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| 1 /* | |
| 2 * Copyright (c) 2014 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 WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_LAPPED_TRANSFORM_H_ | |
| 12 #define WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_LAPPED_TRANSFORM_H_ | |
| 13 | |
| 14 #include <complex> | |
| 15 #include <memory> | |
| 16 | |
| 17 #include "webrtc/common_audio/real_fourier.h" | |
| 18 #include "webrtc/modules/audio_processing/utility/blocker.h" | |
| 19 #include "webrtc/system_wrappers/include/aligned_array.h" | |
| 20 | |
| 21 namespace webrtc { | |
| 22 | |
| 23 // Helper class for audio processing modules which operate on frequency domain | |
| 24 // input derived from the windowed time domain audio stream. | |
| 25 // | |
| 26 // The input audio chunk is sliced into possibly overlapping blocks, multiplied | |
| 27 // by a window and transformed with an FFT implementation. The transformed data | |
| 28 // is supplied to the given callback for processing. The processed output is | |
| 29 // then inverse transformed into the time domain and spliced back into a chunk | |
| 30 // which constitutes the final output of this processing module. | |
| 31 class LappedTransform { | |
| 32 public: | |
| 33 class Callback { | |
| 34 public: | |
| 35 virtual ~Callback() {} | |
| 36 | |
| 37 virtual void ProcessAudioBlock(const std::complex<float>* const* in_block, | |
| 38 size_t num_in_channels, size_t frames, | |
| 39 size_t num_out_channels, | |
| 40 std::complex<float>* const* out_block) = 0; | |
| 41 }; | |
| 42 | |
| 43 // Construct a transform instance. |chunk_length| is the number of samples in | |
| 44 // each channel. |window| defines the window, owned by the caller (a copy is | |
| 45 // made internally); |window| should have length equal to |block_length|. | |
| 46 // |block_length| defines the length of a block, in samples. | |
| 47 // |shift_amount| is in samples. |callback| is the caller-owned audio | |
| 48 // processing function called for each block of the input chunk. | |
| 49 LappedTransform(size_t num_in_channels, | |
| 50 size_t num_out_channels, | |
| 51 size_t chunk_length, | |
| 52 const float* window, | |
| 53 size_t block_length, | |
| 54 size_t shift_amount, | |
| 55 Callback* callback); | |
| 56 ~LappedTransform() {} | |
| 57 | |
| 58 // Main audio processing helper method. Internally slices |in_chunk| into | |
| 59 // blocks, transforms them to frequency domain, calls the callback for each | |
| 60 // block and returns a de-blocked time domain chunk of audio through | |
| 61 // |out_chunk|. Both buffers are caller-owned. | |
| 62 void ProcessChunk(const float* const* in_chunk, float* const* out_chunk); | |
| 63 | |
| 64 // Get the chunk length. | |
| 65 // | |
| 66 // The chunk length is the number of samples per channel that must be passed | |
| 67 // to ProcessChunk via the parameter in_chunk. | |
| 68 // | |
| 69 // Returns the same chunk_length passed to the LappedTransform constructor. | |
| 70 size_t chunk_length() const { return chunk_length_; } | |
| 71 | |
| 72 // Get the number of input channels. | |
| 73 // | |
| 74 // This is the number of arrays that must be passed to ProcessChunk via | |
| 75 // in_chunk. | |
| 76 // | |
| 77 // Returns the same num_in_channels passed to the LappedTransform constructor. | |
| 78 size_t num_in_channels() const { return num_in_channels_; } | |
| 79 | |
| 80 // Get the number of output channels. | |
| 81 // | |
| 82 // This is the number of arrays that must be passed to ProcessChunk via | |
| 83 // out_chunk. | |
| 84 // | |
| 85 // Returns the same num_out_channels passed to the LappedTransform | |
| 86 // constructor. | |
| 87 size_t num_out_channels() const { return num_out_channels_; } | |
| 88 | |
| 89 private: | |
| 90 // Internal middleware callback, given to the blocker. Transforms each block | |
| 91 // and hands it over to the processing method given at construction time. | |
| 92 class BlockThunk : public BlockerCallback { | |
| 93 public: | |
| 94 explicit BlockThunk(LappedTransform* parent) : parent_(parent) {} | |
| 95 | |
| 96 virtual void ProcessBlock(const float* const* input, | |
| 97 size_t num_frames, | |
| 98 size_t num_input_channels, | |
| 99 size_t num_output_channels, | |
| 100 float* const* output); | |
| 101 | |
| 102 private: | |
| 103 LappedTransform* const parent_; | |
| 104 } blocker_callback_; | |
| 105 | |
| 106 const size_t num_in_channels_; | |
| 107 const size_t num_out_channels_; | |
| 108 | |
| 109 const size_t block_length_; | |
| 110 const size_t chunk_length_; | |
| 111 | |
| 112 Callback* const block_processor_; | |
| 113 Blocker blocker_; | |
| 114 | |
| 115 std::unique_ptr<RealFourier> fft_; | |
| 116 const size_t cplx_length_; | |
| 117 AlignedArray<float> real_buf_; | |
| 118 AlignedArray<std::complex<float> > cplx_pre_; | |
| 119 AlignedArray<std::complex<float> > cplx_post_; | |
| 120 }; | |
| 121 | |
| 122 } // namespace webrtc | |
| 123 | |
| 124 #endif // WEBRTC_MODULES_AUDIO_PROCESSING_UTILITY_LAPPED_TRANSFORM_H_ | |
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