tcN: fakesrc-fakesink
tcP: fakesrc ! fakesink
tcS: A, fakesrc0, handoff 
tcS: B, fakesink0, handoff
tcI: 2
tcT: 2000
tcR: A,1,B,1,A,1,B,1


tcN: fakesrc-identity-fakesink
tcP: fakesrc ! identity ! fakesink
tcS: A, fakesrc0, handoff 
tcS: B, identity, handoff 
tcS: C, fakesink0, handoff
tcI: 2
tcT: 2000
tcR: A,1,B,1,C,1,A,1,B,1,C,1