Patent ID: 7426308

Claim:
A method of decoding a field-coded macroblock comprising one or more intra-coded blocks, the method comprising: finding a DC differential for a current intra-coded block in the macroblock; selecting a DC predictor from among plural candidate blocks according to a set of DC predictor selection rules, wherein the plural candidate blocks include a top block above the current block, a left block left of the current block, and a top-left block above and to the left of the current block, and wherein the set of DC predictor selection rules indicates the selected DC predictor as follows: if the top-left block, the left block, and the top block are intra-coded, the selected DC predictor depends on respective DC values of the top-left block, the left block, and the top block; if the top-left block is not intra-coded but the left block and the top block are intra-coded, the selected DC predictor depends on the respective DC values of the top block and the left block; if the left block is not intra-coded but the top block is intra-coded, the selected DC predictor is the DC value of the top block; if the top block is not intra-coded but the left block is intra-coded, the selected DC predictor is the DC value of the left block; if the left block is not intra-coded and the top block is not intra-coded, DC prediction is skipped for the current block; obtaining a DC value for the current block, wherein the obtaining comprises; if DC prediction is skipped for the current block, using the DC differential as the DC value for the current block; and if DC prediction is used for the current block, adding the selected DC predictor to the DC differential; and using the DC value in reconstruction of the current block.