histogram.cc (1703B)
1 /* 2 * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 #include "modules/video_coding/histogram.h" 12 13 #include <algorithm> 14 #include <cstddef> 15 16 #include "rtc_base/checks.h" 17 18 namespace webrtc { 19 namespace video_coding { 20 Histogram::Histogram(size_t num_buckets, size_t max_num_values) { 21 RTC_DCHECK_GT(num_buckets, 0); 22 RTC_DCHECK_GT(max_num_values, 0); 23 buckets_.resize(num_buckets); 24 values_.reserve(max_num_values); 25 index_ = 0; 26 } 27 28 void Histogram::Add(size_t value) { 29 value = std::min<size_t>(value, buckets_.size() - 1); 30 if (index_ < values_.size()) { 31 --buckets_[values_[index_]]; 32 RTC_DCHECK_LT(values_[index_], buckets_.size()); 33 values_[index_] = value; 34 } else { 35 values_.emplace_back(value); 36 } 37 38 ++buckets_[value]; 39 index_ = (index_ + 1) % values_.capacity(); 40 } 41 42 size_t Histogram::InverseCdf(float probability) const { 43 RTC_DCHECK_GE(probability, 0.f); 44 RTC_DCHECK_LE(probability, 1.f); 45 RTC_DCHECK_GT(values_.size(), 0ul); 46 47 size_t bucket = 0; 48 float accumulated_probability = 0; 49 while (accumulated_probability < probability && bucket < buckets_.size()) { 50 accumulated_probability += 51 static_cast<float>(buckets_[bucket]) / values_.size(); 52 ++bucket; 53 } 54 return bucket; 55 } 56 57 size_t Histogram::NumValues() const { 58 return values_.size(); 59 } 60 61 } // namespace video_coding 62 } // namespace webrtc