Patent ID: 8036264

Claim:
A method of decoding a video frame in a video decoding system comprising a primary memory and a secondary memory, said method comprising: establishing pixel[x−1, y−1] in said primary memory; retaining pixel[x−1, y−1] in said primary memory until pixel[x, y] has been established; and freeing up space in said primary memory by expunging pixel[x, y] from said primary memory before pixel[x+3, y+3] is expunged from said primary memory, wherein x and y are positive multiples of four, pixel[x−1, y−1], pixel[x, y−1], pixel[x+1, y−1], pixel[x+2, y−1], pixel[x−1, y], pixel[x−1, y+1], pixel[x−1, y+2]are retained in said primary memory until pixel[x, y], pixel[x+1, y], pixel[x+2, y], pixel[x+3, y], pixel[x, y+1], pixel[x+1, y+1], pixel[x+2, y+1], pixel[x+3, y+1], pixel[x, y+2], pixel[x+1, y+2], pixel[x+2, y+2], pixel[x+3, y+2], pixel[x, y+3], pixel[x+1, y+3], pixel[x+2, y+3], and pixel[x+3, y+3] are established, pixel[x+3, y−1], pixel[x+3, y], pixel[x+3, y+1], and pixel[x+3, y+2] are retained in said primary memory until pixel[x+4, y], pixel[x+4, y+1], pixel[x+4, y+2], and pixel[x+4, y+3] are established, pixel[x−1, y+3], pixel[x, y+3], pixel[x+1, y+3], and pixel[x+2, y+3] are retained in said primary memory until pixel[x, y+4], pixel[x+1, y+4], pixel[x+2, y+4], and pixel[x+3, y+4] are established, pixel[x+3, y+3] is retained until pixel[x+4,y+4] is established, and pixel[x, y], pixel[x+1, y], pixel[x+2, y], pixel[x, y+1], pixel[x+1, y+1], pixel[x+2, y+1], pixel[x, y+2], pixel[x+1, y+2], and pixel[x+2, y+2] are expunged from said primary memory before pixel[x+3, y], pixel[x+3, y+1], pixel[x+3, y+2], pixel[x, y+3], pixel[x+1, y+3], pixel[x+2, y+3], and pixel[x+3, y+3] are expunged from said primary memory and before pixel[x+4, y], pixel [x+4, y+1], pixel[x+4, y+2], pixel[x+4, y+3], pixel[x, y+4], pixel[x+1, y+4], pixel[x+2, y+4], pixel[x+3, y+4], and pixel[x+4, y+4] are established.