Transform domain transcoding from MPEG-2 to H.264 with interpolation error drift compensation
A complete transform domain solution to transcode MPEG-2 to H.264 is proposed. Firstly, we propose an efficient transcoding architecture for intra frames by taking advantage of the fact that the intra prediction of horizontal, vertical, and DC modes can be efficiently obtained in transform domain with very low computational complexity. Then, for the transcoding of inter frames, we analyze two major kinds of drifting error resulting from the mismatch of motion compensation: interpolation error and quantization error. The former is caused by the difference between the interpolation filters adopted in these two standards, thus very unique to the transform domain transcoding from MPEG-2 to H.264. As a major contribution of this paper, the close form of interpolation error is derived from transform domain. Experimental results show that the proposed transform domain transcoding scheme achieves very promising performance in terms of low computational complexity and high transcoded video quality, most importantly its PSNR is very close to the cascaded transcoding architecture with decoding and recoding process in pixel domain.