1. A method of decoding an encoded video bitstream, said method comprising the steps of: receiving said encoded video bitstream comprising frame header information and macroblock information, said frame header information defining a sequence of frames and each frame being composed of macroblocks represented by said macroblock information; parsing said encoded video bitstream using a first parsing unit and a second parsing unit, each parsing unit independently deriving a full set of parsing state information from said encoded video bitstream on which subsequent parsing of said encoded video bitstream at least partially depends and which identifies data dependencies of frames in said encoded video bitstream, and identifying macroblock information for decoding, and said parsing step includes parsing all of said frame header information in both said first parsing unit and in said second parsing unit such that each parsing unit maintains said full set of said parsing state information for said encoded video bitstream; and allocating each frame of macroblock information to one of said first parsing unit and said second parsing unit, wherein said first parsing unit and said second parsing unit each parse said macroblock information, skipping macroblock information allocated to the other parsing unit, the full set parsing state information derived by each parsing unit identifying data dependencies of at least one frame allocated to the other parsing unit.
1. A method of decoding an encoded video bitstream, said method comprising the steps of: receiving said encoded video bitstream comprising frame header information and macroblock information, said frame header information defining a sequence of frames and each frame being composed of macroblocks represented by said macroblock information; parsing said encoded video bitstream using a first parsing unit and a second parsing unit, each parsing unit independently deriving a full set of parsing state information from said encoded video bitstream on which subsequent parsing of said encoded video bitstream at least partially depends and which identifies data dependencies of frames in said encoded video bitstream, and identifying macroblock information for decoding, and said parsing step includes parsing all of said frame header information in both said first parsing unit and in said second parsing unit such that each parsing unit maintains said full set of said parsing state information for said encoded video bitstream; and allocating each frame of macroblock information to one of said first parsing unit and said second parsing unit, wherein said first parsing unit and said second parsing unit each parse said macroblock information, skipping macroblock information allocated to the other parsing unit, the full set parsing state information derived by each parsing unit identifying data dependencies of at least one frame allocated to the other parsing unit. 10. The method of decoding an encoded video bitstream as claimed in claim 1 , wherein in said parsing step said first parsing unit and said second parsing unit resolve data dependencies between macroblocks in a second pass of each frame.