Method and apparatus for temporal wavelet compression

Abstract

A system is described that comprises a method and apparatus for further compressing an already compressed data stream, using a mathematical comparison computation. The method comprises: receiving a data stream that has been compressed using a first compression protocol; decompressing the data stream using the first compression protocol; reducing temporal redundancy in the data stream using a comparison protocol; and recompressing the data stream using the first compression protocol. The apparatus comprises: a decompression unit to receive and decompress a compressed data stream to produce decompressed data; a comparison unit, coupled to the decompression unit, to perform a mathematical comparison operation on the decompressed data to produce resultant data; and a recompression unit to compress the resultant data to produce a further compressed data stream.

1 . A method for further compressing a compressed data stream, comprising:
 receiving a data stream that has been compressed using a first compression protocol and a second compression protocol;   decompressing the data stream using the first compression protocol;   reducing temporal redundancy in the data stream using a comparison protocol; and   recompressing the data stream using the first compression protocol.   
     
     
         2 . The method as recited in  claim 1 , wherein the first compression protocol includes run-length encoding and entropy encoding of quantized data. 
     
     
         3 . The method as recited in  claim 2 , wherein the entropy encoding is Huffman encoding. 
     
     
         4 . The method as recited in  claim 1 , wherein the second compression protocol includes wavelet compression. 
     
     
         5 . The method as recited in  claim 1 , further comprising:
 determining whether a recompressed data stream resulting from said recompressing is further compressed than the received data stream; and   discarding the recompressed data stream if it is not further compressed than the received data stream.   
     
     
         6 . A computer-readable medium storing computer-executable instructions to perform a method comprising:
 receiving a data stream that has been compressed using a first compression protocol and a second compression protocol;   decompressing the data stream using the first compression protocol;   reducing temporal redundancy in the data stream using a comparison protocol; and   recompressing the data stream using the first compression protocol.   
     
     
         7 . The computer-readable medium as recited in  claim 6 , wherein the first compression protocol includes run-length encoding and entropy encoding of quantized data. 
     
     
         8 . The computer-readable medium as recited in  claim 7 , wherein the entropy encoding is Huffman encoding. 
     
     
         9 . The computer-readable medium as recited in  claim 6 , wherein the second compression protocol includes wavelet compression. 
     
     
         10 . The computer-readable medium as recited in  claim 6 , further comprising:
 determining whether a recompressed data stream resulting from said recompressing is further compressed than the received data stream; and   discarding the recompressed data stream if it is not further compressed than the received data stream.   
     
     
         11 . An apparatus to further compress a compressed data stream, comprising:
 means for receiving a data stream that has been compressed using a first compression protocol and a second compression method;   means for decompressing the data stream using the first compression protocol;   means for reducing temporal redundancy in the data stream using a comparison protocol; and   means for recompressing the data stream using the first compression protocol.   
     
     
         12 . The apparatus as recited in  claim 11 , wherein the first compression protocol includes a run-length encoding and an entropy encoding of quantized data. 
     
     
         13 . The apparatus as recited in  claim 12 , wherein the entropy encoding is Huffman encoding. 
     
     
         14 . The apparatus as recited in  claim 11 , wherein the second compression protocol includes wavelet compression. 
     
     
         15 . The apparatus as recited in  claim 11 , further comprising:
 means for determining whether a recompressed data stream resulting from said recompressing is further compressed than the received data stream; and   means for discarding the recompressed data stream if it is not further compressed than the received data stream.   
     
     
         16 . An apparatus to further compress a compressed data stream, comprising:
 a decompression unit to receive and partially decompress the compressed data stream to produce partially decompressed data;   a comparison unit, coupled to the decompression unit, to perform a mathematical compare operation on the decompressed data to produce resultant data; and   a recompression unit to compress the resultant data to produce a further compressed data stream.   
     
     
         17 . The apparatus as recited in  claim 16 , wherein said decompression unit comprises:
 an entropy encoding/decoding unit, to receive the compressed data stream and to decode the compressed data stream to produce decoded data; and   a run-length encoding/decoding unit, coupled to said entropy encoding/decoding unit and said comparison unit, to further decode the decoded data into quantized data supplied to said comparison unit as the partially decompressed data.   
     
     
         18 . The apparatus as recited in  claim 17 , wherein the entropy encoding/decoding unit is a Huffman entropy encoder/decoder. 
     
     
         19 . The apparatus as recited in  claim 17 , wherein said recompression unit shares said entropy encoding/decoding and run-length encoding/decoding units with said decompression unit by
 said run-length encoding/decoding unit encoding the resultant data after said comparison unit processes the quantized data, to produce encoded data, and   said entropy encoding/decoding unit compressing the encoded data to produce the further compressed data.   
     
     
         20 . The apparatus as recited in  claim 16 , wherein said comparison unit performs the comparison operation by calculating qn[x,y,b]=qn[x,y,b]⊕q(n−1)[x,y,b], where n is the frame number, and where q is a quantized wavelet coefficient at a point determined by pixel locations x and y in the wavelet band corresponding to value b.