Method for coding a data stream

A method for emitting a data stream, the method comprising:

• coding the data stream, the data stream comprising a plurality of characters that are symbols from an alphabet, the characters in the data stream being combined to form a plurality of blocks, and the plurality of blocks being entropy-coded based on a code table valid for the respective block, the coding comprising:
• assigning the blocks to a plurality of clusters using an iteration based on a clearance that is defined such that the clearance between a block and a cluster of the plurality of clusters is smaller the smaller the change in the entropy of the cluster when adding the block to the cluster, the blocks being reassigned to the clusters in a respective iteration step of the iteration by respectively assigning the blocks to the cluster with the smallest clearance between the block and the cluster;
• and
• respectively assigning a code table to the clusters determined by the iteration, the code table being determined based on a frequency distribution of the symbols in at least some of the blocks contained in the respective cluster and being valid for all blocks in the respective cluster;
• and
• emitting the coded data stream, the code tables for the plurality of clusters, and information relating to the blocks for which the code tables are valid,
• wherein the iteration is initialized such that a plurality of clusters comprising a block is determined, and the remaining blocks are respectively assigned to the cluster with the smallest clearance between the block and the cluster.

A transmitting apparatus for emitting a data stream, the transmitting apparatus comprising:

• a coding device operable to code a data stream, the data stream comprising a plurality of characters that are symbols from an alphabet, the plurality of characters in the data stream being combined to form a plurality of blocks, the coding device operable to subject the blocks to entropy coding based on a code table valid for the respective block, the coding device comprising:
• a first means for assigning the blocks to a plurality of clusters using an iteration based on a clearance that is defined such that the clearance between a block and a cluster┐ is smaller the smaller a change in the entropy of the cluster when adding the block to the cluster, the blocks being reassigned to the clusters in a respective iteration step of the iteration by respectively assigning the blocks to the cluster with the shortest distance between the block and the cluster;
• and
• a second means for respectively assigning a code table to the clusters determined by the iteration, the code table being determined using the second means based on a frequency distribution of symbols in at least some of the blocks contained in the respective cluster and being valid for all blocks in the respective cluster;
• and
• a means for emitting the data stream coded using the coding device, code tables for the plurality of clusters, and information relating to the blocks for which the code tables are valid.

A method for transmitting a data stream, the method comprising:

• emitting the data stream, the emitting comprising:
• coding the data stream, the data stream comprising a plurality of characters that are symbols from an alphabet, the characters in the data stream being combined to form a plurality of blocks, and the plurality of blocks being entropy-coded based on a code table valid for the respective block, the coding comprising:
• assigning the blocks to a plurality of clusters using an iteration based on a clearance that is defined such that the clearance between a block and a cluster of the plurality of clusters is smaller the smaller the change in the entropy of the cluster when adding the block to the cluster, the blocks being reassigned to the clusters in a respective iteration step of the iteration by respectively assigning the blocks to the cluster with the smallest clearance between the block and the cluster;
• and
• respectively assigning a code table to the clusters determined by the iteration, the code table being determined based on a frequency distribution of the symbols in at least some of the blocks contained in the respective cluster and being valid for all blocks in the respective cluster;
• and
• emitting the coded data stream, the code tables for the plurality of clusters, and information relating to the blocks for which the code tables are valid;
• receiving, by a receiving apparatus, the data stream, the receiving apparatus decoding the coded data stream with the aid of the code tables for the plurality of clusters and the information relating to the blocks for which the code tables are valid,
• wherein the iteration is initialized such that a plurality of clusters comprising a block is determined, and the remaining blocks are respectively assigned to the cluster with the smallest clearance between the block and the cluster.

An apparatus for transmitting a data stream, the apparatus comprising;

• a transmitting apparatus for emitting the data stream, the transmitting apparatus comprising:
• a coding device operable to code a data stream, the data stream comprising a plurality of characters that are symbols from an alphabet, the plurality of characters in the data stream being combined to form a plurality of blocks, the coding device operable to subject the blocks to entropy coding based on a code table valid for the respective block, the coding device comprising:
• a first means for assigning the blocks to a plurality of clusters using an iteration based on a clearance that is defined such that the clearance between a block and a cluster┐ is smaller the smaller a change in the entropy of the cluster when adding the block to the cluster, the blocks being reassigned to the clusters in a respective iteration step of the iteration by respectively assigning the blocks to the cluster with the shortest distance between the block and the cluster;
• and
• a second means for respectively assigning a code table to the clusters determined by the iteration, the code table being determined using the second means based on a frequency distribution of symbols in at least some of the blocks contained in the respective cluster and being valid for all blocks in the respective cluster;
• and
• a means for emitting the data stream coded using the coding device, code tables for the plurality of clusters, and information relating to the blocks for which the code tables are valid;
• and
• a receiving apparatus comprising a receiver and a decoder, the receiver operable to receive the coded data stream, the code tables for the plurality of clusters, and the information relating to the blocks for which the code tables are valid, the decoder being operable to decode the coded data stream with the aid of the code tables and the information relating to the blocks for which the code tables are valid.