函数 sws_frame_end 

pub unsafe extern "C" fn sws_frame_end(c: *mut SwsContext)

Finish the scaling process for a pair of source/destination frames previously submitted with sws_frame_start(). Must be called after all sws_send_slice() and sws_receive_slice() calls are done, before any new sws_frame_start() calls.

@param c The scaling context