OptionalchunkOptionallookaheadhow far ahead of the clock chunks are queued; 2 seconds when omitted, enough to ride out a throttled background timer
Optionalpumpmilliseconds between self-driven pumps; 100 when omitted, 0 to turn the timer off and call update() yourself
Optionalschedulereplaces setTimeout for the pump, so a test drives time by hand
Optionalunschedulecancels what schedule returned; clearTimeout when omitted
seconds of audio per scheduled chunk; 0.5 when omitted