero's to imaginary parts.
};
// Create and run real forward FFT.
RealFFT* fft = WebRtcSpl_CreateRealFFT(kOrder);
EXPECT_TRUE(fft != NULL);
EXPECT_EQ(0, WebRtcSpl_RealForwardFFT(fft, real_fft_time, real_fft_freq));
// Run complex forward FFT.
WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
EXPECT_EQ(0, WebRtcSpl_ComplexFFT(complex_fft_buff, kOrder, 1));
// Verify the results between complex and real forward FFT.
for (i = 0; i < kFreqDataLength; i++) {
EXPECT_EQ(real_fft_freq[i], complex_fft_buff[i]);
}
// Prepare the inputs to inverse real FFT.
// We use whatever data in complex_fft_buff[] since we don't care
// about data contents. Only kFreqDataLength 16-bit words are copied
// from complex_fft_buff to real_fft_freq since remaining words (2nd half)
// are conjugate-symmetric to the first half in theory.
memcpy(real_fft_freq, complex_fft_buff, sizeof(real_fft_freq));
// Run real inverse FFT.
int real_scale = WebRtcSpl_RealInverseFFT(fft, real_fft_freq, real_fft_time);
EXPECT_GE(real_scale, 0);
// Run complex inverse FFT.
WebRtcSpl_ComplexBitReverse(complex_fft_buff, kOrder);
int complex_scale = WebRtcSpl_ComplexIFFT(complex_fft_buff, kOrder, 1);
// Verify the results between complex and real inverse FFT.
// They are not bit-exact, since complex IFFT doesn't produce
// exactly conjugate-symmetric data (between first and second half).
EXPECT_EQ(real_scale, complex_scale);
for (i = 0, j = 0; i < kTimeDataLength; i += 1, j += 2) {
EXPECT_LE(abs(real_fft_time[i] - complex_fft_buff[j]), 1);
}
WebRtcSpl_FreeRealFFT(fft);
}
} // namespace
} // namespace webrtc
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