adjusting timestamps when hot switching the camera

When switching cameras, the encoders must be paused. Otherwise, there will be problems with the DTS on the client,  SRS  server with enabled time_jitter incorrectly corrects video DTS (with enabled ATC  there is no problem)

library/src/main/java/net/ossrs/yasea/SrsPublisher.java

@@ -309,6 +309,11 @@ public class SrsPublisher {
     }
 
     public void switchCameraFace(int id) {
+        
+        if (mEncoder != null && mEncoder.isEnabled()) {
+            mEncoder.pause();
+        }        
+        
         mCameraView.stopCamera();
         mCameraView.setCameraId(id);
         if (id == 0) {
@@ -320,6 +325,11 @@ public class SrsPublisher {
             mCameraView.enableEncoding();
         }
         mCameraView.startCamera();
+        
+        if (mEncoder != null && mEncoder.isEnabled()) {
+            mEncoder.resume();
+        }        
+        
     }
 
     public void setRtmpHandler(RtmpHandler handler) {