Bitrate controller for VideoToolbox encoder.

webrtc/modules/remote_bitrate_estimator/rate_statistics.cc

-/*
- *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/modules/remote_bitrate_estimator/rate_statistics.h"
-
-#include <assert.h>
-
-namespace webrtc {
-
-RateStatistics::RateStatistics(uint32_t window_size_ms, float scale)
-    : num_buckets_(window_size_ms + 1),  // N ms in (N+1) buckets.
-      buckets_(new size_t[num_buckets_]()),
-      accumulated_count_(0),
-      oldest_time_(0),
-      oldest_index_(0),
-      scale_(scale / (num_buckets_ - 1)) {
-}
-
-RateStatistics::~RateStatistics() {
-}
-
-void RateStatistics::Reset() {
-  accumulated_count_ = 0;
-  oldest_time_ = 0;
-  oldest_index_ = 0;
-  for (int i = 0; i < num_buckets_; i++) {
-    buckets_[i] = 0;
-  }
-}
-
-void RateStatistics::Update(size_t count, int64_t now_ms) {
-  if (now_ms < oldest_time_) {
-    // Too old data is ignored.
-    return;
-  }
-
-  EraseOld(now_ms);
-
-  int now_offset = static_cast<int>(now_ms - oldest_time_);
-  assert(now_offset < num_buckets_);
-  int index = oldest_index_ + now_offset;
-  if (index >= num_buckets_) {
-    index -= num_buckets_;
-  }
-  buckets_[index] += count;
-  accumulated_count_ += count;
-}
-
-uint32_t RateStatistics::Rate(int64_t now_ms) {
-  EraseOld(now_ms);
-  return static_cast<uint32_t>(accumulated_count_ * scale_ + 0.5f);
-}
-
-void RateStatistics::EraseOld(int64_t now_ms) {
-  int64_t new_oldest_time = now_ms - num_buckets_ + 1;
-  if (new_oldest_time <= oldest_time_) {
-    return;
-  }
-
-  while (oldest_time_ < new_oldest_time) {
-    size_t count_in_oldest_bucket = buckets_[oldest_index_];
-    assert(accumulated_count_ >= count_in_oldest_bucket);
-    accumulated_count_ -= count_in_oldest_bucket;
-    buckets_[oldest_index_] = 0;
-    if (++oldest_index_ >= num_buckets_) {
-      oldest_index_ = 0;
-    }
-    ++oldest_time_;
-    if (accumulated_count_ == 0) {
-      // This guarantees we go through all the buckets at most once, even if
-      // |new_oldest_time| is far greater than |oldest_time_|.
-      break;
-    }
-  }
-  oldest_time_ = new_oldest_time;
-}
-
-}  // namespace webrtc