Method of coding a video signal whereby pictures can be reproduced with a high quality and a device therefor

A coding device for coding a digital video signal which is representative of successive pictures by using a correlation between said successive pictures, each of said successive pictures being divisible into a predetermined number of blocks of picture elements, said coding device comprising:

• detecting means for detecting an original motion vector representative of movement of each block between two of said pictures:
• predictive coding means for predictably conding said digital video signal by using said original motion vector to produce a coded signal;
• separating means for separating said blocks into a moving part and a still part, said moving part having substantially all of said movement, said still part having substantially no movement, said separating means thereby producing a separating signal representative of said moving and said still parts;
• processing means responsive to said separating signal for processing said separating signal into an on-off control signal indicative of whether subsampling is turned on and off at each of said blocks;
• subsampling means responsive to said on-off control signal for subsampling said coded signal into a subsampled signal and into a non-subsampled signal when said on-off control signal indicates on and off, respectively, at each of said blocks;
• first code-converting means for converting said subsampled and said non-subsampled signals into a converted code signal;
• second code-converting means for converting said original motion vector and said on-off control signal into a converted motion vector signal and a converted control signal which is distinguishable from said converted code signal and said converted motion vector signal;
• and
• multiplexing means for multiplexing said converted code signal, said converted motion vector signal, and said converted control signal into a multiplexed signal.

A decoding device for decoding a multiplexed signal which was produced by a coding device for coding a digital video signal representative of successive pictures by using a correlation between said successive pictures, each of said successive pictures being divisible into a predetermined number of blocks of picture elements, said coding device comprising:

• detecting means for detecting an original motion vector representative of a movement of each block between two of said pictures;
• predictive coding means for predictably coding said digital video signal by using said original motion vector to produce a coded signal;
• separting means for separating said blocks into a moving part and a still part, said moving part having substantially all of said movement, said still part having substantially no movement, said separating means thereby producing a separating signal representative of said moving and said still parts;
• processing means responsive to said separating signal for processing said separating signal into an on-off control signal indicative of whether subsampling is turned on and off at each of said blocks;
• subsampling means reponsive to said on-off control signal for subsampling said coded signal into a subsampled signal and into a non-subsampled signal when said on-off control signal indicates on and off of said subsampling, respectively;
• first code-converting means for converting both said subsampled and said non-subsampled signals into a converted code signal;
• and
• second code-converting means for converting both said original motion vector and said on-off control signal into a converted motion vector signal and a converted control signal which is distinguishable from said motion vector signal and said converted code signal;
• said multiplexed signal being produced by multiplexing said converted code signal, said converted motion vector signal, and said converted control signal;
• said decoding device comprising:
• first inverse code-converting means for converting said converted motion vector signal and said converted control signal which is distinguishable from said converted motion vector signal, into a reproduction of said original motion vector and said on-off control signal;
• second inverse code-converting means responsive to said reproduction of the on-off control signal for converting said converted code signal into a reproduction of said coded signal with reference to said reproduction of the on-off control signal;
• and
• predictive decoding means for predictably decoding said reproduction of the coded signal by using said reproduction of the original motion vector to produce said digital video signal.