common_audio/blocker.cc - src/webrtc - Git at Google

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "webrtc/common_audio/blocker.h"

 #include <string.h>

 #include "webrtc/rtc_base/checks.h"

 namespace {

 // Adds |a| and |b| frame by frame into |result| (basically matrix addition).
 void AddFrames(const float* const* a,
                size_t a_start_index,
                const float* const* b,
                int b_start_index,
                size_t num_frames,
                size_t num_channels,
                float* const* result,
                size_t result_start_index) {
   for (size_t i = 0; i < num_channels; ++i) {
     for (size_t j = 0; j < num_frames; ++j) {
       result[i][j + result_start_index] =
           a[i][j + a_start_index] + b[i][j + b_start_index];
     }
   }
 }

 // Copies |src| into |dst| channel by channel.
 void CopyFrames(const float* const* src,
                 size_t src_start_index,
                 size_t num_frames,
                 size_t num_channels,
                 float* const* dst,
                 size_t dst_start_index) {
   for (size_t i = 0; i < num_channels; ++i) {
     memcpy(&dst[i][dst_start_index],
            &src[i][src_start_index],
            num_frames * sizeof(dst[i][dst_start_index]));
   }
 }

 // Moves |src| into |dst| channel by channel.
 void MoveFrames(const float* const* src,
                 size_t src_start_index,
                 size_t num_frames,
                 size_t num_channels,
                 float* const* dst,
                 size_t dst_start_index) {
   for (size_t i = 0; i < num_channels; ++i) {
     memmove(&dst[i][dst_start_index],
             &src[i][src_start_index],
             num_frames * sizeof(dst[i][dst_start_index]));
   }
 }

 void ZeroOut(float* const* buffer,
              size_t starting_idx,
              size_t num_frames,
              size_t num_channels) {
   for (size_t i = 0; i < num_channels; ++i) {
     memset(&buffer[i][starting_idx], 0,
            num_frames * sizeof(buffer[i][starting_idx]));
   }
 }

 // Pointwise multiplies each channel of |frames| with |window|. Results are
 // stored in |frames|.
 void ApplyWindow(const float* window,
                  size_t num_frames,
                  size_t num_channels,
                  float* const* frames) {
   for (size_t i = 0; i < num_channels; ++i) {
     for (size_t j = 0; j < num_frames; ++j) {
       frames[i][j] = frames[i][j] * window[j];
     }
   }
 }

 size_t gcd(size_t a, size_t b) {
   size_t tmp;
   while (b) {
      tmp = a;
      a = b;
      b = tmp % b;
   }
   return a;
 }

 }  // namespace

 namespace webrtc {

 Blocker::Blocker(size_t chunk_size,
                  size_t block_size,
                  size_t num_input_channels,
                  size_t num_output_channels,
                  const float* window,
                  size_t shift_amount,
                  BlockerCallback* callback)
     : chunk_size_(chunk_size),
       block_size_(block_size),
       num_input_channels_(num_input_channels),
       num_output_channels_(num_output_channels),
       initial_delay_(block_size_ - gcd(chunk_size, shift_amount)),
       frame_offset_(0),
       input_buffer_(num_input_channels_, chunk_size_ + initial_delay_),
       output_buffer_(chunk_size_ + initial_delay_, num_output_channels_),
       input_block_(block_size_, num_input_channels_),
       output_block_(block_size_, num_output_channels_),
       window_(new float[block_size_]),
       shift_amount_(shift_amount),
       callback_(callback) {
   RTC_CHECK_LE(num_output_channels_, num_input_channels_);
   RTC_CHECK_LE(shift_amount_, block_size_);

   memcpy(window_.get(), window, block_size_ * sizeof(*window_.get()));
   input_buffer_.MoveReadPositionBackward(initial_delay_);
 }

 Blocker::~Blocker() = default;

 // When block_size < chunk_size the input and output buffers look like this:
 //
 //                      delay*             chunk_size    chunk_size + delay*
 //  buffer: <-------------|---------------------|---------------|>
 //                _a_              _b_                 _c_
 //
 // On each call to ProcessChunk():
 // 1. New input gets read into sections _b_ and _c_ of the input buffer.
 // 2. We block starting from frame_offset.
 // 3. We block until we reach a block |bl| that doesn't contain any frames
 //    from sections _a_ or _b_ of the input buffer.
 // 4. We window the current block, fire the callback for processing, window
 //    again, and overlap/add to the output buffer.
 // 5. We copy sections _a_ and _b_ of the output buffer into output.
 // 6. For both the input and the output buffers, we copy section _c_ into
 //    section _a_.
 // 7. We set the new frame_offset to be the difference between the first frame
 //    of |bl| and the border between sections _b_ and _c_.
 //
 // When block_size > chunk_size the input and output buffers look like this:
 //
 //                   chunk_size               delay*       chunk_size + delay*
 //  buffer: <-------------|---------------------|---------------|>
 //                _a_              _b_                 _c_
 //
 // On each call to ProcessChunk():
 // The procedure is the same as above, except for:
 // 1. New input gets read into section _c_ of the input buffer.
 // 3. We block until we reach a block |bl| that doesn't contain any frames
 //    from section _a_ of the input buffer.
 // 5. We copy section _a_ of the output buffer into output.
 // 6. For both the input and the output buffers, we copy sections _b_ and _c_
 //    into section _a_ and _b_.
 // 7. We set the new frame_offset to be the difference between the first frame
 //    of |bl| and the border between sections _a_ and _b_.
 //
 // * delay here refers to inintial_delay_
 //
 // TODO(claguna): Look at using ring buffers to eliminate some copies.
 void Blocker::ProcessChunk(const float* const* input,
                            size_t chunk_size,
                            size_t num_input_channels,
                            size_t num_output_channels,
                            float* const* output) {
   RTC_CHECK_EQ(chunk_size, chunk_size_);
   RTC_CHECK_EQ(num_input_channels, num_input_channels_);
   RTC_CHECK_EQ(num_output_channels, num_output_channels_);

