question: public static byte [ ] buildNalUnit ( byte [ ] data , int offset , int length ) { byte [ ] nalUnit = new byte [ length + NAL_START_CODE . length ] ; System . arraycopy ( NAL_START_CODE , 0 , nalUnit , 0 , NAL_START_CODE . length ) ; System . arraycopy ( data , offset , nalUnit , NAL_START_CODE . length , length ) ; return nalUnit ; }
target:  Constructs a NAL unit consisting of the NAL start code followed by the specified data.