Apparatus and method for memory saving wavelet based video coding

A method of video compression comprising:

• row by row horizontal subband filtering of video data representing part of an image;
• and
• row by row concurrent vertical high and vertical low pass subband filtering of the results of the horizontal subband filtering wherein less than the vertical filter length of rows of results of the horizontal subband filtering are buffered at a time, wherein said vertical high and vertical low pass subband filtering includes:
• calculating a final value for a current row of results of the vertical low pass subband filtering based on a first row of a recursion buffer and a row of results of the horizontal subband filtering,
• calculating a final value for a current row of results of the vertical high pass subband filtering based on a second row of the recursion buffer and the row of results of the horizontal subband filtering,
• calculating an intermediate value of a next row of results of the vertical high pass subband filtering based on the row of results of the horizontal subband filtering,
• calculating an intermediate value of a next row of results of the vertical low pass subband filtering based on the row of results of the horizontal subband filtering and the second row of the recursion buffer,
• transmitting said current row of results of the vertical high pass filtering to be encoded,
• storing said intermediate value of the next row of results of the vertical high pass subband filtering in said first row of the recursion buffer, and
• storing said intermediate value of the next row of results of the vertical low pass subband filtering in said second row of the recursion buffer.

A method of video compression comprising:

• row by row horizontal subband filtering of video data representing part of an image;
• and
• row by row concurrent vertical high and vertical low pass subband filtering of the results of the horizontal subband filtering wherein less than the vertical filter length of rows of results of the horizontal subband filtering are buffered at a time, wherein the vertical high and vertical low pass subband filtering includes:
• priming a recursion buffer,
• as each result row of horizontal subband filtering is generated, updating two rows of the recursion buffer based on vertical filter coefficients, the current result row of horizontal filter coefficients and at least one row of the recursion buffer, and
• as certain rows of the result of the horizontal subband filtering are generated, generating a result row of vertical high and vertical low pass subband filtering based on vertical coefficients, the current result row of horizontal filter coefficients, and the contents of the two rows of the recursion buffer.