media/base/sinc_resampler.h - chromium/src - Git at Google

 // 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/macros.h"
 #include "base/memory/aligned_memory.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:
   enum {
     // 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+.
     kKernelSize = 32,

     // Default request size.  Affects how often and for how much SincResampler
     // calls back for input.  Must be greater than kKernelSize.
     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.
     kKernelOffsetCount = 32,
     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::Callback<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 kKernelSize.  Specify kDefaultRequestSize if there are no
   // request size constraints.
   SincResampler(double io_sample_rate_ratio,
                 int request_frames,
                 const ReadCB& read_cb);
   ~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_; }

   // 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);
 #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

   // 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_;

   // Pointers to the various regions inside |input_buffer_|.  See the diagram at
   // the top of the .cc file for more information.
   float* r0_;
   float* const r1_;
   float* const r2_;
   float* r3_;
   float* r4_;

   DISALLOW_COPY_AND_ASSIGN(SincResampler);
 };

 }  // namespace media

 #endif  // MEDIA_BASE_SINC_RESAMPLER_H_
	// 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/macros.h"
	#include "base/memory/aligned_memory.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:
	enum {
	// 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+.
	kKernelSize = 32,

	// Default request size. Affects how often and for how much SincResampler
	// calls back for input. Must be greater than kKernelSize.
	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.
	kKernelOffsetCount = 32,
	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::Callback<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 kKernelSize. Specify kDefaultRequestSize if there are no
	// request size constraints.
	SincResampler(double io_sample_rate_ratio,
	int request_frames,
	const ReadCB& read_cb);
	~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_; }

	// 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);
	#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

	// 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_;

	// Pointers to the various regions inside \|input_buffer_\|. See the diagram at
	// the top of the .cc file for more information.
	float* r0_;
	float* const r1_;
	float* const r2_;
	float* r3_;
	float* r4_;

	DISALLOW_COPY_AND_ASSIGN(SincResampler);
	};

	} // namespace media

	#endif // MEDIA_BASE_SINC_RESAMPLER_H_