76 lines
2.8 KiB
C
76 lines
2.8 KiB
C
|
/*
|
||
|
|
* Copyright (c) 2014 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.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#ifndef COMMON_AUDIO_REAL_FOURIER_H_
|
||
|
|
#define COMMON_AUDIO_REAL_FOURIER_H_
|
||
|
|
|
||
|
|
#include <stddef.h>
|
||
|
|
#include <complex>
|
||
|
|
#include <memory>
|
||
|
|
|
||
|
|
#include "rtc_base/memory/aligned_malloc.h"
|
||
|
|
|
||
|
|
// Uniform interface class for the real DFT and its inverse, for power-of-2
|
||
|
|
// input lengths. Also contains helper functions for buffer allocation, taking
|
||
|
|
// care of any memory alignment requirements the underlying library might have.
|
||
|
|
|
||
|
|
namespace webrtc {
|
||
|
|
|
||
|
|
class RealFourier {
|
||
|
|
public:
|
||
|
|
// Shorthand typenames for the scopers used by the buffer allocation helpers.
|
||
|
|
typedef std::unique_ptr<float[], AlignedFreeDeleter> fft_real_scoper;
|
||
|
|
typedef std::unique_ptr<std::complex<float>[], AlignedFreeDeleter>
|
||
|
|
fft_cplx_scoper;
|
||
|
|
|
||
|
|
// The alignment required for all input and output buffers, in bytes.
|
||
|
|
static const size_t kFftBufferAlignment;
|
||
|
|
|
||
|
|
// Construct a wrapper instance for the given input order, which must be
|
||
|
|
// between 1 and kMaxFftOrder, inclusively.
|
||
|
|
static std::unique_ptr<RealFourier> Create(int fft_order);
|
||
|
|
virtual ~RealFourier() {}
|
||
|
|
|
||
|
|
// Helper to compute the smallest FFT order (a power of 2) which will contain
|
||
|
|
// the given input length.
|
||
|
|
static int FftOrder(size_t length);
|
||
|
|
|
||
|
|
// Helper to compute the input length from the FFT order.
|
||
|
|
static size_t FftLength(int order);
|
||
|
|
|
||
|
|
// Helper to compute the exact length, in complex floats, of the transform
|
||
|
|
// output (i.e. |2^order / 2 + 1|).
|
||
|
|
static size_t ComplexLength(int order);
|
||
|
|
|
||
|
|
// Buffer allocation helpers. The buffers are large enough to hold |count|
|
||
|
|
// floats/complexes and suitably aligned for use by the implementation.
|
||
|
|
// The returned scopers are set up with proper deleters; the caller owns
|
||
|
|
// the allocated memory.
|
||
|
|
static fft_real_scoper AllocRealBuffer(int count);
|
||
|
|
static fft_cplx_scoper AllocCplxBuffer(int count);
|
||
|
|
|
||
|
|
// Main forward transform interface. The output array need only be big
|
||
|
|
// enough for |2^order / 2 + 1| elements - the conjugate pairs are not
|
||
|
|
// returned. Input and output must be properly aligned (e.g. through
|
||
|
|
// AllocRealBuffer and AllocCplxBuffer) and input length must be
|
||
|
|
// |2^order| (same as given at construction time).
|
||
|
|
virtual void Forward(const float* src, std::complex<float>* dest) const = 0;
|
||
|
|
|
||
|
|
// Inverse transform. Same input format as output above, conjugate pairs
|
||
|
|
// not needed.
|
||
|
|
virtual void Inverse(const std::complex<float>* src, float* dest) const = 0;
|
||
|
|
|
||
|
|
virtual int order() const = 0;
|
||
|
|
};
|
||
|
|
|
||
|
|
} // namespace webrtc
|
||
|
|
|
||
|
|
#endif // COMMON_AUDIO_REAL_FOURIER_H_
|