BWE allocation strategy

webrtc/rtc_base/bitrateallocationstrategy.cc

Index: webrtc/rtc_base/bitrateallocationstrategy.cc
diff --git a/webrtc/rtc_base/bitrateallocationstrategy.cc b/webrtc/rtc_base/bitrateallocationstrategy.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ac15a2fb5ec9e4c98b515c11cbbdf27b1fa9c3e5
--- /dev/null
+++ b/webrtc/rtc_base/bitrateallocationstrategy.cc
@@ -0,0 +1,112 @@
+/*
+ *  Copyright 2017 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/rtc_base/bitrateallocationstrategy.h"
+#include <algorithm>
+#include <utility>
+
+namespace rtc {
+
+BitrateAllocationStrategy::TrackAllocations
+BitrateAllocationStrategy::SetAllBitratesToMinimum(
+    const TrackConfigs& track_configs) {
+  TrackAllocations track_allocations;
+  for (const auto& track_config : track_configs) {
+    track_allocations[track_config.second.track_id] =
+        track_config.second.min_bitrate_bps;
+  }
+  return track_allocations;
+}
+
+BitrateAllocationStrategy::TrackAllocations
+BitrateAllocationStrategy::DistributeBitratesEvenly(
+    const TrackConfigs& track_configs,
+    uint32_t available_bitrate) {
+  TrackAllocations track_allocations = SetAllBitratesToMinimum(track_configs);
+  uint32_t sum_min_bitrates = 0;
+  uint32_t sum_max_bitrates = 0;
+  for (const auto& track_config : track_configs) {
+    sum_min_bitrates += track_config.second.min_bitrate_bps;
+    sum_max_bitrates += track_config.second.max_bitrate_bps;
+  }
+  if (sum_min_bitrates >= available_bitrate) {
+    return track_allocations;
+  } else if (available_bitrate >= sum_max_bitrates) {
+    for (const auto& track_config : track_configs) {
+      track_allocations[track_config.second.track_id] =
+          track_config.second.max_bitrate_bps;
+    }
+    return track_allocations;
+  } else {
+    std::multimap<uint32_t, TrackConfig> max_bitrate_sorted_configs;
+    for (const auto& track_config : track_configs) {
+      max_bitrate_sorted_configs.insert(std::pair<uint32_t, const TrackConfig&>(
+          track_config.second.max_bitrate_bps, track_config.second));
+    }
+    uint32_t total_available_increase = (available_bitrate - sum_min_bitrates);
+    int processed_configs = 0;
+    for (const auto& track_config_pair : max_bitrate_sorted_configs) {
+      TrackConfig track_config = track_config_pair.second;
+      uint32_t available_increase =
+          total_available_increase /
+          (static_cast<uint32_t>(track_configs.size() - processed_configs));
+      uint32_t consumed_increase =
+          std::min(track_config.max_bitrate_bps, available_increase);
+      track_allocations[track_config.track_id] += consumed_increase;
+      total_available_increase -= consumed_increase;
+      ++processed_configs;
+    }
+    return track_allocations;
+  }
+}
+
+AudioPriorityBitrateAllocationStrategy::AudioPriorityBitrateAllocationStrategy(
+    std::string audio_track_id,
+    uint32_t sufficient_audio_bitrate)
+    : audio_track_id_(audio_track_id),
+      sufficient_audio_bitrate_(sufficient_audio_bitrate) {}
+
+BitrateAllocationStrategy::TrackAllocations
+AudioPriorityBitrateAllocationStrategy::AllocateBitrates(
+    uint32_t available_bitrate,
+    const TrackConfigs& track_configs) {
+  auto audio_track_config_pair = track_configs.find(audio_track_id_);
+  const TrackConfig& audio_track_config = audio_track_config_pair->second;
+  if (audio_track_config_pair == track_configs.end()) {
+    return DistributeBitratesEvenly(track_configs, available_bitrate);
+  } else {
+    RTC_DCHECK(sufficient_audio_bitrate_ >= audio_track_config.min_bitrate_bps);
+    uint32_t sum_min_bitrates = 0;
+    for (const auto& track_config : track_configs) {
+      sum_min_bitrates += track_config.second.min_bitrate_bps;
+    }
+    if (available_bitrate <= sum_min_bitrates) {
+      return SetAllBitratesToMinimum(track_configs);
+    } else {
+      if (available_bitrate <= sum_min_bitrates + sufficient_audio_bitrate_ -
+                                   audio_track_config.min_bitrate_bps) {
+        TrackAllocations track_allocations =
+            SetAllBitratesToMinimum(track_configs);
+        track_allocations[audio_track_id_] +=
+            available_bitrate - sum_min_bitrates;
+        return track_allocations;
+      } else {
+        TrackConfig sufficient_audio_config(audio_track_config);
+        sufficient_audio_config.min_bitrate_bps = sufficient_audio_bitrate_;
+        TrackConfigs sufficient_track_configs(track_configs);
+        sufficient_track_configs[audio_track_id_] = sufficient_audio_config;
+        return DistributeBitratesEvenly(sufficient_track_configs,
+                                        available_bitrate);
+      }
+    }
+  }
+}
+
+}  // namespace rtc