325cff01b4
Add code for doing block-based frequency domain processing. Developed and reviewed in isolation. Corresponding export CL: https://chromereviews.googleplex.com/95187013/ R=bercic@google.com, kjellander@webrtc.org, turaj@webrtc.org Review URL: https://webrtc-codereview.appspot.com/31539004 git-svn-id: http://webrtc.googlecode.com/svn/trunk@7359 4adac7df-926f-26a2-2b94-8c16560cd09d
86 lines
3.1 KiB
C++
86 lines
3.1 KiB
C++
/*
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* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef WEBRTC_COMMON_AUDIO_REAL_FOURIER_H_
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#define WEBRTC_COMMON_AUDIO_REAL_FOURIER_H_
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#include <complex>
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#include "webrtc/system_wrappers/interface/aligned_malloc.h"
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#include "webrtc/system_wrappers/interface/scoped_ptr.h"
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// Uniform interface class for the real DFT and its inverse, for power-of-2
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// input lengths. Also contains helper functions for buffer allocation, taking
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// care of any memory alignment requirements the underlying library might have.
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namespace webrtc {
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class RealFourier {
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public:
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// Shorthand typenames for the scopers used by the buffer allocation helpers.
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typedef scoped_ptr<float[], AlignedFreeDeleter> fft_real_scoper;
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typedef scoped_ptr<std::complex<float>[], AlignedFreeDeleter> fft_cplx_scoper;
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// The maximum input order supported by this implementation.
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static const int kMaxFftOrder;
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// The alignment required for all input and output buffers, in bytes.
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static const int kFftBufferAlignment;
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// Construct a wrapper instance for the given input order, which must be
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// between 1 and kMaxFftOrder, inclusively.
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explicit RealFourier(int fft_order);
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~RealFourier();
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// Short helper to compute the smallest FFT order (a power of 2) which will
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// contain the given input length. Returns -1 if the order would have been
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// too big for the implementation.
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static int FftOrder(int length);
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// Short helper to compute the exact length, in complex floats, of the
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// transform output (i.e. |2^order / 2 + 1|).
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static int ComplexLength(int order);
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// Buffer allocation helpers. The buffers are large enough to hold |count|
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// floats/complexes and suitably aligned for use by the implementation.
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// The returned scopers are set up with proper deleters; the caller owns
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// the allocated memory.
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static fft_real_scoper AllocRealBuffer(int count);
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static fft_cplx_scoper AllocCplxBuffer(int count);
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// Main forward transform interface. The output array need only be big
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// enough for |2^order / 2 + 1| elements - the conjugate pairs are not
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// returned. Input and output must be properly aligned (e.g. through
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// AllocRealBuffer and AllocCplxBuffer) and input length must be
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// |2^order| (same as given at construction time).
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void Forward(const float* src, std::complex<float>* dest) const;
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// Inverse transform. Same input format as output above, conjugate pairs
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// not needed.
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void Inverse(const std::complex<float>* src, float* dest) const;
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int order() const {
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return order_;
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}
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private:
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// Basically a forward declare of OMXFFTSpec_R_F32. To get rid of the
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// dependency on openmax.
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typedef void OMXFFTSpec_R_F32_;
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const int order_;
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OMXFFTSpec_R_F32_* omx_spec_;
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};
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} // namespace webrtc
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#endif // WEBRTC_COMMON_AUDIO_REAL_FOURIER_H_
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