Telefonaktiebolaget Lm Ericsson (publ)

Torbj&ouml;rn Einarsson

Per Thorell

Filippo Passaggio

Krister Svanbro

Rickard Sj&ouml;berg

Per Fr&ouml;jdh

A method and apparatus for maximizing the prediction utility of previously encoded macroblocks by adjusting the scanning order of the blocks within a macroblock to be encoded is disclosed. Where no previously encoded blocks are available above the macroblock being encoded, the alternative scanning orders allow for maximum utility of previously encoded blocks located to the left of the macroblock being encoded. Where no previously encoded blocks are available either above or to the left of the macroblock being encoded, the alternative scanning orders allow for maximum utility of information from blocks that are presently being encoded in the same macroblock. The particular scanning order used may be signaled implicitly based on the location of the macroblock being encoded, or it may be signaled explicitly by code words within the bitstream containing the encoded block information. In the case where the scanning order is to be signaled explicitly by a code word, the optimal scanning order may be chosen from among one or more scanning orders for any particular picture and macroblock.

Alternative block orders for better prediction

The present invention is directed to providing a method and apparatus for efficiently compressing and reconstructing a header of a real time communication packet. In a header compressor, a header field value is applied to a modulo X operator which can, for example, divide the header field value by a value X, and output the remainder. Optionally, a checksum may be appended to the remainder. The header field value may be scaled prior to being applied to the modulo X operator. The compressed header field which is output from the header compressor includes the remainder with or without the checksum appended. A header decompressor includes a field reconstructor which reconstructs the received compressed header field in response to the remainder value and range information. The range information represents a range of possible field values which can be reconstructed from the received remainder value.

Packet header compression using division remainders

In a method and a device for coding binary matrices, in particular sparse binary matrices, a matrix is gradually partitioned into sub-matrices During the gradual partitioning the number of binary ones are counted for each resulting sub-matrix. If a resulting sub-matrix does not consist of mixed symbols no further partitioning of that sub-matrix is required. The counted number of binary ones for each sub-matrix is then coded and transmitted. The method provides an efficient coding particularly for sparse binary matrices such as bi-level images or bit maps.

Lossless image compression with tree coding

In a method and a device for transforming a stream of digital numbers, the correlation between successive numbers is utilized in order to obtain a new stream having a very low correlation between the numbers, whereby the sequence of numbers can be coded much more efficiently from a compression point of view. The numbers are for this purpose coded with the difference between a predicted number (s&prime;(i)) and the actual number (s(i)) taking into account that the sequence does not need to be possible to decode in reverse order. The non-reversible codes can also be applied in lossy data compression schemes. Such schemes can change in accordance with the currently available bandwidth in order to obtain a graceful degradation and optimal bandwidth usage when the compressed data stream is transmitted over a channel having a time varying bandwidth. A general method and device for reversible coding are also provided.

Growing community of inventors

Stockholm, Sweden

Torbjörn Einarsson

Growing community of inventors

Stockholm, Sweden

Torbj&ouml;rn Einarsson

Torbjörn Einarsson