   input_buffer_.Write(input, num_input_channels, chunk_size_);
   size_t first_frame_in_block = frame_offset_;

   // Loop through blocks.
   while (first_frame_in_block < chunk_size_) {
     input_buffer_.Read(input_block_.channels(), num_input_channels,
                        block_size_);
     input_buffer_.MoveReadPositionBackward(block_size_ - shift_amount_);

     ApplyWindow(window_.get(),
                 block_size_,
                 num_input_channels_,
                 input_block_.channels());
     callback_->ProcessBlock(input_block_.channels(),
                             block_size_,
                             num_input_channels_,
                             num_output_channels_,
                             output_block_.channels());
     ApplyWindow(window_.get(),
                 block_size_,
                 num_output_channels_,
                 output_block_.channels());

     AddFrames(output_buffer_.channels(),
               first_frame_in_block,
               output_block_.channels(),
               0,
               block_size_,
               num_output_channels_,
               output_buffer_.channels(),
               first_frame_in_block);

     first_frame_in_block += shift_amount_;
   }

   // Copy output buffer to output
   CopyFrames(output_buffer_.channels(),
              0,
              chunk_size_,
              num_output_channels_,
              output,
              0);

   // Copy output buffer [chunk_size_, chunk_size_ + initial_delay]
   // to output buffer [0, initial_delay], zero the rest.
   MoveFrames(output_buffer_.channels(),
              chunk_size,
              initial_delay_,
              num_output_channels_,
              output_buffer_.channels(),
              0);
   ZeroOut(output_buffer_.channels(),
           initial_delay_,
           chunk_size_,
           num_output_channels_);

   // Calculate new starting frames.
   frame_offset_ = first_frame_in_block - chunk_size_;
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "webrtc/common_audio/blocker.h"

	#include <string.h>

	#include "webrtc/rtc_base/checks.h"

	namespace {

	// Adds \|a\| and \|b\| frame by frame into \|result\| (basically matrix addition).
	void AddFrames(const float* const* a,
	size_t a_start_index,
	const float* const* b,
	int b_start_index,
	size_t num_frames,
	size_t num_channels,
	float* const* result,
	size_t result_start_index) {
	for (size_t i = 0; i < num_channels; ++i) {
	for (size_t j = 0; j < num_frames; ++j) {
	result[i][j + result_start_index] =
	a[i][j + a_start_index] + b[i][j + b_start_index];
	}
	}
	}

	// Copies \|src\| into \|dst\| channel by channel.
	void CopyFrames(const float* const* src,
	size_t src_start_index,
	size_t num_frames,
	size_t num_channels,
	float* const* dst,
	size_t dst_start_index) {
	for (size_t i = 0; i < num_channels; ++i) {
	memcpy(&dst[i][dst_start_index],
	&src[i][src_start_index],
	num_frames * sizeof(dst[i][dst_start_index]));
	}
	}

	// Moves \|src\| into \|dst\| channel by channel.
	void MoveFrames(const float* const* src,
	size_t src_start_index,
	size_t num_frames,
	size_t num_channels,
	float* const* dst,
	size_t dst_start_index) {
	for (size_t i = 0; i < num_channels; ++i) {
	memmove(&dst[i][dst_start_index],
	&src[i][src_start_index],
	num_frames * sizeof(dst[i][dst_start_index]));
	}
	}

	void ZeroOut(float* const* buffer,
	size_t starting_idx,
	size_t num_frames,
	size_t num_channels) {
	for (size_t i = 0; i < num_channels; ++i) {
	memset(&buffer[i][starting_idx], 0,
	num_frames * sizeof(buffer[i][starting_idx]));
	}
	}

	// Pointwise multiplies each channel of \|frames\| with \|window\|. Results are
	// stored in \|frames\|.
	void ApplyWindow(const float* window,
	size_t num_frames,
	size_t num_channels,
	float* const* frames) {
	for (size_t i = 0; i < num_channels; ++i) {
	for (size_t j = 0; j < num_frames; ++j) {
	frames[i][j] = frames[i][j] * window[j];
	}
	}
	}

	size_t gcd(size_t a, size_t b) {
	size_t tmp;
	while (b) {
	tmp = a;
	a = b;
	b = tmp % b;
	}
	return a;
	}

