H.264 to MPEG-2 Conversion of Intra Coded Video

This paper addresses the problem of converting intra coded video from H.264 to MPEG-2. Since these two coded formats have fundamental differences in regard to their transform block sizes and intra prediction modes, conversion between them is a challenging task. A fast frequency domain conversion method is proposed to convert the integer transform (IT) coefficients into discrete cosine transform (DCT) coefficients, including support for those intra prediction modes that were found to be suitable for such a conversion. The proposed method achieves faster computation than resorting to pixel domain at the expense of a small distortion. It is also shown that some intra prediction modes are not suitable for transform domain conversion because the computational complexity is much higher than pixel domain conversion.