Patent ID: 8406300

Claim:
In a device that implements a video decoder, the device including a processor and memory, a method for use in decoding video data within a sequence of video frames, the method comprising: with the device that implements the video decoder, decoding portions of a predictive (P) frame by motion compensation relative to a reference frame using encoded motion vector information associated with the respective portions of the P frame; and with the device that implements the video decoder, decoding first and second direct mode portions of a bidirectionally predictive (B) frame without using motion vector information encoded in a bit stream for the first and second direct mode portions but according to mode identifying data in the bit stream, wherein the mode identifying data indicates whether motion vector information for each of the respective first and second direct mode portions of the B frame is directly derived (a) using the motion vector information associated with the respective portions of the P frame or (b) according to spatial motion vector prediction with motion vector information for other portions in the B frame, including: for any of the first and second direct mode portions of the B frame for which motion vector information is directly derived using the motion vector information associated with the respective portions of the P frame, defining the direct mode portion to include video data predictively correlated to the reference frame based on the motion vector information derived using the motion vector information associated with one of the respective portions of the P frame; and for any of the first and second direct mode portions of the B frame for which motion vector information is directly derived according to spatial motion vector prediction, defining the direct mode portion to include video data predictively correlated to the reference frame based on the motion vector information determined according to spatial motion vector prediction.