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Diffstat (limited to 'third_party/libwebrtc/modules/audio_processing/agc2/biquad_filter.cc')
-rw-r--r-- | third_party/libwebrtc/modules/audio_processing/agc2/biquad_filter.cc | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/agc2/biquad_filter.cc b/third_party/libwebrtc/modules/audio_processing/agc2/biquad_filter.cc new file mode 100644 index 0000000000..c1b80d7320 --- /dev/null +++ b/third_party/libwebrtc/modules/audio_processing/agc2/biquad_filter.cc @@ -0,0 +1,60 @@ +/* + * Copyright (c) 2016 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/agc2/biquad_filter.h" + +#include "rtc_base/arraysize.h" + +namespace webrtc { + +BiQuadFilter::BiQuadFilter(const Config& config) + : config_(config), state_({}) {} + +BiQuadFilter::~BiQuadFilter() = default; + +void BiQuadFilter::SetConfig(const Config& config) { + config_ = config; + state_ = {}; +} + +void BiQuadFilter::Reset() { + state_ = {}; +} + +void BiQuadFilter::Process(rtc::ArrayView<const float> x, + rtc::ArrayView<float> y) { + RTC_DCHECK_EQ(x.size(), y.size()); + const float config_a0 = config_.a[0]; + const float config_a1 = config_.a[1]; + const float config_b0 = config_.b[0]; + const float config_b1 = config_.b[1]; + const float config_b2 = config_.b[2]; + float state_a0 = state_.a[0]; + float state_a1 = state_.a[1]; + float state_b0 = state_.b[0]; + float state_b1 = state_.b[1]; + for (size_t k = 0, x_size = x.size(); k < x_size; ++k) { + // Use a temporary variable for `x[k]` to allow in-place processing. + const float tmp = x[k]; + float y_k = config_b0 * tmp + config_b1 * state_b0 + config_b2 * state_b1 - + config_a0 * state_a0 - config_a1 * state_a1; + state_b1 = state_b0; + state_b0 = tmp; + state_a1 = state_a0; + state_a0 = y_k; + y[k] = y_k; + } + state_.a[0] = state_a0; + state_.a[1] = state_a1; + state_.b[0] = state_b0; + state_.b[1] = state_b1; +} + +} // namespace webrtc |