Title :
A wavelet codec with overlapped motion compensation for very low bit-rate environment
Author :
Katto, Jiro ; Ohki, Jun-Ichi ; Nogaki, Satoshi ; Ohta, Mutsumi
Author_Institution :
Inf. Technol. Res. Lab., NEC Corp., Kanagawa, Japan
fDate :
6/1/1994 12:00:00 AM
Abstract :
The paper describes theories on overlapped motion compensation and their applications to a wavelet codec aimed for the very low bit-rate environment below 64 kb/s. The theories are concerned with the evaluation of prediction efficiency improved by overlapped motion compensation and also its smoothing effect on the discontinuities at block boundaries encountered when motion vectors do not coincide among neighboring blocks. They contribute to determine the optimum window shape for overlapped motion compensation in a developed wavelet codec, which suffers from reduction of coding efficiency when there are such discontinuities in a signal to be transformed. Regarding the wavelet codec, a new scanning method of transform coefficients and alternate use of normal and spatially-reversed basis functions for the cascaded wavelet transform are introduced. Finally, the implementation of the codec on a video image signal processor (VISP) is discussed
Keywords :
codecs; filtering and prediction theory; image coding; motion estimation; wavelet transforms; VISP; basis functions; block boundaries; cascaded wavelet transform; coding efficiency; discontinuities; motion vectors; optimum window shape; overlapped motion compensation; prediction efficiency; scanning method; smoothing; transform coefficients; very low bit-rate environment; video image signal processor; wavelet codec; Codecs; Discrete cosine transforms; Discrete transforms; Motion compensation; Motion estimation; Shape; Signal processing; Smoothing methods; Video coding; Wavelet transforms;
Journal_Title :
Circuits and Systems for Video Technology, IEEE Transactions on
