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..a3226a5fc8f453562eb00186e23f4f75439a54a3
--- /dev/null
+++ b/webrtc/modules/video_coding/utility/simulcast_state.h
@@ -0,0 +1,59 @@
+/*
+ *  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/common_types.h"
+
+namespace webrtc {
+
+class SimulcastState {
+ public:
+  explicit SimulcastState(const VideoCodec& codec);
+  virtual ~SimulcastState();
+
+  int AllocateBitrate(int target_bitrate_bps);
+  void RequestKeyFrame(uint8_t idx);

[stefan-webrtc, 2016/05/06 11:43:20]

Could we split this class in two and have one for rate allocation and another
one for things like key frames etc? Then we could potentially move the
allocation part out from the codecs entirely and put it inside, e.g.,
BitrateAllocator instead, which would then allocate several bitrates for a
simulcast send-stream.

+  bool GetAndResetKeyFrameRequest(uint8_t idx);
+  void SetSending(uint8_t idx, bool sending);
+
+  size_t NumStreams() const;
+  size_t NumSendingStreams() const;
+  bool IsSending(uint8_t idx) const;
+  int AllocatedRate(uint8_t idx) const;
+
+  struct Stream {
+    Stream(uint8_t idx, VideoCodec* codec, int start_bitrate_bps);
+    VideoCodec AsCodec() const;
+
+    uint8_t idx;
+    SimulcastStream config;
+    int start_bitrate;
+    VideoCodec* parent_codec;
+    bool sending;
+    bool keyframe_request;
+    int allocated_rate_bps;
+  };
+  const std::vector<Stream>& Streams() const;
+
+ private:
+  int IncreaseBitrateAllocation(Stream* stream, int bitrate_bps_delta);
+
+  VideoCodec codec_;
+  std::vector<Stream> streams_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_SIMULCAST_STATE_H_