diff options
Diffstat (limited to 'src/3rdparty/resonance-audio/resonance_audio/dsp/delay_filter.cc')
| -rw-r--r-- | src/3rdparty/resonance-audio/resonance_audio/dsp/delay_filter.cc | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/src/3rdparty/resonance-audio/resonance_audio/dsp/delay_filter.cc b/src/3rdparty/resonance-audio/resonance_audio/dsp/delay_filter.cc new file mode 100644 index 000000000..b448de58b --- /dev/null +++ b/src/3rdparty/resonance-audio/resonance_audio/dsp/delay_filter.cc @@ -0,0 +1,180 @@ +/* +Copyright 2018 Google Inc. All Rights Reserved. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS-IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +#include "dsp/delay_filter.h" + +#include <cmath> + +#include "base/constants_and_types.h" +#include "base/misc_math.h" + + +namespace vraudio { +// The following explains the behaviour of the delay line when a change to the +// delay length is made. Initially |delay| is 2, |frames_per_buffer_| +// is 4, and |delay_line_| is 8 in length. +// +// delay = 2 +// +// input0 [1, 2, 3, 4] output0 [0, 0, 1, 2] +// +// 0 1 2 3 4 5 6 7 +// delay line [1, 2, 3, 4, 0, 0, 0, 0] +// | | +// w r +// ---------------------------------------------------------- +// +// delay = 2 +// +// input1 [5, 6, 7, 8] output1 [3, 4, 5, 6] +// +// 0 1 2 3 4 5 6 7 +// delay line [1, 2, 3, 4, 5, 6, 7, 8] +// | | +// w r +// ---------------------------------------------------------- +// +// delay = 1 +// +// 0 1 2 3 4 5 6 7 +// delay line [1, 2, 3, 4, 5, 6, 7, 8] +// | | +// w r +// ---------------------------------------------------------- +// +// delay = 1 +// +// input2 [9, 10, 11, 12] output2 [8, 9, 10, 11] +// +// 0 1 2 3 4 5 6 7 +// delay line [9, 10, 11, 12, 5, 6, 7, 8] +// | | +// w r +// ---------------------------------------------------------- + +DelayFilter::DelayFilter(size_t max_delay_length, size_t frames_per_buffer) + : frames_per_buffer_(frames_per_buffer), + delay_line_(nullptr), + write_cursor_(0) { + DCHECK_GT(frames_per_buffer_, 0U); + SetMaximumDelay(max_delay_length); +} + +void DelayFilter::SetMaximumDelay(size_t max_delay_length) { + max_delay_length_ = max_delay_length; + const size_t new_buffer_size = frames_per_buffer_ + max_delay_length_; + + if (delay_line_ == nullptr) { + delay_line_.reset(new AudioBuffer(kNumMonoChannels, new_buffer_size)); + delay_line_->Clear(); + return; + } + AudioBuffer::Channel* delay_channel = &(*delay_line_)[0]; + // If |delay_line_| is not large enough, resize. + const size_t current_buffer_size = delay_line_->num_frames(); + if (max_delay_length_ > current_buffer_size - frames_per_buffer_) { + // Allocate |new_delay_line| and populate it with the current |delay_line_| + // data, so that replacing the buffer does not affect the already stored + // samples. + auto new_delay_line = std::unique_ptr<AudioBuffer>( + new AudioBuffer(kNumMonoChannels, new_buffer_size)); + new_delay_line->Clear(); + std::copy(delay_channel->begin() + write_cursor_, delay_channel->end(), + (*new_delay_line)[0].begin()); + if (write_cursor_ > 0) { + // Positive |write_cursor_| means that we still have remaining samples to + // be moved to |new_delay_line_| all of which reside left of the cursor. + std::copy( + delay_channel->begin(), delay_channel->begin() + write_cursor_, + (*new_delay_line)[0].begin() + current_buffer_size - write_cursor_); + write_cursor_ = current_buffer_size; + } + delay_line_ = std::move(new_delay_line); + } +} + +void DelayFilter::InsertData(const AudioBuffer::Channel& input) { + + DCHECK_EQ(input.size(), frames_per_buffer_); + + const size_t delay_buffer_size = delay_line_->num_frames(); + + // Record the remaining space in the |delay_line_| after the write cursor. + const size_t remaining_size_write = delay_buffer_size - write_cursor_; + AudioBuffer::Channel* delay_channel = &(*delay_line_)[0]; + + // Copy the input into the delay line. + if (remaining_size_write >= frames_per_buffer_) { + DCHECK_LE(delay_channel->begin() + write_cursor_ + frames_per_buffer_, + delay_channel->end()); + std::copy(input.begin(), input.end(), + delay_channel->begin() + write_cursor_); + } else { + DCHECK_LE(delay_channel->begin() + write_cursor_ + remaining_size_write, + delay_channel->end()); + DCHECK_LE(input.begin() + remaining_size_write, input.end()); + std::copy(input.begin(), input.begin() + remaining_size_write, + delay_channel->begin() + write_cursor_); + DCHECK_LE(delay_channel->begin() + remaining_size_write, + delay_channel->end()); + std::copy(input.begin() + remaining_size_write, input.end(), + delay_channel->begin()); + } + + write_cursor_ = (write_cursor_ + frames_per_buffer_) % delay_buffer_size; +} + +void DelayFilter::GetDelayedData(size_t delay_samples, + AudioBuffer::Channel* buffer) { + + DCHECK(buffer); + DCHECK_GE(delay_samples, 0U); + DCHECK_LE(delay_samples, max_delay_length_); + + const size_t delay_buffer_size = delay_line_->num_frames(); + // Position in the delay line to begin reading from. + DCHECK_GE(write_cursor_ + delay_buffer_size, + delay_samples + frames_per_buffer_); + const size_t read_cursor = + (write_cursor_ + delay_buffer_size - delay_samples - frames_per_buffer_) % + delay_buffer_size; + // Record the remaining space in the |delay_line_| after the read cursor. + const size_t remaining_size_read = delay_buffer_size - read_cursor; + AudioBuffer::Channel* delay_channel = &(*delay_line_)[0]; + + // Extract a portion of the delay line into the buffer. + if (remaining_size_read >= frames_per_buffer_) { + DCHECK_LE(buffer->begin() + frames_per_buffer_, buffer->end()); + DCHECK_LE(delay_channel->begin() + read_cursor + frames_per_buffer_, + delay_channel->end()); + std::copy(delay_channel->begin() + read_cursor, + delay_channel->begin() + read_cursor + frames_per_buffer_, + buffer->begin()); + } else { + DCHECK_LE(buffer->begin() + delay_channel->size() - read_cursor, + buffer->end()); + std::copy(delay_channel->begin() + read_cursor, delay_channel->end(), + buffer->begin()); + DCHECK_LE(buffer->begin() + frames_per_buffer_, buffer->end()); + DCHECK_LE(delay_channel->begin() + frames_per_buffer_ - remaining_size_read, + delay_channel->end()); + std::copy(delay_channel->begin(), + delay_channel->begin() + frames_per_buffer_ - remaining_size_read, + buffer->begin() + remaining_size_read); + } +} + +} // namespace vraudio |