Scalable MPEG-2 video decoder with selective motion compensation

A method of decoding contiguous B pictures by a motion compensation system, comprising the steps of:

• decoding a first B picture using a predefined processing operation;
• calculating an average motion vector magnitude for the first B picture;
• and
• replacing a next contiguous B picture with the first B picture if the average motion vector magnitude is less than or equal to a predetermined threshold.

A program product stored on a recordable medium for processing B pictures in a motion compensation system that when executed, comprises:

• a system for comparing a motion vector magnitude of each macroblock in a B picture with a predetermined threshold;
• a system for performing a routine decoding operation on each macroblock in which the motion vector magnitude is greater than the predetermined threshold;
• and
• a system for copying a corresponding macroblock from a reference picture for each macroblock in which the motion vector magnitude is less than or equal to the predetermined threshold.

A decoder system having a motion compensation system, wherein the motion compensation system comprises:

• a system for comparing a motion vector magnitude of each macroblock in a B picture with a predetermined threshold;
• a system for performing a routine decoding operation for each macroblock in which the motion vector magnitude is greater than the predetermined threshold;
• and
• a system for copying a corresponding macroblock from a reference picture for each macroblock in which the motion vector magnitude is less than or equal to the predetermined threshold.