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 15 #include "rtc_base/checks.h" 16 17 namespace webrtc { 18 namespace video_coding { Histogram(size_t num_buckets,size_t max_num_values)19Histogram::Histogram(size_t num_buckets, size_t max_num_values) { 20 RTC_DCHECK_GT(num_buckets, 0); 21 RTC_DCHECK_GT(max_num_values, 0); 22 buckets_.resize(num_buckets); 23 values_.reserve(max_num_values); 24 index_ = 0; 25 } 26 Add(size_t value)27void Histogram::Add(size_t value) { 28 value = std::min<size_t>(value, buckets_.size() - 1); 29 if (index_ < values_.size()) { 30 --buckets_[values_[index_]]; 31 RTC_DCHECK_LT(values_[index_], buckets_.size()); 32 values_[index_] = value; 33 } else { 34 values_.emplace_back(value); 35 } 36 37 ++buckets_[value]; 38 index_ = (index_ + 1) % values_.capacity(); 39 } 40 InverseCdf(float probability) const41size_t Histogram::InverseCdf(float probability) const { 42 RTC_DCHECK_GE(probability, 0.f); 43 RTC_DCHECK_LE(probability, 1.f); 44 RTC_DCHECK_GT(values_.size(), 0ul); 45 46 size_t bucket = 0; 47 float accumulated_probability = 0; 48 while (accumulated_probability < probability && bucket < buckets_.size()) { 49 accumulated_probability += 50 static_cast<float>(buckets_[bucket]) / values_.size(); 51 ++bucket; 52 } 53 return bucket; 54 } 55 NumValues() const56size_t Histogram::NumValues() const { 57 return values_.size(); 58 } 59 60 } // namespace video_coding 61 } // namespace webrtc 62