new channel1 broadcast enabled
setup channel1 input ./input.mp3
setup channel1 output #duplicate{dst=mosaic-bridge{id=1},select=video,dst=bridge-out{id=1},select=audio}

new background broadcast enabled
setup background input fake:
set background option fake-file=background.png
setup background output #transcode{sfilter=mosaic,vcodec=mp2v,acodec=mpga,vb=1000,ab=128,scale=1}:bridge-in{delay=100,id-offset=100}:standard{access=file,mux=ts,url=out.ts,sap,name="mosaic"}

control background play
control channel1 play