BiQuadFilter: API improvements
Bug: webrtc:7494 Change-Id: If0270cddeb46fa53c0fbb385c85e48f28f9e1a5c Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/236342 Reviewed-by: Hanna Silen <silen@webrtc.org> Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Cr-Commit-Position: refs/heads/main@{#35274}
This commit is contained in:
Alessio Bazzica
WebRTC LUCI CQ
parent
32c4ecb3db
commit
2bf6d45f14
@ -10,26 +10,37 @@
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#include "modules/audio_processing/agc2/biquad_filter.h"
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#include <stddef.h>
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#include "rtc_base/arraysize.h"
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namespace webrtc {
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// Transposed direct form I implementation of a bi-quad filter applied to an
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// input signal `x` to produce an output signal `y`.
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BiQuadFilter::BiQuadFilter(const Config& config)
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: config_(config), state_({}) {}
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BiQuadFilter::~BiQuadFilter() = default;
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void BiQuadFilter::SetConfig(const Config& config) {
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config_ = config;
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state_ = {};
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}
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void BiQuadFilter::Reset() {
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state_ = {};
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}
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void BiQuadFilter::Process(rtc::ArrayView<const float> x,
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rtc::ArrayView<float> y) {
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RTC_DCHECK_EQ(x.size(), y.size());
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for (size_t k = 0; k < x.size(); ++k) {
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// Use temporary variable for x[k] to allow in-place function call
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// (that x and y refer to the same array).
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// Use a temporary variable for `x[k]` to allow in-place processing.
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const float tmp = x[k];
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y[k] = coefficients_.b[0] * tmp + coefficients_.b[1] * biquad_state_.b[0] +
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coefficients_.b[2] * biquad_state_.b[1] -
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coefficients_.a[0] * biquad_state_.a[0] -
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coefficients_.a[1] * biquad_state_.a[1];
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biquad_state_.b[1] = biquad_state_.b[0];
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biquad_state_.b[0] = tmp;
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biquad_state_.a[1] = biquad_state_.a[0];
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biquad_state_.a[0] = y[k];
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y[k] = config_.b[0] * tmp + config_.b[1] * state_.b[0] +
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config_.b[2] * state_.b[1] - config_.a[0] * state_.a[0] -
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config_.a[1] * state_.a[1];
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state_.b[1] = state_.b[0];
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state_.b[0] = tmp;
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state_.a[1] = state_.a[0];
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state_.a[0] = y[k];
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}
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}
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@ -11,54 +11,44 @@
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#ifndef MODULES_AUDIO_PROCESSING_AGC2_BIQUAD_FILTER_H_
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#define MODULES_AUDIO_PROCESSING_AGC2_BIQUAD_FILTER_H_
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#include <algorithm>
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#include "api/array_view.h"
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#include "rtc_base/arraysize.h"
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#include "rtc_base/constructor_magic.h"
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namespace webrtc {
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// Transposed direct form I implementation of a bi-quad filter.
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// b[0] + b[1] • z^(-1) + b[2] • z^(-2)
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// H(z) = ------------------------------------
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// 1 + a[1] • z^(-1) + a[2] • z^(-2)
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class BiQuadFilter {
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public:
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// Normalized filter coefficients.
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// b_0 + b_1 • z^(-1) + b_2 • z^(-2)
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// H(z) = ---------------------------------
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// 1 + a_1 • z^(-1) + a_2 • z^(-2)
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struct BiQuadCoefficients {
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float b[3];
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float a[2];
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// Computed as `[b, a] = scipy.signal.butter(N=2, Wn, btype)`.
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struct Config {
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float b[3]; // b[0], b[1], b[2].
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float a[2]; // a[1], a[2].
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};
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BiQuadFilter() = default;
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explicit BiQuadFilter(const Config& config);
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BiQuadFilter(const BiQuadFilter&) = delete;
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BiQuadFilter& operator=(const BiQuadFilter&) = delete;
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~BiQuadFilter();
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void Initialize(const BiQuadCoefficients& coefficients) {
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coefficients_ = coefficients;
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}
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// Sets the filter configuration and resets the internal state.
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void SetConfig(const Config& config);
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void Reset() { biquad_state_.Reset(); }
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// Zeroes the filter state.
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void Reset();
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// Produces a filtered output y of the input x. Both x and y need to
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// have the same length. In-place modification is allowed.
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// Filters `x` and writes the output in `y`, which must have the same length
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// of `x`. In-place processing is supported.
