Abstract: Decoding and encoding of variable length data words and data strings is accelerated by testing for and processing more than one word or string per encoding or decoding cycle. In an encoding scheme wherein fixed length data words are encoded into variable length data strings, decoding is carried out by first receiving a data stream having a plurality of encoded data strings contained therein, and then testing at least a portion of the data stream to determine whether the portion contains one of a number of selected sets of multiple data strings. If the portion of the data stream contains one of the selected sets of multiple data strings, the multiple data strings are decoded into a corresponding set of multiple data words. This decoding procedure allows a plurality of encoded data strings to be decoded in a single decoding cycle. The procedure may be implemented using either a single lookup table or a set of split-level lookup tables.

Abstract: Improved proprecessing and postprocessing for vector quantization, for example, for encoding an image. In one embodiment, the luminosity of the vectors in an image are used to determine the codes for vector quantization. In another embodiment, a median filter is performed to eliminate motion artifacts. In another embodiment, temporal filtering is applied once the difference between an earlier frame and a current frame exceeds a threshold. Embodiments are also provided for adaptive temporal filtering based on temporal "no change" blocks and their errors. Embodiments are provided for different regions of images which reference different codebooks, and regions of variable size. Embodiments are also provided for shared and variable size codebooks for different images or other data.

Abstract: Data packets which have been sequentially encoded and transmitted, and are received out-of-sequence, are decoded, such that the proper sequence is restored. A receiving decoder is synchronized with a transmitting encoder and generates a sequence of decoding data corresponding to the sequence used to encode the data. The decoding data is combined with the received encoded data to produce the original dam. The decoded data is then stored in message-sequence in a memory. When packet network routing results in the encoded data being received out-of-sequence, a portion of the generated sequence of decoding data corresponding to packets that have not been received is saved in a memory. When the out-of-sequence packet of encoded data is received, the stored portion of the decoding data is retrieved from memory and is combined with the packet data to produce the decoded data, which is then stored in message sequence.

Abstract: An apparatus and method for processing video data for compression/decompression in real-time. The apparatus comprises a plurality of compute modules, in a preferred embodiment, for a total of four compute modules coupled in parallel. Each of the compute modules has a processor, dual port memory, scratch-pad memory, and an arbitration mechanism. A first bus couples the compute modules and a host processor. Lastly, the device comprises a shared memory which is coupled to the host processor and to the compute modules with a second bus. The method handles assigning portions of the image for each of the processors to operate upon.

Abstract: An apparatus and method for improving the security of an electronic codebook encryption scheme comprises a transmitter unit for encoding or encrypting data and a separate authorized receiver for decoding or decrypting data. Both the transmitter and receiver share a common secret key that has been communicated through a separate channel.The transmitter includes a Mapping Table (MTable) that comprises a table of functions, where a first series of incrementally numbered expressions are equated with a second series of randomly generated numbers. The plaintext is input into the transmitter and applied to the MTable to provide ciphertext. The PN generator supplies a unique random sequence of binary digits. The ciphertext byte and random number byte associated with each byte of plaintext data are exchanged to change the relationships within the MTable.

Abstract: A method and apparatus for improving the security of an electronic codebook encryption scheme comprises a transmitter unit for encoding or encrypting data and a separate authorized receiver for decoding or decrypting the data. During the encryption of the plaintext data, a randomly generated offset is introduced into the PN sequence to vary the starting point of the PN sequence as it is applied to the plaintext data. The offset is encrypted with the secret key and the unencrypted IV, encrypted offset, and ciphertext are exported by the transmitter to the receiver for decrypting.The encoded communication is imported by the receiver and the encrypted offset portion is extracted. The receiver combines the encrypted offset with the secret key to decipher the offset value. The offset and PN sequence are then combined with the ciphertext, using an XOR gate, to recover the original plain text from the ciphertext.

Abstract: A method and apparatus for decoding a variable length codeword (VLC) by reading a VLC, the VLC having a maximum length of X bits. The VLC is used as an index into a first table, wherein the first table contains decoded values for all possible VLC's with Y bits not equal to any value in a first set of values. Y is typically less than X and comprises, in the preferred embodiment, the most significant bits of the VLC. If the first Y bits of the VLC are not equal to any value in a first set of values then a second value is returned from the first table. If the first Y bits of the VLC are equal to any value in a first set of values, then a pointer to a second table is returned from the first table. The VLC is used as an index into the second table, and a third value is returned from the second table.

Abstract: An apparatus and method for processing video data for compression/decompression in real-time. The apparatus comprises a plurality of compute modules, in a preferred embodiment, for a total of four compute modules coupled in parallel. Each of the compute modules has a processor, dual port memory, scratch-pad memory, and an arbitration mechanism. A first bus couples the compute modules and a host processor. Lastly, the device comprises a shared memory which is coupled to the host processor and to the compute modules with a second bus. The method handles assigning portions of the image for each of the processors to operate upon.