Arithmetic encoder for arithmetically encoding and arithmetic decoder for arithmetically decoding a sequence of information values, methods for arithmetically encoding and decoding a sequence of information values and computer program for implementing these methods

An arithmetic decoder for arithmetically decoding a sequence of information values from a bitstream, configured to:

• derive from the bitstream entry point information;
• use the entry point information so as to resume arithmetically decoding the bitstream from a predetermined entry point onward by arithmetically decoding a sequence of symbols from the bitstream by, for each symbol of the bitstream:
• determining, based on a current version of a coding state of the arithmetic decoder, a subinterval out of a plurality of subintervals into which a current interval is subdivided according to a probability estimate for the respective symbol, and deduce, based on the selected subinterval, a symbol value of the respective symbol, and
• renormalizing and updating decoder-internal parameters which define the coding state by use of the bitstream and the selected subinterval so as to acquire an updated version of the coding state of the arithmetic decoder for decoding a next symbol of the sequence of symbols, and
• derive the information values from the sequence of symbols by desymbolization.

A method of arithmetically encoding a sequence of information values into an arithmetic coded bitstream, comprising:

• symbolizing the information values into symbol strings so as to acquire a sequence of symbols;
• arithmetically encoding the sequence of symbols by
• subdividing a current interval, which defines a current version of a coding state of an arithmetic encoder, for each symbol, according to a probability estimate for the respective symbol,
• selecting a subinterval out of a plurality of the subintervals according to a symbol value of the respective symbol so as to acquire an updated version of the coding state of the arithmetic encoder, defined by the selected subinterval, for encoding a next symbol of the sequence of symbols, and
• renormalizing encoder-internal parameters which define the coding state under continuing the bitstream,
• providing the bitstream with entry point information allowing for resuming arithmetic decoding the bitstream from a predetermined entry point onward.

A method of arithmetically decoding a sequence of information values from a bitstream, comprising:

• deriving from the bitstream entry point information;
• using the entry point information so as to resume arithmetically decoding the bitstream from a predetermined entry point onward by arithmetically decoding a sequence of symbols from the bitstream by, for each symbol of the bitstream:
• determining, a current version of a coding state of an arithmetic decoder, a subinterval out of a plurality of subintervals into which a current interval is subdivided according to a probability estimate for the respective symbol, and deducing, based on the selected subinterval, a symbol value of the respective symbol, and
• renormalizing and updating decoder-internal parameters which define the coding state by use of the bitstream and the selected subinterval so as to acquire an updated version of the coding state of the arithmetic decoder for decoding a next symbol of the sequence of symbols, and
• deriving the information values from the sequence of symbols by desymbolization.

A non-transitory digital storage medium having a computer program stored thereon to perform the method of arithmetically encoding a sequence of information values into an arithmetic coded bitstream, comprising:

• symbolizing the information values into symbol strings so as to acquire a sequence of symbols;
• arithmetically encoding the sequence of symbols by
• subdividing a current interval, which defines a current version of a coding state of an arithmetic encoder, for each symbol, according to a probability estimate for the respective symbol,
• selecting a subinterval out of a plurality of the subintervals according to a symbol value of the respective symbol so as to acquire an updated version of the coding state of the arithmetic encoder, defined by the selected subinterval, for encoding a next symbol of the sequence of symbols, and
• renormalizing encoder-internal parameters which define the coding state under continuing the bitstream,
• providing the bitstream with entry point information allowing for resuming arithmetic decoding the bitstream from a predetermined entry point onward,
• when said computer program is run by a computer.

A non-transitory digital storage medium having a computer program stored thereon to perform the method of arithmetically decoding a sequence of information values from a bitstream, comprising:

• deriving from the bitstream entry point information;
• using the entry point information so as to resume arithmetically decoding the bitstream from a predetermined entry point onward by arithmetically decoding a sequence of symbols from the bitstream by, for each symbol of the bitstream:
• determining, a current version of a coding state of an arithmetic decoder, a subinterval out of a plurality of subintervals into which a current interval is subdivided according to a probability estimate for the respective symbol, and deducing, based on the selected subinterval, a symbol value of the respective symbol, and
• renormalizing and updating decoder-internal parameters which define the coding state by use of the bitstream and the selected subinterval so as to acquire an updated version of the coding state of the arithmetic decoder for decoding a next symbol of the sequence of symbols, and
• deriving the information values from the sequence of symbols by desymbolization,
• when said computer program is run by a computer.