1. A method for determining a prediction mode for performing intra prediction of a plurality of frames in a digital video, said digital video being in H.264 video coding format, the method comprising: determining a 16×16 prediction mode from a first set of plurality of prediction modes for each of an intra 16×16 macroblock of each frame of said plurality of frames in said digital video, wherein said 16×16 prediction mode being determined based on a calculated computational cost, wherein said computational cost being calculated by utilizing a first pre-defined criteria for each of said first set of plurality of prediction modes, wherein said 16×16 prediction mode being a first mode decision; deciding a 4×4 prediction mode from a second set of plurality of prediction modes for each of an intra 4×4 sub-macroblock of said intra 16×16 macroblock of each said corresponding frame of said plurality of frames in said digital video, wherein said 4×4 prediction mode being determined based on a calculated computational cost, wherein said computational cost being calculated by utilizing a second pre-defined criteria for each of said second set of plurality of prediction modes, wherein said 4×4 prediction mode being a second mode decision; comparing computational cost of said first mode decision and said second mode decision; and declaring one of said first mode decision and said second mode decision as a prediction mode for each of said macroblock based on compared computational cost.