Wavelet domain half-pixel motion compensation

An encoding process comprising:

• performing a wavelet transformation on a first frame of video data to generate first wavelet domain data;
• generating half-pixel data from the first wavelet domain data, wherein the half-pixel data approximates wavelet domain data resulting from a wavelet transform of matrices that are offset relative to matrices used during the wavelet transform;
• searching wavelet domain data and the half-pixel data for a block that best matches an object block from second wavelet domain data representing a second frame;
• and
• including in a data stream representing the second frame a motion vector that identifies the block that best matches the object block.

A video decoding process comprising:

• decoding a data structure to extract a difference array and motion vectors associated with a first frame of video, the difference array containing a difference between wavelet domain data;
• for each motion vector, identifying whether the motion vector is of a first type or a second type, wherein:
• motion vectors of the first type identify respective blocks of wavelet domain data representing a second frame;
• and
• motion vectors of the second type identify respective blocks of data corresponding to an approximation of a wavelet transform of a matrix of pixel values representing a portion of the second frame, the matrix being offset relative to matrices used in generating the wavelet domain data representing the second frame;
• adding the respective blocks of wavelet domain data identified by motion vectors of the first type to respective portions of the difference array;
• and
• for each motion vector of the second type, generating from the wavelet domain data representing the second frame the block of data identified by the motion vector of the second type, and adding the block thus generated to a portion of the difference array corresponding to the motion vector of the second type.

A data structure representing video comprising:

• first data indicating wavelet domain data for a first frame of the video;
• second data indicating a difference array for a second frame of the video;
• motion vectors of a first type, wherein the motion vectors of the first type correspond to respective blocks in the difference array and identify blocks of the wavelet domain data for addition to the respective blocks in the difference array when generating wavelet domain data for the second frame;
• and
• motion vectors of a second type, wherein the motion vectors of the second type correspond to respective blocks in the difference array and identify blocks of half-pixel data for addition to the respective blocks in the difference array when generating the wavelet domain data for the second frame, the half-pixel data approximating wavelet transforms of arrays from the first frame that are offset relative to arrays from the first frame that were used in generating the wavelet domain data for the first frame.