In this paper, we study the problem of video transcoding from MPEG-2 to WMV format, together with several desired functionalities such as bit rate reduction etc. We propose two architectures (for different typical application scenarios) that are unique in their complexity scalability and adaptive drifting error control, which in return provide a mechanism to achieve desired trade-off between the complexity and the quality. A simple model-based rate control algorithm is also presented. We performed extensive experiments for various design targets such as complexity scalability, performance tradeoff, drifting control effect etc. The proposed transcoding architectures can be straightforwardly applied to the MPEG-2 to MPEG-4 transcoding applications due to the significant overlap between the MPEG-4 and WMV coding technology.