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void Process(rtc::ArrayView<const float> x, rtc::ArrayView<float> y);
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private:
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struct BiQuadState {
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BiQuadState() { Reset(); }
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void Reset() {
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std::fill(b, b + arraysize(b), 0.f);
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std::fill(a, a + arraysize(a), 0.f);
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}
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Config config_;
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struct State {
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float b[2];
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float a[2];
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};
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BiQuadState biquad_state_;
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BiQuadCoefficients coefficients_;
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RTC_DISALLOW_COPY_AND_ASSIGN(BiQuadFilter);
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} state_;
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};
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} // namespace webrtc
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@ -19,11 +19,10 @@
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#include "rtc_base/gunit.h"
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namespace webrtc {
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namespace test {
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namespace {
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constexpr size_t kFrameSize = 8;
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constexpr size_t kNumFrames = 4;
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constexpr int kFrameSize = 8;
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constexpr int kNumFrames = 4;
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using FloatArraySequence =
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std::array<std::array<float, kFrameSize>, kNumFrames>;
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@ -37,8 +36,8 @@ constexpr FloatArraySequence kBiQuadInputSeq = {
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{{22.645832f, -64.597153f, 55.462521f, -109.393188f, 10.117825f,
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-40.019642f, -98.612228f, -8.330326f}}}};
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// Generated via "B, A = scipy.signal.butter(2, 30/12000, btype='highpass')"
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const BiQuadFilter::BiQuadCoefficients kBiQuadConfig = {
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// Computed as `scipy.signal.butter(N=2, Wn=60/24000, btype='highpass')`.
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constexpr BiQuadFilter::Config kBiQuadConfig{
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{0.99446179f, -1.98892358f, 0.99446179f},
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{-1.98889291f, 0.98895425f}};
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@ -57,22 +56,23 @@ constexpr FloatArraySequence kBiQuadOutputSeq = {
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{{24.84286614f, -62.18094158f, 57.91488056f, -106.65685933f, 13.38760103f,
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-36.60367134f, -94.44880104f, -3.59920354f}}}};
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// Fail for every pair from two equally sized rtc::ArrayView<float> views such
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// Fails for every pair from two equally sized rtc::ArrayView<float> views such
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// that their relative error is above a given threshold. If the expected value
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// of a pair is 0, the tolerance is used to check the absolute error.
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// of a pair is 0, `tolerance` is used to check the absolute error.
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void ExpectNearRelative(rtc::ArrayView<const float> expected,
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rtc::ArrayView<const float> computed,
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const float tolerance) {
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// The relative error is undefined when the expected value is 0.
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// When that happens, check the absolute error instead. `safe_den` is used
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// below to implement such logic.
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auto safe_den = [](float x) { return (x == 0.f) ? 1.f : std::fabs(x); };
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auto safe_den = [](float x) { return (x == 0.0f) ? 1.0f : std::fabs(x); };
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ASSERT_EQ(expected.size(), computed.size());
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for (size_t i = 0; i < expected.size(); ++i) {
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const float abs_diff = std::fabs(expected[i] - computed[i]);
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// No failure when the values are equal.
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if (abs_diff == 0.f)
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if (abs_diff == 0.0f) {
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continue;
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}
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SCOPED_TRACE(i);
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SCOPED_TRACE(expected[i]);
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SCOPED_TRACE(computed[i]);
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@ -80,32 +80,32 @@ void ExpectNearRelative(rtc::ArrayView<const float> expected,
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}
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}
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} // namespace
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// Checks that filtering works when different containers are used both as input
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// and as output.
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TEST(BiQuadFilterTest, FilterNotInPlace) {
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BiQuadFilter filter;
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filter.Initialize(kBiQuadConfig);
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BiQuadFilter filter(kBiQuadConfig);
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std::array<float, kFrameSize> samples;
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// TODO(https://bugs.webrtc.org/8948): Add when the issue is fixed.
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// FloatingPointExceptionObserver fpe_observer;
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for (size_t i = 0; i < kNumFrames; ++i) {
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for (int i = 0; i < kNumFrames; ++i) {
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SCOPED_TRACE(i);
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filter.Process(kBiQuadInputSeq[i], samples);
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ExpectNearRelative(kBiQuadOutputSeq[i], samples, 2e-4f);
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}
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}
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// Checks that filtering works when the same container is used both as input and
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// as output.
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TEST(BiQuadFilterTest, FilterInPlace) {
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BiQuadFilter filter;
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filter.Initialize(kBiQuadConfig);
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BiQuadFilter filter(kBiQuadConfig);
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std::array<float, kFrameSize> samples;
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// TODO(https://bugs.webrtc.org/8948): Add when the issue is fixed.
