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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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