Minimum-drift digital video downconversion

This paper presents a new technique for decoding a full-resolution video bitstream at low memory cost and displaying the signal at a lower resolution. Existing techniques solve the problem by storing the downconverted blocks into memory instead of the full-resolution blocks. While the memory is reduced, these techniques introduce drift errors because the decoder does not have the same pixels as the encoder in performing motion-compensated prediction. The approach proposed here alleviates the problem by tracking the drift at the decoder. It improves the video quality without any increase in decoder complexity. The effectiveness of the approach is evaluated using both objective and subjective tests. This minimum-drift approach is very simple to implement and can also be applied for memory reduction of a full-resolution HDTV decoder.