	} // namespace

	namespace webrtc {

	Blocker::Blocker(size_t chunk_size,
	size_t block_size,
	size_t num_input_channels,
	size_t num_output_channels,
	const float* window,
	size_t shift_amount,
	BlockerCallback* callback)
	: chunk_size_(chunk_size),
	block_size_(block_size),
	num_input_channels_(num_input_channels),
	num_output_channels_(num_output_channels),
	initial_delay_(block_size_ - gcd(chunk_size, shift_amount)),
	frame_offset_(0),
	input_buffer_(num_input_channels_, chunk_size_ + initial_delay_),
	output_buffer_(chunk_size_ + initial_delay_, num_output_channels_),
	input_block_(block_size_, num_input_channels_),
	output_block_(block_size_, num_output_channels_),
	window_(new float[block_size_]),
	shift_amount_(shift_amount),
	callback_(callback) {
	RTC_CHECK_LE(num_output_channels_, num_input_channels_);
	RTC_CHECK_LE(shift_amount_, block_size_);

	memcpy(window_.get(), window, block_size_ * sizeof(*window_.get()));
	input_buffer_.MoveReadPositionBackward(initial_delay_);
	}

	Blocker::~Blocker() = default;

	// When block_size < chunk_size the input and output buffers look like this:
	//
	// delay* chunk_size chunk_size + delay*
	// buffer: <-------------\|---------------------\|---------------\|>
	// _a_ _b_ _c_
	//
	// On each call to ProcessChunk():
	// 1. New input gets read into sections _b_ and _c_ of the input buffer.
	// 2. We block starting from frame_offset.
	// 3. We block until we reach a block \|bl\| that doesn't contain any frames
	// from sections _a_ or _b_ of the input buffer.
	// 4. We window the current block, fire the callback for processing, window
	// again, and overlap/add to the output buffer.
	// 5. We copy sections _a_ and _b_ of the output buffer into output.
	// 6. For both the input and the output buffers, we copy section _c_ into
	// section _a_.
	// 7. We set the new frame_offset to be the difference between the first frame
	// of \|bl\| and the border between sections _b_ and _c_.
	//
	// When block_size > chunk_size the input and output buffers look like this:
	//
	// chunk_size delay* chunk_size + delay*
	// buffer: <-------------\|---------------------\|---------------\|>
	// _a_ _b_ _c_
	//
	// On each call to ProcessChunk():
	// The procedure is the same as above, except for:
	// 1. New input gets read into section _c_ of the input buffer.
	// 3. We block until we reach a block \|bl\| that doesn't contain any frames
	// from section _a_ of the input buffer.
	// 5. We copy section _a_ of the output buffer into output.
	// 6. For both the input and the output buffers, we copy sections _b_ and _c_
	// into section _a_ and _b_.
	// 7. We set the new frame_offset to be the difference between the first frame
	// of \|bl\| and the border between sections _a_ and _b_.
	//
	// * delay here refers to inintial_delay_
	//
	// TODO(claguna): Look at using ring buffers to eliminate some copies.
	void Blocker::ProcessChunk(const float* const* input,
	size_t chunk_size,
	size_t num_input_channels,
	size_t num_output_channels,
	float* const* output) {
	RTC_CHECK_EQ(chunk_size, chunk_size_);
	RTC_CHECK_EQ(num_input_channels, num_input_channels_);
	RTC_CHECK_EQ(num_output_channels, num_output_channels_);

	input_buffer_.Write(input, num_input_channels, chunk_size_);
	size_t first_frame_in_block = frame_offset_;

	// Loop through blocks.
	while (first_frame_in_block < chunk_size_) {
	input_buffer_.Read(input_block_.channels(), num_input_channels,
	block_size_);
	input_buffer_.MoveReadPositionBackward(block_size_ - shift_amount_);

	ApplyWindow(window_.get(),
	block_size_,
	num_input_channels_,
	input_block_.channels());
	callback_->ProcessBlock(input_block_.channels(),
	block_size_,
	num_input_channels_,
	num_output_channels_,
	output_block_.channels());
	ApplyWindow(window_.get(),
	block_size_,
	num_output_channels_,
	output_block_.channels());

	AddFrames(output_buffer_.channels(),
	first_frame_in_block,
	output_block_.channels(),
	0,
	block_size_,
	num_output_channels_,
	output_buffer_.channels(),
	first_frame_in_block);

	first_frame_in_block += shift_amount_;
	}

	// Copy output buffer to output
	CopyFrames(output_buffer_.channels(),
	0,
	chunk_size_,
	num_output_channels_,
	output,
	0);

	// Copy output buffer [chunk_size_, chunk_size_ + initial_delay]
	// to output buffer [0, initial_delay], zero the rest.
	MoveFrames(output_buffer_.channels(),
	chunk_size,
	initial_delay_,
	num_output_channels_,
	output_buffer_.channels(),
	0);
	ZeroOut(output_buffer_.channels(),
	initial_delay_,
	chunk_size_,
	num_output_channels_);

	// Calculate new starting frames.
	frame_offset_ = first_frame_in_block - chunk_size_;
	}

	} // namespace webrtc