Detection of resynchronization markers when decoding an MPEG-4 bitstream

A video decoder for decoding an encoded MPEG-4 video bitstream, wherein the decoding comprises detecting a resynchronization marker in the encoded MPEG-4 video bitstream, and wherein the detecting comprises:

• 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.

A system, comprising:

• at least one processor;
• and
• at least one memory storing instructions executable by the processor for detecting a resynchronization marker in an encoded MPEG-4 video bitstream, wherein the detecting comprises:
• 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.