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- // Copyright (c) 2012 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #ifndef MEDIA_BASE_SINC_RESAMPLER_H_
- #define MEDIA_BASE_SINC_RESAMPLER_H_
- #include <memory>
- #include "base/callback.h"
- #include "base/gtest_prod_util.h"
- #include "base/memory/aligned_memory.h"
- #include "base/memory/raw_ptr.h"
- #include "build/build_config.h"
- #include "media/base/media_export.h"
- namespace media {
- // SincResampler is a high-quality single-channel sample-rate converter.
- class MEDIA_EXPORT SincResampler {
- public:
- // The kernel size can be adjusted for quality (higher is better) at the
- // expense of performance. Must be a multiple of 32.
- // TODO(dalecurtis): Test performance to see if we can jack this up to 64+.
- static constexpr int kKernelSize = 32;
- // Default request size. Affects how often and for how much SincResampler
- // calls back for input. Must be greater than kKernelSize.
- static constexpr int kDefaultRequestSize = 512;
- // The kernel offset count is used for interpolation and is the number of
- // sub-sample kernel shifts. Can be adjusted for quality (higher is better)
- // at the expense of allocating more memory.
- static constexpr int kKernelOffsetCount = 32;
- static constexpr int kKernelStorageSize =
- kKernelSize * (kKernelOffsetCount + 1);
- // Callback type for providing more data into the resampler. Expects |frames|
- // of data to be rendered into |destination|; zero padded if not enough frames
- // are available to satisfy the request.
- typedef base::RepeatingCallback<void(int frames, float* destination)> ReadCB;
- // Constructs a SincResampler with the specified |read_cb|, which is used to
- // acquire audio data for resampling. |io_sample_rate_ratio| is the ratio
- // of input / output sample rates. |request_frames| controls the size in
- // frames of the buffer requested by each |read_cb| call. The value must be
- // greater than 1.5*kKernelSize. Specify kDefaultRequestSize if there are no
- // request size constraints.
- SincResampler(double io_sample_rate_ratio,
- int request_frames,
- const ReadCB read_cb);
- SincResampler(const SincResampler&) = delete;
- SincResampler& operator=(const SincResampler&) = delete;
- ~SincResampler();
- // Resample |frames| of data from |read_cb_| into |destination|.
- void Resample(int frames, float* destination);
- // The maximum size in frames that guarantees Resample() will only make a
- // single call to |read_cb_| for more data. Note: If PrimeWithSilence() is
- // not called, chunk size will grow after the first two Resample() calls by
- // kKernelSize / (2 * io_sample_rate_ratio). See the .cc file for details.
- int ChunkSize() const { return chunk_size_; }
- // Returns the max number of frames that could be requested (via multiple
- // calls to |read_cb_|) during one Resample(|output_frames_requested|) call.
- int GetMaxInputFramesRequested(int output_frames_requested) const;
- // Guarantees that ChunkSize() will not change between calls by initializing
- // the input buffer with silence. Note, this will cause the first few samples
- // of output to be biased towards silence. Must be called again after Flush().
- void PrimeWithSilence();
- // Flush all buffered data and reset internal indices. Not thread safe, do
- // not call while Resample() is in progress. Note, if PrimeWithSilence() was
- // previously called it must be called again after the Flush().
- void Flush();
- // Update |io_sample_rate_ratio_|. SetRatio() will cause a reconstruction of
- // the kernels used for resampling. Not thread safe, do not call while
- // Resample() is in progress.
- void SetRatio(double io_sample_rate_ratio);
- float* get_kernel_for_testing() { return kernel_storage_.get(); }
- // Return number of input frames consumed by a callback but not yet processed.
- // Since input/output ratio can be fractional, so can this value.
- // Zero before first call to Resample().
- double BufferedFrames() const;
- private:
- FRIEND_TEST_ALL_PREFIXES(SincResamplerTest, Convolve);
- FRIEND_TEST_ALL_PREFIXES(SincResamplerPerfTest, Convolve_unoptimized_aligned);
- FRIEND_TEST_ALL_PREFIXES(SincResamplerPerfTest, Convolve_optimized_aligned);
- FRIEND_TEST_ALL_PREFIXES(SincResamplerPerfTest, Convolve_optimized_unaligned);
- void InitializeKernel();
- void UpdateRegions(bool second_load);
- // Compute convolution of |k1| and |k2| over |input_ptr|, resultant sums are
- // linearly interpolated using |kernel_interpolation_factor|. On x86, the
- // underlying implementation is chosen at run time based on SSE support. On
- // ARM, NEON support is chosen at compile time based on compilation flags.
- static float Convolve_C(const float* input_ptr, const float* k1,
- const float* k2, double kernel_interpolation_factor);
- #if defined(ARCH_CPU_X86_FAMILY)
- static float Convolve_SSE(const float* input_ptr, const float* k1,
- const float* k2,
- double kernel_interpolation_factor);
- static float Convolve_AVX2(const float* input_ptr,
- const float* k1,
- const float* k2,
- double kernel_interpolation_factor);
- #elif defined(ARCH_CPU_ARM_FAMILY) && defined(USE_NEON)
- static float Convolve_NEON(const float* input_ptr, const float* k1,
- const float* k2,
- double kernel_interpolation_factor);
- #endif
- // Selects runtime specific CPU features like SSE. Must be called before
- // using SincResampler.
- void InitializeCPUSpecificFeatures();
- // The ratio of input / output sample rates.
- double io_sample_rate_ratio_;
- // An index on the source input buffer with sub-sample precision. It must be
- // double precision to avoid drift.
- double virtual_source_idx_;
- // The buffer is primed once at the very beginning of processing.
- bool buffer_primed_;
- // Source of data for resampling.
- const ReadCB read_cb_;
- // The size (in samples) to request from each |read_cb_| execution.
- const int request_frames_;
- // The number of source frames processed per pass.
- int block_size_;
- // Cached value used for ChunkSize(). The maximum size in frames that
- // guarantees Resample() will only ask for input at most once.
- int chunk_size_;
- // The size (in samples) of the internal buffer used by the resampler.
- const int input_buffer_size_;
- // Contains kKernelOffsetCount kernels back-to-back, each of size kKernelSize.
- // The kernel offsets are sub-sample shifts of a windowed sinc shifted from
- // 0.0 to 1.0 sample.
- std::unique_ptr<float[], base::AlignedFreeDeleter> kernel_storage_;
- std::unique_ptr<float[], base::AlignedFreeDeleter> kernel_pre_sinc_storage_;
- std::unique_ptr<float[], base::AlignedFreeDeleter> kernel_window_storage_;
- // Data from the source is copied into this buffer for each processing pass.
- std::unique_ptr<float[], base::AlignedFreeDeleter> input_buffer_;
- // Stores the runtime selection of which Convolve function to use.
- using ConvolveProc = float (*)(const float*,
- const float*,
- const float*,
- double);
- ConvolveProc convolve_proc_;
- // Pointers to the various regions inside |input_buffer_|. See the diagram at
- // the top of the .cc file for more information.
- raw_ptr<float> r0_;
- const raw_ptr<float> r1_;
- const raw_ptr<float> r2_;
- raw_ptr<float> r3_;
- raw_ptr<float> r4_;
- };
- } // namespace media
- #endif // MEDIA_BASE_SINC_RESAMPLER_H_
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