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92ea95e34a
In https://webrtc-review.googlesource.com/c/src/+/1560 we moved WebRTC from src/webrtc to src/ (in order to preserve an healthy git history). This CL takes care of fixing header guards, #include paths, etc... NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true TBR=tommi@webrtc.org Bug: chromium:611808 Change-Id: Iea91618212bee0af16aa3f05071eab8f93706578 Reviewed-on: https://webrtc-review.googlesource.com/1561 Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Reviewed-by: Henrik Kjellander <kjellander@webrtc.org> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19846}
44 lines
1.3 KiB
C++
44 lines
1.3 KiB
C++
/*
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* Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/audio_processing/aec3/decimator_by_4.h"
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#include "rtc_base/checks.h"
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namespace webrtc {
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namespace {
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// [B,A] = butter(2,1500/16000) which are the same as [B,A] =
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// butter(2,750/8000).
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const CascadedBiQuadFilter::BiQuadCoefficients kLowPassFilterCoefficients = {
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{0.0179f, 0.0357f, 0.0179f},
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{-1.5879f, 0.6594f}};
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} // namespace
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DecimatorBy4::DecimatorBy4()
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: low_pass_filter_(kLowPassFilterCoefficients, 3) {}
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void DecimatorBy4::Decimate(rtc::ArrayView<const float> in,
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rtc::ArrayView<float> out) {
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RTC_DCHECK_EQ(kBlockSize, in.size());
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RTC_DCHECK_EQ(kSubBlockSize, out.size());
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std::array<float, kBlockSize> x;
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// Limit the frequency content of the signal to avoid aliasing.
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low_pass_filter_.Process(in, x);
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// Downsample the signal.
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for (size_t j = 0, k = 0; j < out.size(); ++j, k += 4) {
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RTC_DCHECK_GT(kBlockSize, k);
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out[j] = x[k];
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}
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}
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} // namespace webrtc
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