Refactor how padding is calculated.

webrtc/video/vie_encoder.h

Index: webrtc/video/vie_encoder.h
diff --git a/webrtc/video/vie_encoder.h b/webrtc/video/vie_encoder.h
index 212962348ad7a110c24a3060437fe7c320e1531e..c7246a7c792a91db9255bd4b7865d0920857c905 100644
--- a/webrtc/video/vie_encoder.h
+++ b/webrtc/video/vie_encoder.h
@@ -49,6 +49,23 @@ class VideoEncoder;
 //    the encoded bit stream.
 // 5. Call Start.
 // 6. For each available raw video frame call EncodeVideoFrame.
+
+class VideoEncoderSink : public EncodedImageCallback {
+ public:
+  static const int TimeOutMs = 2000;
+
+  // Triggered if the encoder has not produced a frame for |TimeOutMs|.
+  // The effect of this call is that no padding will be sent for this stream and
+  // thus, this method should thus not be called if padding is needed.
+  // Note that this method should not be called if the encoder is
+  // not supposed to produce data. Ie, the current allowed bitrate is zero.
+  // May be called on an arbitrary thread.
+  virtual void OnEncoderActivityChanged(bool running) = 0;
+
+ protected:
+  virtual ~VideoEncoderSink() {}
+};
+
 class ViEEncoder : public VideoEncoderRateObserver,
                    public EncodedImageCallback,
                    public VCMSendStatisticsCallback {
@@ -59,8 +76,7 @@ class ViEEncoder : public VideoEncoderRateObserver,
              ProcessThread* module_process_thread,
              SendStatisticsProxy* stats_proxy,
              OveruseFrameDetector* overuse_detector,
-             EncodedImageCallback* sink);
-
+             VideoEncoderSink* sink);
   ~ViEEncoder();
 
   vcm::VideoSender* video_sender();
@@ -78,12 +94,19 @@ class ViEEncoder : public VideoEncoderRateObserver,
                                   bool internal_source);
   int32_t DeRegisterExternalEncoder(uint8_t pl_type);
   void SetEncoder(const VideoCodec& video_codec,
-                  int min_transmit_bitrate_bps,
                   size_t max_data_payload_length);
 
   void EncodeVideoFrame(const VideoFrame& video_frame);
   void SendKeyFrame();
 
+  // Checks to see if the encoder has produced anything during the last
+  // VideoEncoderSink::TimeOutMs period and if the state has changed, calls
+  // VideoEncoderSink::OnEncoderActivityChanged.
+  // Must be called periodically.
+  // TODO(perkj): CheckForActivity should be replaced with an internal timer
+  // once ViEncoder owns the encoder thread.
+  void CheckForActivity();
+
   uint32_t LastObservedBitrateBps() const;
   // Loss protection. Must be called before SetEncoder() to have max packet size
   // updated according to protection.
@@ -108,8 +131,6 @@ class ViEEncoder : public VideoEncoderRateObserver,
   virtual void OnReceivedSLI(uint8_t picture_id);
   virtual void OnReceivedRPSI(uint64_t picture_id);
 
-  int GetPaddingNeededBps() const;
-
   void OnBitrateUpdated(uint32_t bitrate_bps,
                         uint8_t fraction_lost,
                         int64_t round_trip_time_ms);
@@ -120,7 +141,7 @@ class ViEEncoder : public VideoEncoderRateObserver,
   void TraceFrameDropEnd() EXCLUSIVE_LOCKS_REQUIRED(data_cs_);
 
   const uint32_t number_of_cores_;
-  EncodedImageCallback* const sink_;
+  VideoEncoderSink* const sink_;
 
   const std::unique_ptr<VideoProcessing> vp_;
   vcm::VideoSender video_sender_;
@@ -135,10 +156,10 @@ class ViEEncoder : public VideoEncoderRateObserver,
   // padding.
   int64_t time_of_last_frame_activity_ms_ GUARDED_BY(data_cs_);
   VideoCodec encoder_config_ GUARDED_BY(data_cs_);
-  int min_transmit_bitrate_bps_ GUARDED_BY(data_cs_);
   uint32_t last_observed_bitrate_bps_ GUARDED_BY(data_cs_);
   bool encoder_paused_ GUARDED_BY(data_cs_);
   bool encoder_paused_and_dropped_frame_ GUARDED_BY(data_cs_);
+  bool reported_timeout_ GUARDED_BY(data_cs_);
 
   ProcessThread* module_process_thread_;