Detection of resynchronization markers when decoding an MPEG-4 bitstream

摘要

A method for detecting a resynchronization marker in an encoded MPEG-4 video bitstream is provided that includes computing a first candidate resynchronization marker length based on a first version of MPEG-4 Visual and the type of a video object plane (VOP) in the video bitstream, computing a second candidate resynchronization marker length based on a second version of MPEG-4 Visual and the type of the VOP, checking the video bitstream for a first valid resynchronization marker bit sequence using the first candidate resynchronization marker length, checking the video bitstream for a second valid resynchronization marker bit sequence using the second candidate resynchronization marker length, and detecting the resynchronization marker when a valid sequence of stuffing bits is present in the video bitstream after the macroblock boundary and either the first valid resynchronization marker bit sequence or the second valid resynchronization marker bit sequence is found in the video bitstream.

主权项

1. A method of detecting a resynchronization marker in an encoded MPEG-4 video bitstream, the method comprising:
at a macroblock boundary between first and second video packets in a video object plane (VOP) in the video bitstream, checking the video bitstream for a valid sequence of stuffing bits, wherein the VOP is a bi-directionally coded type of VOP; based on the VOP being the bi-directionally coded type of VOP, computing a first candidate resynchronization marker length for the second video packet based on a first version of MPEG-4 Visual; based on the VOP being the bi-directionally coded type of VOP, computing a second candidate resynchronization marker length for the second video packet based on a second version of MPEG-4 Visual; in the second video packet, checking the video bitstream for a first valid resynchronization marker bit sequence having the first candidate resynchronization marker length; in the second video packet, checking the video bitstream for a second valid resynchronization marker bit sequence having the second candidate resynchronization marker length; and without an indication of which of the first and second versions of MPEG-4 Visual was used for encoding the video bitstream, detecting the resynchronization marker in the second video packet, in response to detecting: the valid sequence of stuffing bits in the video bitstream; and one of the first and second valid resynchronization marker bit sequences in the second video packet.