BWE allocation strategy

webrtc/rtc_base/bitrateallocationstrategy.cc

+/*
+ *  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->track_id] = track_config->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->min_bitrate_bps;
+    sum_max_bitrates += track_config->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->track_id] = track_config->max_bitrate_bps;
+    }
+    return track_allocations;
+  } else {
+    std::multimap<uint32_t, const 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->max_bitrate_bps, track_config.get()));
+    }
+    uint32_t total_available_increase = (available_bitrate - sum_min_bitrates);
+    int processed_configs = 0;
+    for (const auto& track_config_pair : max_bitrate_sorted_configs) {
+      const 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) {
+  TrackConfig* audio_track_config = NULL;
+  size_t audio_config_index = -1;
+  uint32_t sum_min_bitrates = 0;
+  for (const auto& track_config : track_configs) {
+    sum_min_bitrates += track_config->min_bitrate_bps;
+    if (track_config->track_id == audio_track_id_) {
+      audio_track_config = track_config.get();
+      audio_config_index = &track_config - &track_configs[0];
+    }
+  }
+  if (audio_track_config == NULL) {
+    return DistributeBitratesEvenly(track_configs, available_bitrate);
+  }
+  RTC_DCHECK(sufficient_audio_bitrate_ >= audio_track_config->min_bitrate_bps);
+  for (const auto& track_config : track_configs) {
+    sum_min_bitrates += track_config->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 {
+      uint32_t config_min_bitrate_bps =
+          track_configs[audio_config_index]->min_bitrate_bps;
+      track_configs[audio_config_index]->min_bitrate_bps =
+          sufficient_audio_bitrate_;
+      TrackAllocations track_allocations =
+          DistributeBitratesEvenly(track_configs, available_bitrate);
+      track_configs[audio_config_index]->min_bitrate_bps =
+          config_min_bitrate_bps;
+      return track_allocations;
+    }
+  }
+}
+
+}  // namespace rtc