| Abstract | We present an MPEG-2 to H.263 transcoder that accepts an interlaced MPEG-2 bitstream as the input and producesa lower-bitrate progressive H.263 bitstream as the output. As both DVD and digital television may use MPEG-2
interlaced sequences, a potential application of such a transcoder is the transmission of a digital television signal over
a wireless medium. Another application is transcoding interlaced DVD content for use on lower-resolution thin clients
with progressive displays. The proposed algorithm exploits the properties of the MPEG-2 and H.263 compression
standards to perform interlaced to progressive ( eld to frame) conversion with spatial downsampling and frame-rate
reduction in a CPU and memory e cient manner, while additionally minimizing picture quality degradation as
measured by PSNR. This is the rst algorithm to our knowledge that e ectively uses both spatial and temporal
downsampling in an MPEG-2 to H.263 eld to frame transcoder in order to achieve substantial bitrate reduction.
This paper discusses recoding experiments used to determine appropriate source and target coding parameters for
the transcoder, provides a detailed description of the transcoding algorithm, and describes the performance of a
software implementation of the transcoder.
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