|unique name for this input/output in the list
|filter context associated to this input/output
|index of the filt_ctx pad to use for linking
|struct AVFilterInOut *
|next input/input in the list, NULL if this is the last
This is mainly useful for avfilter_graph_parse(), since this function may accept a description of a graph with not connected input/output pads. This struct specifies, per each not connected pad contained in the graph, the filter context and the pad index required for establishing a link.