GF_Err gf_filter_set_process_event_ckb(GF_Filter *filter, Bool (*process_event_cbk)(GF_Filter *filter, const GF_FilterEvent *evt) )
{
	if (! (filter->freg->flags & GF_FS_REG_CUSTOM)) {
		GF_LOG(GF_LOG_ERROR, GF_LOG_FILTER, ("Attempt to assign filter callback on non custom filter %s\n", filter->freg->name));
		return GF_BAD_PARAM;
	}
	((GF_FilterRegister *) filter->freg)->process_event = process_event_cbk;
	return GF_OK;
}
GF_Err gf_filter_set_process_event_ckb(GF_Filter *filter, Bool (*process_event_cbk)(GF_Filter *filter, const GF_FilterEvent *evt) )
{
	if (! (filter->freg->flags & GF_FS_REG_CUSTOM)) {
		GF_LOG(GF_LOG_ERROR, GF_LOG_FILTER, ("Attempt to assign filter callback on non custom filter %s\n", filter->freg->name));
		return GF_BAD_PARAM;
	}
	((GF_FilterRegister *) filter->freg)->process_event = process_event_cbk;
	return GF_OK;
}