A split architecture for encoding a video stream. A source encoder may encode a video content stream to obtain an encoded bitstream and a side information stream. The side information stream includes information characterizing rate and/or distortion estimation functions per block of the video content stream. Also, a different set of estimation functions may be included per coding mode. The encoded bitstream and side information stream may be received by a video transcoder, which transcodes the encoded bitstream to a client-requested picture resolution, according to a client-requested video format and bit rate. The side information stream allows the transcoder to efficient and compactly perform rate control for its output bitstream, which is transmitted to the client device. This split architecture may be especially useful to operators of content delivery networks.