Intra-macroblock DC and AC coefficient prediction for interlaced digital video

A method for decoding differentially encoded spatial transform coefficients of a current, INTRA coded block in a digital video image which is transmitted in a digital bitstream to recover corresponding full AC spatial transform coefficients of said current block, comprising the steps of:

• recovering said digital bitstream;
• said digital bitstream comprising data from an adjacent left-hand block, an adjacent top block, and a top, left block which is adjacent to said left-hand block and said top block;
• said left-hand block, top block, and top, left block each having a DC spatial transform coefficient and a plurality of AC spatial transform coefficients;
• each of said blocks being coded in a coding mode according to one of a frame mode, a reordered field mode, and a non-reordered field mode;
• selecting AC spatial transform coefficients from one of said left-hand block and said top block;
• and
• summing said selected AC spatial transform coefficients with said corresponding differentially encoded AC spatial transform coefficients of said current block to recover said full AC spatial transform coefficients of said current block;
• said selecting step being responsive to the coding mode of said current block and said top block.

An apparatus for coding spatial transform coefficients of a current, INTRA coded block in a digital video image, comprising:

• means for identifying an adjacent left-hand block, an adjacent top block, and a top, left block which is adjacent to said left-hand block and said top block;
• said left-hand block, top block, and top, left block each having a DC spatial transform coefficient and a plurality of AC spatial transform coefficients;
• each of said blocks being coded in a coding mode according to one of a frame mode, a reordered field mode, and a non-reordered field mode;
• and
• means for selecting AC spatial transform coefficients from one of said left-hand block and said top block for use in differentially encoding respective AC spatial transform coefficients of said current block;
• said means for selecting being responsive to the coding mode of said current block and said top block.

An apparatus for decoding differentially encoded spatial transform coefficients of a current, INTRA coded block in a digital video image which is transmitted in a digital bitstream to recover corresponding full AC spatial transform coefficients of said current block, comprising:

• means for recovering said digital bitstream;
• said digital bitstream comprising data from an adjacent left-hand block, an adjacent top block, and a top, left block which is adjacent to said left-hand block and said top block;
• said left-hand block, top block, and top, left block each having a DC spatial transform coefficient and a plurality of AC spatial transform coefficients;
• each of said blocks being coded in a coding mode according to one of a frame mode, a reordered field mode, and a non-reordered field mode;
• first means for selecting AC spatial transform coefficients from one of said left-hand block and said top block;
• and
• means for summing said selected AC spatial transform coefficients with said corresponding differentially encoded AC spatial transform coefficients of said current block to recover said full AC spatial transform coefficients of said current block;
• said first means for selecting being responsive to the coding mode of said current block and said top block.