Sourcetype t = {width : int;height : int;times : float array;duration : float;frame : int -> Rgba_image.t;
} Sourceval sequential :
width:int ->
height:int ->
times:float array ->
duration:float ->
start:(unit -> 's) ->
next:('s -> 's * Rgba_image.t) ->
t Sourceval index_at : t -> float -> int