Called when any processing is needed from the filter, instead of any
filter_frame and request_frame on pads.
The function must examine inlinks and outlinks and perform a single
step of processing. If there is nothing to do, the function must do
nothing and not return an error. If more steps are or may be
possible, it must use ff_filter_set_ready() to schedule another
activation.
Filter activation function.
Called when any processing is needed from the filter, instead of any filter_frame and request_frame on pads.
The function must examine inlinks and outlinks and perform a single step of processing. If there is nothing to do, the function must do nothing and not return an error. If more steps are or may be possible, it must use ff_filter_set_ready() to schedule another activation.