A method for real-time transcoding of MPEG-2 video bit streams is presented that can be applied at different levels of complexity. The proposed method has been developed in the ACTS ATLANTIC project. It is based on the following elements: a) reuse of motion vectors and coding mode decisions carred in the input bit stream, b) modelling of the impairments already present in the input, c) Use of bit rate statistics from the input bit stream. Experimental results confirm that high picture quality can be maintained. Furthermore, the proposed elements and transcoding algorithms are not limited to MPEG-2 and can be extended to a generic transcoding method suitable for the common standards JPEG, H.263, MPEG-1 and MPEG-2 alike.

Paper given at IBC conference, 1997. International Broadcasting Convention.