| /* |
| * Copyright (c) 2012 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 "modules/audio_processing/high_pass_filter.h" |
| |
| #include <array> |
| #include <cstddef> |
| #include <vector> |
| |
| #include "api/array_view.h" |
| #include "modules/audio_processing/audio_buffer.h" |
| #include "modules/audio_processing/utility/cascaded_biquad_filter.h" |
| #include "rtc_base/checks.h" |
| |
| namespace webrtc { |
| |
| namespace { |
| // [B,A] = butter(2,100/8000,'high') |
| constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1> |
| kHighPassFilterCoefficients16kHz = {{ |
| {{0.972613898f, -1.945227797f, 0.972613898f}, |
| {-1.944477658f, 0.945977936f}}, |
| }}; |
| |
| // [B,A] = butter(2,100/16000,'high') |
| constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1> |
| kHighPassFilterCoefficients32kHz = {{ |
| {{0.986211925f, -1.972423849f, 0.986211925f}, |
| {-1.972233729f, 0.972613969f}}, |
| }}; |
| |
| // [B,A] = butter(2,100/24000,'high') |
| constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1> |
| kHighPassFilterCoefficients48kHz = {{ |
| {{0.990786698f, -1.981573396f, 0.990786698f}, |
| {-1.981488509f, 0.981658283f}}, |
| }}; |
| |
| ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients> ChooseCoefficients( |
| int sample_rate_hz) { |
| switch (sample_rate_hz) { |
| case 16000: |
| return ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients>( |
| kHighPassFilterCoefficients16kHz); |
| case 32000: |
| return ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients>( |
| kHighPassFilterCoefficients32kHz); |
| case 48000: |
| return ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients>( |
| kHighPassFilterCoefficients48kHz); |
| default: |
| RTC_DCHECK_NOTREACHED(); |
| } |
| RTC_DCHECK_NOTREACHED(); |
| return ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients>( |
| kHighPassFilterCoefficients16kHz); |
| } |
| |
| } // namespace |
| |
| HighPassFilter::HighPassFilter(int sample_rate_hz, size_t num_channels) |
| : sample_rate_hz_(sample_rate_hz) { |
| filters_.resize(num_channels); |
| auto coefficients = ChooseCoefficients(sample_rate_hz_); |
| for (size_t k = 0; k < filters_.size(); ++k) { |
| filters_[k].reset(new CascadedBiQuadFilter(coefficients)); |
| } |
| } |
| |
| HighPassFilter::~HighPassFilter() = default; |
| |
| void HighPassFilter::Process(AudioBuffer* audio, bool use_split_band_data) { |
| RTC_DCHECK(audio); |
| RTC_DCHECK_EQ(filters_.size(), audio->num_channels()); |
| if (use_split_band_data) { |
| for (size_t k = 0; k < audio->num_channels(); ++k) { |
| ArrayView<float> channel_data = ArrayView<float>( |
| audio->split_bands(k)[0], audio->num_frames_per_band()); |
| filters_[k]->Process(channel_data); |
| } |
| } else { |
| for (size_t k = 0; k < audio->num_channels(); ++k) { |
| ArrayView<float> channel_data = |
| ArrayView<float>(&audio->channels()[k][0], audio->num_frames()); |
| filters_[k]->Process(channel_data); |
| } |
| } |
| } |
| |
| void HighPassFilter::Process(std::vector<std::vector<float>>* audio) { |
| RTC_DCHECK_EQ(filters_.size(), audio->size()); |
| for (size_t k = 0; k < audio->size(); ++k) { |
| filters_[k]->Process((*audio)[k]); |
| } |
| } |
| |
| void HighPassFilter::Reset() { |
| for (size_t k = 0; k < filters_.size(); ++k) { |
| filters_[k]->Reset(); |
| } |
| } |
| |
| void HighPassFilter::Reset(size_t num_channels) { |
| const size_t old_num_channels = filters_.size(); |
| filters_.resize(num_channels); |
| if (filters_.size() < old_num_channels) { |
| Reset(); |
| } else { |
| for (size_t k = 0; k < old_num_channels; ++k) { |
| filters_[k]->Reset(); |
| } |
| const auto& coefficients = ChooseCoefficients(sample_rate_hz_); |
| for (size_t k = old_num_channels; k < filters_.size(); ++k) { |
| filters_[k].reset(new CascadedBiQuadFilter(coefficients)); |
| } |
| } |
| } |
| |
| } // namespace webrtc |