Rate Control Algorithm for MPEG-2 to H.264/AVC Transcoding

There is strong need for research in transcoding technologies to enable smooth displacement from MPEG-2 to H.264/AVC since H.264/AVC has been standardized as international standard. In this paper, a novel rate control algorithm for MPEG-2 to H.264/AVC transcoding, which adopting a new block activity measurement, is proposed. Specifically, the standard deviation of the residual error is introduced into the quadratic rate distortion (R-D) model adopted in JVT-G012 instead of the mean of absolute difference (MAD) to measure macroblock (MB) complexity. Meanwhile, based on the fact that the mean square of AC coefficients in an 8×8 DCT block is equal to the variance of an 8×8 block before DCT, we derive a close-form formulation to calculate the variance of a residual MB using the DCT coefficients rather the pixel values. Obviously, this rate control method can be used for MPEG-2 to H.264/AVC transcoder in both pixel domain and transform domain. Experiments show that our proposed algorithm can meet the target bit-rate accurately and achieves a better performance than the JVT-G012.