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pffft_wrapper.h (3203B)

      1 /*
      2 *  Copyright (c) 2019 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 #ifndef MODULES_AUDIO_PROCESSING_UTILITY_PFFFT_WRAPPER_H_
     12 #define MODULES_AUDIO_PROCESSING_UTILITY_PFFFT_WRAPPER_H_
     13 
     14 #include <cstddef>
     15 #include <memory>
     16 
     17 #include "api/array_view.h"
     18 
     19 // Forward declaration.
     20 struct PFFFT_Setup;
     21 
     22 namespace webrtc {
     23 
     24 // Pretty-Fast Fast Fourier Transform (PFFFT) wrapper class.
     25 // Not thread safe.
     26 class Pffft {
     27 public:
     28  enum class FftType { kReal, kComplex };
     29 
     30  // 1D floating point buffer used as input/output data type for the FFT ops.
     31  // It must be constructed using Pffft::CreateBuffer().
     32  class FloatBuffer {
     33   public:
     34    FloatBuffer(const FloatBuffer&) = delete;
     35    FloatBuffer& operator=(const FloatBuffer&) = delete;
     36    ~FloatBuffer();
     37 
     38    ArrayView<const float> GetConstView() const;
     39    ArrayView<float> GetView();
     40 
     41   private:
     42    friend class Pffft;
     43    FloatBuffer(size_t fft_size, FftType fft_type);
     44    const float* const_data() const { return data_; }
     45    float* data() { return data_; }
     46    size_t size() const { return size_; }
     47 
     48    const size_t size_;
     49    float* const data_;
     50  };
     51 
     52  // TODO(https://crbug.com/webrtc/9577): Consider adding a factory and making
     53  // the ctor private.
     54  // static std::unique_ptr<Pffft> Create(size_t fft_size,
     55  // FftType fft_type); Ctor. `fft_size` must be a supported size (see
     56  // Pffft::IsValidFftSize()). If not supported, the code will crash.
     57  Pffft(size_t fft_size, FftType fft_type);
     58  Pffft(const Pffft&) = delete;
     59  Pffft& operator=(const Pffft&) = delete;
     60  ~Pffft();
     61 
     62  // Returns true if the FFT size is supported.
     63  static bool IsValidFftSize(size_t fft_size, FftType fft_type);
     64 
     65  // Returns true if SIMD code optimizations are being used.
     66  static bool IsSimdEnabled();
     67 
     68  // Creates a buffer of the right size.
     69  std::unique_ptr<FloatBuffer> CreateBuffer() const;
     70 
     71  // TODO(https://crbug.com/webrtc/9577): Overload with ArrayView args.
     72  // Computes the forward fast Fourier transform.
     73  void ForwardTransform(const FloatBuffer& in, FloatBuffer* out, bool ordered);
     74  // Computes the backward fast Fourier transform.
     75  void BackwardTransform(const FloatBuffer& in, FloatBuffer* out, bool ordered);
     76 
     77  // Multiplies the frequency components of `fft_x` and `fft_y` and accumulates
     78  // them into `out`. The arrays must have been obtained with
     79  // ForwardTransform(..., /*ordered=*/false) - i.e., `fft_x` and `fft_y` must
     80  // not be ordered.
     81  void FrequencyDomainConvolve(const FloatBuffer& fft_x,
     82                               const FloatBuffer& fft_y,
     83                               FloatBuffer* out,
     84                               float scaling = 1.f);
     85 
     86 private:
     87  const size_t fft_size_;
     88  const FftType fft_type_;
     89  PFFFT_Setup* pffft_status_;
     90  float* const scratch_buffer_;
     91 };
     92 
     93 }  // namespace webrtc
     94 
     95 #endif  // MODULES_AUDIO_PROCESSING_UTILITY_PFFFT_WRAPPER_H_