METHOD AND APPARATUS FOR TEMPORAL WAVELET COMPRESSION

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.