1 files changed, 152 insertions, 0 deletions
diff --git a/third_party/libwebrtc/webrtc/rtc_base/bitrateallocationstrategy.cc b/third_party/libwebrtc/webrtc/rtc_base/bitrateallocationstrategy.cc
new file mode 100644
index 0000000000..d2a06cd9ef
--- /dev/null
+++ b/third_party/libwebrtc/webrtc/rtc_base/bitrateallocationstrategy.cc
@@ -0,0 +1,152 @@
+/*
+ *  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 "rtc_base/bitrateallocationstrategy.h"
+#include <algorithm>
+#include <utility>
+
+namespace rtc {
+
+// The purpose of this is to allow video streams to use extra bandwidth for FEC.
+// TODO(bugs.webrtc.org/8541): May be worth to refactor to keep this logic in
+// video send stream. Similar logic is implemented in BitrateAllocator.
+
+const int kTransmissionMaxBitrateMultiplier = 2;
+
+std::vector<uint32_t> BitrateAllocationStrategy::SetAllBitratesToMinimum(
+    const ArrayView<const TrackConfig*> track_configs) {
+  std::vector<uint32_t> track_allocations;
+  for (const auto* track_config : track_configs) {
+    track_allocations.push_back(track_config->min_bitrate_bps);
+  }
+  return track_allocations;
+}
+
+std::vector<uint32_t> BitrateAllocationStrategy::DistributeBitratesEvenly(
+    const ArrayView<const TrackConfig*> track_configs,
+    uint32_t available_bitrate) {
+  std::vector<uint32_t> 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) {
+    auto track_allocations_it = track_allocations.begin();
+    for (const auto* track_config : track_configs) {
+      *track_allocations_it++ = track_config->max_bitrate_bps;
+    }
+    return track_allocations;
+  } else {
+    // If sum_min_bitrates < available_bitrate < sum_max_bitrates allocate
+    // bitrates evenly up to max_bitrate_bps starting from the track with the
+    // lowest max_bitrate_bps. Remainder of available bitrate split evenly among
+    // remaining tracks.
+    std::multimap<uint32_t, size_t> max_bitrate_sorted_configs;
+    for (const TrackConfig** track_configs_it = track_configs.begin();
+         track_configs_it != track_configs.end(); ++track_configs_it) {
+      max_bitrate_sorted_configs.insert(
+          std::make_pair((*track_configs_it)->max_bitrate_bps,
+                         track_configs_it - track_configs.begin()));
+    }
+    uint32_t total_available_increase = available_bitrate - sum_min_bitrates;
+    int processed_configs = 0;
+    for (const auto& track_config_pair : max_bitrate_sorted_configs) {
+      uint32_t available_increase =
+          total_available_increase /
+          (static_cast<uint32_t>(track_configs.size() - processed_configs));
+      uint32_t consumed_increase =
+          std::min(track_configs[track_config_pair.second]->max_bitrate_bps -
+                       track_configs[track_config_pair.second]->min_bitrate_bps,
+                   available_increase);
+      track_allocations[track_config_pair.second] += 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) {}
+
+std::vector<uint32_t> AudioPriorityBitrateAllocationStrategy::AllocateBitrates(
+    uint32_t available_bitrate,
+    const ArrayView<const TrackConfig*> track_configs) {
+  const TrackConfig* audio_track_config = NULL;
+  size_t audio_config_index = 0;
+  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 (track_config->track_id == audio_track_id_) {
+      audio_track_config = track_config;
+      audio_config_index = &track_config - &track_configs[0];
+    }
+  }
+  if (sum_max_bitrates < available_bitrate) {
+    // Allow non audio streams to go above max upto
+    // kTransmissionMaxBitrateMultiplier * max_bitrate_bps
+    size_t track_configs_size = track_configs.size();
+    std::vector<TrackConfig> increased_track_configs(track_configs_size);
+    std::vector<const TrackConfig*> increased_track_configs_ptr(
+        track_configs_size);
+    for (unsigned long i = 0; i < track_configs_size; i++) {
+      increased_track_configs[i] = (*track_configs[i]);
+      increased_track_configs_ptr[i] = &increased_track_configs[i];
+      if (track_configs[i]->track_id != audio_track_id_) {
+        increased_track_configs[i].max_bitrate_bps =
+            track_configs[i]->max_bitrate_bps *
+            kTransmissionMaxBitrateMultiplier;
+      }
+    }
+    return DistributeBitratesEvenly(increased_track_configs_ptr,
+                                    available_bitrate);
+  }
+  if (audio_track_config == nullptr) {
+    return DistributeBitratesEvenly(track_configs, available_bitrate);
+  }
+  auto safe_sufficient_audio_bitrate = std::min(
+      std::max(audio_track_config->min_bitrate_bps, sufficient_audio_bitrate_),
+      audio_track_config->max_bitrate_bps);
+  if (available_bitrate <= sum_min_bitrates) {
+    return SetAllBitratesToMinimum(track_configs);
+  } else {
+    if (available_bitrate <= sum_min_bitrates + safe_sufficient_audio_bitrate -
+                                 audio_track_config->min_bitrate_bps) {
+      std::vector<uint32_t> track_allocations =
+          SetAllBitratesToMinimum(track_configs);
+      track_allocations[audio_config_index] +=
+          available_bitrate - sum_min_bitrates;
+      return track_allocations;
+    } else {
+      // Setting audio track minimum to safe_sufficient_audio_bitrate will
+      // allow using DistributeBitratesEvenly to allocate at least sufficient
+      // bitrate for audio and the rest evenly.
+      TrackConfig sufficient_track_config(*track_configs[audio_config_index]);
+      sufficient_track_config.min_bitrate_bps = safe_sufficient_audio_bitrate;
+      track_configs[audio_config_index] = &sufficient_track_config;
+      std::vector<uint32_t> track_allocations =
+          DistributeBitratesEvenly(track_configs, available_bitrate);
+      return track_allocations;
+    }
+  }
+}
+
+}  // namespace rtc