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// FloatingPointExceptionObserver fpe_observer;
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for (size_t i = 0; i < kNumFrames; ++i) {
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for (int i = 0; i < kNumFrames; ++i) {
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SCOPED_TRACE(i);
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std::copy(kBiQuadInputSeq[i].begin(), kBiQuadInputSeq[i].end(),
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samples.begin());
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@ -114,23 +114,62 @@ TEST(BiQuadFilterTest, FilterInPlace) {
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}
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}
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TEST(BiQuadFilterTest, Reset) {
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BiQuadFilter filter;
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filter.Initialize(kBiQuadConfig);
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// Checks that different configurations produce different outputs.
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TEST(BiQuadFilterTest, SetConfigDifferentOutput) {
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BiQuadFilter filter(/*config=*/{{0.97803048f, -1.95606096f, 0.97803048f},
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{-1.95557824f, 0.95654368f}});
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std::array<float, kFrameSize> samples1;
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for (size_t i = 0; i < kNumFrames; ++i) {
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples1);
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}
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filter.Reset();
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filter.SetConfig(
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{{0.09763107f, 0.19526215f, 0.09763107f}, {-0.94280904f, 0.33333333f}});
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std::array<float, kFrameSize> samples2;
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for (size_t i = 0; i < kNumFrames; ++i) {
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples2);
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}
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EXPECT_NE(samples1, samples2);
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}
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// Checks that when `SetConfig()` is called but the filter coefficients are the
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// same the filter state is reset.
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TEST(BiQuadFilterTest, SetConfigResetsState) {
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BiQuadFilter filter(kBiQuadConfig);
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std::array<float, kFrameSize> samples1;
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples1);
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}
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filter.SetConfig(kBiQuadConfig);
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std::array<float, kFrameSize> samples2;
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples2);
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}
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EXPECT_EQ(samples1, samples2);
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}
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} // namespace test
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// Checks that when `Reset()` is called the filter state is reset.
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TEST(BiQuadFilterTest, Reset) {
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BiQuadFilter filter(kBiQuadConfig);
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std::array<float, kFrameSize> samples1;
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples1);
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}
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filter.Reset();
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std::array<float, kFrameSize> samples2;
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for (int i = 0; i < kNumFrames; ++i) {
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filter.Process(kBiQuadInputSeq[i], samples2);
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}
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EXPECT_EQ(samples1, samples2);
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}
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} // namespace
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} // namespace webrtc
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@ -19,8 +19,8 @@ namespace webrtc {
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namespace rnn_vad {
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namespace {
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// Generated via "B, A = scipy.signal.butter(2, 30/12000, btype='highpass')"
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const BiQuadFilter::BiQuadCoefficients kHpfConfig24k = {
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// Computed as `scipy.signal.butter(N=2, Wn=60/24000, btype='highpass')`.
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constexpr BiQuadFilter::Config kHpfConfig24k{
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{0.99446179f, -1.98892358f, 0.99446179f},
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{-1.98889291f, 0.98895425f}};
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@ -28,6 +28,7 @@ const BiQuadFilter::BiQuadCoefficients kHpfConfig24k = {
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FeaturesExtractor::FeaturesExtractor(const AvailableCpuFeatures& cpu_features)
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: use_high_pass_filter_(false),
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hpf_(kHpfConfig24k),
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pitch_buf_24kHz_(),
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pitch_buf_24kHz_view_(pitch_buf_24kHz_.GetBufferView()),
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lp_residual_(kBufSize24kHz),
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@ -35,7 +36,6 @@ FeaturesExtractor::FeaturesExtractor(const AvailableCpuFeatures& cpu_features)
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pitch_estimator_(cpu_features),
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reference_frame_view_(pitch_buf_24kHz_.GetMostRecentValuesView()) {
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RTC_DCHECK_EQ(kBufSize24kHz, lp_residual_.size());
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hpf_.Initialize(kHpfConfig24k);
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Reset();
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}
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@ -44,8 +44,9 @@ FeaturesExtractor::~FeaturesExtractor() = default;
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void FeaturesExtractor::Reset() {
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pitch_buf_24kHz_.Reset();
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spectral_features_extractor_.Reset();
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if (use_high_pass_filter_)
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if (use_high_pass_filter_) {
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hpf_.Reset();
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}
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}
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bool FeaturesExtractor::CheckSilenceComputeFeatures(
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