Patent ID: 7092442

Claim:
A method for adaptively encoding a sequence of images, the sequence of images including P-frames and B-frames, comprising: partitioning the P-frames and B-frames into macroblocks, and extracting motion activity from the macroblocks; separating each image of the video into a top-field and a bottom-field; extracting motion activity both from the top-field and from the bottom-field; initializing an MB field counter and an MB frame counter to zero; determining a variance of the top-field and a variance of the bottom-field by Var = ∑ i ⁢ ( P i - E ⁡ ( P i ) ) 2 , where P i denotes a pixel value and E(P i ) denotes a mean value of the corresponding field; determining a ratio of the two variances; and if Var(top-field)/Var(bottom-field )>Threshold 1 , MB 13 field+=1; else if Var(top-field)/Var(bottom-field)<Threshold 2 , MB 13 field+=1; else MB 13 frame+=1.; and encoding each image using either frame encoding or field encoding depending on the motion activity extracted from the top-field and the bottom field.