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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "third_party/blink/renderer/platform/audio/fft_convolver.h"
#include "base/compiler_specific.h"
#include "third_party/blink/renderer/platform/audio/vector_math.h"
namespace blink {
FFTConvolver::FFTConvolver(unsigned fft_size)
: frame_(fft_size),
read_write_index_(0),
input_buffer_(fft_size), // 2nd half of buffer is always zeroed
output_buffer_(fft_size),
last_overlap_buffer_(fft_size / 2) {}
void FFTConvolver::Process(const FFTFrame* fft_kernel,
const float* source_p,
float* dest_p,
uint32_t frames_to_process) {
unsigned half_size = FftSize() / 2;
// framesToProcess must be an exact multiple of halfSize,
// or halfSize is a multiple of framesToProcess when halfSize >
// framesToProcess.
bool is_good =
!(half_size % frames_to_process && frames_to_process % half_size);
DCHECK(is_good);
size_t number_of_divisions =
half_size <= frames_to_process ? (frames_to_process / half_size) : 1;
size_t division_size =
number_of_divisions == 1 ? frames_to_process : half_size;
for (size_t i = 0; i < number_of_divisions; ++i,
UNSAFE_TODO(source_p += division_size),
UNSAFE_TODO(dest_p += division_size)) {
// Copy samples to input buffer (note contraint above!)
float* input_p = input_buffer_.Data();
DCHECK(source_p);
DCHECK(input_p);
DCHECK_LE(read_write_index_ + division_size, input_buffer_.size());
UNSAFE_TODO(memcpy(input_p + read_write_index_, source_p,
sizeof(float) * division_size));
// Copy samples from output buffer
float* output_p = output_buffer_.Data();
DCHECK(dest_p);
DCHECK(output_p);
DCHECK_LE(read_write_index_ + division_size, output_buffer_.size());
UNSAFE_TODO(memcpy(dest_p, output_p + read_write_index_,
sizeof(float) * division_size));
read_write_index_ += division_size;
// Check if it's time to perform the next FFT
if (read_write_index_ == half_size) {
// The input buffer is now filled (get frequency-domain version)
frame_.DoFFT(input_buffer_.Data());
frame_.Multiply(*fft_kernel);
frame_.DoInverseFFT(output_buffer_.Data());
// Overlap-add 1st half from previous time
vector_math::Vadd(output_buffer_.Data(), 1, last_overlap_buffer_.Data(),
1, output_buffer_.Data(), 1, half_size);
// Finally, save 2nd half of result
DCHECK_EQ(output_buffer_.size(), 2 * half_size);
DCHECK_EQ(last_overlap_buffer_.size(), half_size);
UNSAFE_TODO(memcpy(last_overlap_buffer_.Data(),
output_buffer_.Data() + half_size,
sizeof(float) * half_size));
// Reset index back to start for next time
read_write_index_ = 0;
}
}
}
void FFTConvolver::Reset() {
last_overlap_buffer_.Zero();
read_write_index_ = 0;
}
} // namespace blink
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