Extract common simulcast logic from VP8 wrapper and simulcast adapter

webrtc/modules/video_coding/utility/simulcast_state.h

Index: webrtc/modules/video_coding/utility/simulcast_state.h
diff --git a/webrtc/modules/video_coding/utility/simulcast_state.h b/webrtc/modules/video_coding/utility/simulcast_state.h
new file mode 100644
index 0000000000000000000000000000000000000000..5a9e6f22a50e54f1c38263a5b2e96115a9a10fea
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+++ b/webrtc/modules/video_coding/utility/simulcast_state.h
@@ -0,0 +1,72 @@
+/*
+ *  Copyright (c) 2016 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.
+ *
+ */
+
+#ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_SIMULCAST_STATE_H_
+#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_SIMULCAST_STATE_H_
+
+#include <vector>
+
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/common_types.h"
+
+namespace webrtc {
+
+class SimulcastState {
+ public:
+  explicit SimulcastState(const VideoCodec& codec);
+  virtual ~SimulcastState();
+
+  int AllocateBitrate(int target_bitrate_kbps);

[pbos-webrtc, 2016/04/29 21:23:27]

Can we make all of these _bps instead and move in that direction?

+  void RequestKeyFrame(uint8_t idx);

[pbos-webrtc, 2016/04/29 21:23:27]

Do we ever actually use the index here? Seems to me like all implementations
check if any are set and then send keyframes for all layers.

+  bool GetAndResetKeyFrameRequest(uint8_t idx);
+  void SetSending(uint8_t idx, bool sending);
+
+  std::vector<int> GetStreamRates() const;
+  int SumMaxBitrate() const;
+  int SumTargetBitrate() const;
+  int SumAllocatedBitrate() const;
+  size_t NumStreams() const;
+  size_t NumSendingStreams() const;
+  bool AnyKeyFrameRequested() const;
+  bool IsSending(uint8_t idx) const;
+  int AllocatedRate(uint8_t idx) const;
+
+  struct Stream {
+    Stream(uint8_t idx, VideoCodec* codec, int start_bitrate);
+    VideoCodec AsCodec() const;
+
+    uint8_t idx;
+    SimulcastStream config;
+    int start_bitrate;
+    VideoCodec* parent_codec;
+    bool sending;
+    bool keyframe_request;
+    int allocated_rate_kbps;

[pbos-webrtc, 2016/04/29 21:23:27]

including here

+  };
+
+  std::vector<Stream>::const_iterator begin() const { return streams_.begin(); }

[pbos-webrtc, 2016/04/29 21:23:27]

Replace with const std::vector<Stream>& streams() const { return streams; } so
you use it as for(stream : state->streams()), this is closer to operator
overloading which is disallowed

+  std::vector<Stream>::const_iterator end() const { return streams_.end(); }
+
+ private:
+  int IncreaseBitrateAllocation(Stream* stream, int bitrate_kbps_delta);
+
+  VideoCodec codec_;
+  int sum_max_bitrate_;
+  int sum_target_bitrate_;
+  int sum_allocated_bitrate_;
+  std::vector<Stream> streams_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(SimulcastState);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_SIMULCAST_STATE_H_