Patent ID: 7680185

Claim:
In a computing device that implements a video decoder, a method comprising: at the computing device that implements the video decoder, receiving from a bit stream plural syntax elements for a current frame, the plural syntax elements including: (a) a frame coding mode syntax element that indicates the current frame is interlaced and organized for decoding as separate first and second fields, the first field having a first field picture type and the second field having a second field picture type, and (b) a field picture types syntax element that jointly indicates the first and second field picture types, each of the first and second field picture types being bi-directionally predicted, wherein bit stream syntax for the field picture types syntax element allows the first and second field picture types to be different field picture types; at the computing device that implements the video decoder, receiving from the bit stream plural field-layer syntax elements for the first field in the current interlaced frame, the first field being partitioned into plural first field macroblocks; with the computing device that implements the video decoder, decoding the first bi-directionally predicted field in the current interlaced frame based at least in part on plural reference fields for the first field, including decoding the plural first field macroblocks; at the computing device that implements the video decoder, receiving from the bit stream plural field-layer syntax elements for the second field in the current interlaced frame, the second field being partitioned into plural second field macroblocks; and with the computing device that implements the video decoder, decoding the second bi-directionally predicted field in the current interlaced frame based at least in part on plural reference fields for the second field, including decoding the plural second field macroblocks, wherein the first field in the current interlaced frame is one of the plural reference fields for the second field in the current interlaced frame.