remove try from ffplay process

ffplayout.py

@@ -678,16 +678,11 @@ def main():
         try:
             if _playout.preview:
                 # preview playout to player
-                try:
                 playout = Popen(
                     ['ffplay', '-i', 'pipe:0'],
                     stdin=mbuffer.stdout,
                     bufsize=0
                     )
-                except OSError as e:
-                    logger.error(e)
-                    mbuffer.terminate()
-                    sys.exit(1)
             else:
                 # playout to rtmp
                 if _pre_comp.copy: