Implementing auto pausing of video streams.

webrtc/call/bitrate_allocator.h

 /*
  *  Copyright (c) 2015 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.
  */
 
@@ skipping 24 matching lines @@
 };
 
 // Usage: this class will register multiple RtcpBitrateObserver's one at each
 // RTCP module. It will aggregate the results and run one bandwidth estimation
 // and push the result to the encoders via BitrateAllocatorObserver(s).
 class BitrateAllocator {
  public:
   BitrateAllocator();
 
   // Allocate target_bitrate across the registered BitrateAllocatorObservers.
-  // Returns actual bitrate allocated (might be higher than target_bitrate if
-  // for instance EnforceMinBitrate() is enabled.
-  uint32_t OnNetworkChanged(uint32_t target_bitrate,
+  // Returns actual bitrate allocated, which might be higher than target_bitrate
+  // if for instance EnforceMinBitrate() is enabled.
+  uint32_t OnNetworkChanged(uint32_t target_bitrate_bps,
                             uint8_t fraction_loss,
                             int64_t rtt);
 
   // Set the start and max send bitrate used by the bandwidth management.
   //
   // |observer| updates bitrates if already in use.
   // |min_bitrate_bps| = 0 equals no min bitrate.
   // |max_bitrate_bps| = 0 equals no max bitrate.
   // |enforce_min_bitrate| = 'true' will allocate at least |min_bitrate_bps| for
   //    this observer, even if the BWE is too low, 'false' will allocate 0 to
   //    the observer if BWE doesn't allow |min_bitrate_bps|.
   // Returns initial bitrate allocated for |observer|.
   // Note that |observer|->OnBitrateUpdated() will be called within the scope of
   // this method with the current rtt, fraction_loss and available bitrate and
   // that the bitrate in OnBitrateUpdated will be zero if the |observer| is
   // currently not allowed to send data.
   int AddObserver(BitrateAllocatorObserver* observer,
                   uint32_t min_bitrate_bps,
                   uint32_t max_bitrate_bps,
                   bool enforce_min_bitrate);
 
+  // Removes a previously added observer, but will not trigger a new bitrate
+  // allocation.
   void RemoveObserver(BitrateAllocatorObserver* observer);
 
  private:
+  // Note: All bitrates for member variables and methods are in bps.
   struct ObserverConfig {
     ObserverConfig(BitrateAllocatorObserver* observer,
                    uint32_t min_bitrate_bps,
                    uint32_t max_bitrate_bps,
                    bool enforce_min_bitrate)
         : observer(observer),
           min_bitrate_bps(min_bitrate_bps),
           max_bitrate_bps(max_bitrate_bps),
           enforce_min_bitrate(enforce_min_bitrate) {}
     BitrateAllocatorObserver* const observer;
     uint32_t min_bitrate_bps;
     uint32_t max_bitrate_bps;
     bool enforce_min_bitrate;
   };
 
-  // This method controls the behavior when the available bitrate is lower than
-  // the minimum bitrate, or the sum of minimum bitrates.
-  // When true, the bitrate will never be set lower than the minimum bitrate(s).
-  // When false, the bitrate observers will be allocated rates up to their
-  // respective minimum bitrate, satisfying one observer after the other.
-  void EnforceMinBitrate(bool enforce_min_bitrate)
-      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
-
   typedef std::list<ObserverConfig> ObserverConfigList;
   ObserverConfigList::iterator FindObserverConfig(
       const BitrateAllocatorObserver* observer)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
 
   typedef std::multimap<uint32_t, const ObserverConfig*> ObserverSortingMap;
   typedef std::map<BitrateAllocatorObserver*, int> ObserverAllocation;
 
   ObserverAllocation AllocateBitrates(uint32_t bitrate)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
-  ObserverAllocation NormalRateAllocation(uint32_t bitrate,
-                                          uint32_t sum_min_bitrates)
-      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
 
   ObserverAllocation ZeroRateAllocation() EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
   ObserverAllocation LowRateAllocation(uint32_t bitrate)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+  ObserverAllocation NormalRateAllocation(uint32_t bitrate,
+                                          uint32_t sum_min_bitrates)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+  ObserverAllocation MaxRateAllocation(uint32_t bitrate,
+                                       uint32_t sum_max_bitrates)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+
+  uint32_t LastAllocatedBitrate(const ObserverConfig& observer_config)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+  // The minimum bitrate required by this observer, including enable-hysteresis
+  // if the observer is in a paused state.
+  uint32_t MinBitrateWithHysteresis(const ObserverConfig& observer_config)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+  // Splits |bitrate| evenly to observers already in |allocation|.
+  // |include_zero_allocations| decides if zero allocations should be part of
+  // the distribution or not. The allowed max bitrate is |max_multiplier| x
+  // observer max bitrate.
+  void DistributeBitrateEvenly(uint32_t bitrate,
+                               bool include_zero_allocations,
+                               int max_multiplier,
+                               ObserverAllocation* allocation)
+          EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+  bool EnoughBitrateForAllObservers(uint32_t bitrate, uint32_t sum_min_bitrates)
+      EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
+
 
   rtc::CriticalSection crit_sect_;
   // Stored in a list to keep track of the insertion order.
   ObserverConfigList bitrate_observer_configs_ GUARDED_BY(crit_sect_);
-  bool enforce_min_bitrate_ GUARDED_BY(crit_sect_);
   uint32_t last_bitrate_bps_ GUARDED_BY(crit_sect_);
   uint32_t last_non_zero_bitrate_bps_ GUARDED_BY(crit_sect_);
   uint8_t last_fraction_loss_ GUARDED_BY(crit_sect_);
   int64_t last_rtt_ GUARDED_BY(crit_sect_);
+  ObserverAllocation last_allocation_ GUARDED_BY(crit_sect_);
 };
 }  // namespace webrtc
 #endif  // WEBRTC_CALL_BITRATE_ALLOCATOR_H_