--- You should return two objects; the chain itself, and then a
--- function (taking no parameters) that is run just before rendering.
--- The function needs to call connect_signal on any inputs, so that
--- it gets updated video data for the given frame. (You are allowed
--- to switch which input your input is getting from between frames,
--- but not calling connect_signal results in undefined behavior.)
--- If you want to change any parameters in the chain, this is also
--- the right place.
---
--- NOTE: The chain returned must be finalized with the Y'CbCr flag
--- if and only if num==0.
-function get_chain(num, t, width, height, signals)
- local chain, signal_num
+-- You should return the scene to use, after having set any parameters you
+-- want to set (through set_int() etc.). The parameters will be snapshot
+-- at return time and used during rendering.
+function get_scene(num, t, width, height, signals)
+ local signal_num