PrerollNode
status_t PrerollNode(const media_node& node);
err = BMediaRoster::Roster()->PrerollNode(
r->PrerollNode(mConnection.consumer);
r->PrerollNode(mConnection.producer);
status_t err = roster->PrerollNode(fMediaOutput.node);
fRoster->PrerollNode(mixer);
fRoster->PrerollNode(soundcard);
rv = roster->PrerollNode(sourceNode);
rv = roster->PrerollNode(destinationNode);