[H264][Simulcast] Implement the simulcast logic for h264 encoder

webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.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 43 matching lines @@
   int32_t SetPeriodicKeyFrames(bool enable) override;
   void OnDroppedFrame() override;
 
  private:
   bool IsInitialized() const;
 
   // Reports statistics with histograms.
   void ReportInit();
   void ReportError();
 
-  ISVCEncoder* openh264_encoder_;
+  // Set the stream state for stream |stream_idx|.
+  void SetStreamState(bool send_stream, int stream_idx);
+
+  // Scale input_frame to the dimensions of output_frame
+  void Scale(const VideoFrame& input_frame, VideoFrame* output_frame);
+
+  inline uint32_t CalculateYStrideSize(uint32_t frame_width,
+                                       uint32_t frame_height) {
+    return frame_width;
+  }
+
+  inline uint32_t CalculateUVStrideSize(uint32_t frame_width,
+                                        uint32_t frame_height) {
+    return (frame_width + 1) / 2;
+  }
+
+  std::vector<ISVCEncoder*> encoders_;
   VideoCodec codec_settings_;
 
-  EncodedImage encoded_image_;
-  std::unique_ptr<uint8_t[]> encoded_image_buffer_;
   EncodedImageCallback* encoded_image_callback_;
-
   bool has_reported_init_;
   bool has_reported_error_;
+
+  std::vector<VideoFrame> scaled_input_frames_;
+  std::vector<EncodedImage> encoded_images_;
+  std::vector<std::unique_ptr<uint8_t[]>> encoded_image_buffers_;
+  std::vector<bool> send_streams_;
+  std::vector<bool> key_frame_request_;

[sprang_webrtc, 2017/03/29 08:44:21]

These vectors and encoders_ have to match index wise, right? If so, can we put
them in a struct and have a single vector instead?

 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_VIDEO_CODING_CODECS_H264_H264_ENCODER_IMPL_H_