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c2a82417e9
Bug: b/358039777 Change-Id: Id191d584e22cf82384a5d16ed355f41c0bb32b7b Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/358981 Reviewed-by: Erik Språng <sprang@webrtc.org> Commit-Queue: Fanny Linderborg <linderborg@webrtc.org> Cr-Commit-Position: refs/heads/main@{#42764}
66 lines
1.8 KiB
C++
66 lines
1.8 KiB
C++
/*
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* Copyright 2024 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 "video/corruption_detection/halton_sequence.h"
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#include <algorithm>
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#include <vector>
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#include "rtc_base/checks.h"
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namespace webrtc {
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namespace {
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static constexpr int kMaxDimensions = 5;
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const int kBases[kMaxDimensions] = {2, 3, 5, 7, 11};
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double GetVanDerCorputSequenceElement(int sequence_idx, int base) {
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if (sequence_idx < 0 || base < 2) {
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sequence_idx = 0;
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base = 2;
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}
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double element = 0.0;
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double positional_value = 1.0;
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int left = sequence_idx;
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while (left > 0) {
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positional_value /= base;
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element += positional_value * (left % base);
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left /= base;
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}
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return element;
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}
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} // namespace
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HaltonSequence::HaltonSequence(int num_dimensions)
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: num_dimensions_(num_dimensions), current_idx_(0) {
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RTC_CHECK_GE(num_dimensions_, 1)
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<< "num_dimensions must be >= 1. Will be set to 1.";
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RTC_CHECK_LE(num_dimensions_, kMaxDimensions)
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<< "num_dimensions must be <= " << kMaxDimensions << ". Will be set to "
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<< kMaxDimensions << ".";
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num_dimensions_ = std::clamp(num_dimensions_, 1, kMaxDimensions);
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}
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std::vector<double> HaltonSequence::GetNext() {
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std::vector<double> point = {};
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point.reserve(num_dimensions_);
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for (int i = 0; i < num_dimensions_; ++i) {
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point.push_back(GetVanDerCorputSequenceElement(current_idx_, kBases[i]));
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}
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++current_idx_;
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return point;
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}
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void HaltonSequence::Reset() {
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HaltonSequence::current_idx_ = 0;
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}
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} // namespace webrtc
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