1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef MEDIA_BASE_SINC_RESAMPLER_H_ 6 #define MEDIA_BASE_SINC_RESAMPLER_H_ 7 8 #include "base/callback.h" 9 #include "base/gtest_prod_util.h" 10 #include "base/memory/aligned_memory.h" 11 #include "base/memory/scoped_ptr.h" 12 #include "build/build_config.h" 13 #include "media/base/media_export.h" 14 15 namespace media { 16 17 // SincResampler is a high-quality single-channel sample-rate converter. 18 class MEDIA_EXPORT SincResampler { 19 public: 20 enum { 21 // The kernel size can be adjusted for quality (higher is better) at the 22 // expense of performance. Must be a multiple of 32. 23 // TODO(dalecurtis): Test performance to see if we can jack this up to 64+. 24 kKernelSize = 32, 25 26 // Default request size. Affects how often and for how much SincResampler 27 // calls back for input. Must be greater than kKernelSize. 28 kDefaultRequestSize = 512, 29 30 // The kernel offset count is used for interpolation and is the number of 31 // sub-sample kernel shifts. Can be adjusted for quality (higher is better) 32 // at the expense of allocating more memory. 33 kKernelOffsetCount = 32, 34 kKernelStorageSize = kKernelSize * (kKernelOffsetCount + 1), 35 }; 36 37 // Callback type for providing more data into the resampler. Expects |frames| 38 // of data to be rendered into |destination|; zero padded if not enough frames 39 // are available to satisfy the request. 40 typedef base::Callback<void(int frames, float* destination)> ReadCB; 41 42 // Constructs a SincResampler with the specified |read_cb|, which is used to 43 // acquire audio data for resampling. |io_sample_rate_ratio| is the ratio 44 // of input / output sample rates. |request_frames| controls the size in 45 // frames of the buffer requested by each |read_cb| call. The value must be 46 // greater than kKernelSize. Specify kDefaultRequestSize if there are no 47 // request size constraints. 48 SincResampler(double io_sample_rate_ratio, 49 int request_frames, 50 const ReadCB& read_cb); 51 virtual ~SincResampler(); 52 53 // Resample |frames| of data from |read_cb_| into |destination|. 54 void Resample(int frames, float* destination); 55 56 // The maximum size in frames that guarantees Resample() will only make a 57 // single call to |read_cb_| for more data. 58 int ChunkSize() const; 59 60 // Flush all buffered data and reset internal indices. Not thread safe, do 61 // not call while Resample() is in progress. 62 void Flush(); 63 64 // Update |io_sample_rate_ratio_|. SetRatio() will cause a reconstruction of 65 // the kernels used for resampling. Not thread safe, do not call while 66 // Resample() is in progress. 67 void SetRatio(double io_sample_rate_ratio); 68 69 float* get_kernel_for_testing() { return kernel_storage_.get(); } 70 71 private: 72 FRIEND_TEST_ALL_PREFIXES(SincResamplerTest, Convolve); 73 FRIEND_TEST_ALL_PREFIXES(SincResamplerPerfTest, Convolve); 74 75 void InitializeKernel(); 76 void UpdateRegions(bool second_load); 77 78 // Compute convolution of |k1| and |k2| over |input_ptr|, resultant sums are 79 // linearly interpolated using |kernel_interpolation_factor|. On x86, the 80 // underlying implementation is chosen at run time based on SSE support. On 81 // ARM, NEON support is chosen at compile time based on compilation flags. 82 static float Convolve_C(const float* input_ptr, const float* k1, 83 const float* k2, double kernel_interpolation_factor); 84 #if defined(ARCH_CPU_X86_FAMILY) 85 static float Convolve_SSE(const float* input_ptr, const float* k1, 86 const float* k2, 87 double kernel_interpolation_factor); 88 #elif defined(ARCH_CPU_ARM_FAMILY) && defined(USE_NEON) 89 static float Convolve_NEON(const float* input_ptr, const float* k1, 90 const float* k2, 91 double kernel_interpolation_factor); 92 #endif 93 94 // The ratio of input / output sample rates. 95 double io_sample_rate_ratio_; 96 97 // An index on the source input buffer with sub-sample precision. It must be 98 // double precision to avoid drift. 99 double virtual_source_idx_; 100 101 // The buffer is primed once at the very beginning of processing. 102 bool buffer_primed_; 103 104 // Source of data for resampling. 105 const ReadCB read_cb_; 106 107 // The size (in samples) to request from each |read_cb_| execution. 108 const int request_frames_; 109 110 // The number of source frames processed per pass. 111 int block_size_; 112 113 // The size (in samples) of the internal buffer used by the resampler. 114 const int input_buffer_size_; 115 116 // Contains kKernelOffsetCount kernels back-to-back, each of size kKernelSize. 117 // The kernel offsets are sub-sample shifts of a windowed sinc shifted from 118 // 0.0 to 1.0 sample. 119 scoped_ptr<float[], base::AlignedFreeDeleter> kernel_storage_; 120 scoped_ptr<float[], base::AlignedFreeDeleter> kernel_pre_sinc_storage_; 121 scoped_ptr<float[], base::AlignedFreeDeleter> kernel_window_storage_; 122 123 // Data from the source is copied into this buffer for each processing pass. 124 scoped_ptr<float[], base::AlignedFreeDeleter> input_buffer_; 125 126 // Pointers to the various regions inside |input_buffer_|. See the diagram at 127 // the top of the .cc file for more information. 128 float* r0_; 129 float* const r1_; 130 float* const r2_; 131 float* r3_; 132 float* r4_; 133 134 DISALLOW_COPY_AND_ASSIGN(SincResampler); 135 }; 136 137 } // namespace media 138 139 #endif // MEDIA_BASE_SINC_RESAMPLER_H_ 140
