Patent ID: 8594197

Claim:
A method for compressing a video stream, the method comprising: receiving a differentially encoded video stream comprising standard encoded video frames, wherein at least a portion of the standard encoded video frames are standard encoded I-frames; compressing at least a portion of the standard encoded I-frames using relative compression to obtain compressed encoded I-frames; and replacing the standard encoded I-frames in the video stream with the compressed encoded I-frames to obtain a compressed encoded video stream, wherein compressing comprises: decoding the standard encoded I-frames using variable length decoding (VLD) to obtain decoded I-frames; dividing the decoded I-frames into groups, each group having a respective reference I-frame; for each block of each decoded I-frame that is not a reference I-frame: subtracting the block of the decoded I-frame from at least one respective reference block to obtain at least one subtracted block; encoding the at least one subtracted block using variable length coding (VLC) obtain at least one encoded subtracted block; comparing the size of the at least one encoded subtracted block with the size of the respective block of the respective standard encoded I-frame; and if one of the encoded subtracted block is smaller than the respective block of the respective standard encoded I-frame, then replacing the respective block of the standard encoded I-frame with the smallest respective encoded subtracted block; and adding data to the I-frame indicating for each block of the I-frame whether the block is an encoded subtracted block, and an identification of said encoded subtracted block.