Audio coding

An encoder comprising

• a transform unit adapted to receive a time domain input audio signal, to transform the audio signal into a frequency domain signal, and to split the frequency domain audio signal into at least two sub-bands,
• a scaling unit adapted to scale at least two sub-bands with a scaling factor,
• a conditional split lattice quantizer unit adapted to quantize the scaled sub-bands outputting a lattice codevector for each sub-band, and
• an encoding unit adapted to encode at least information relating to the scaling factor and information relating to the number of bits on which the lattice codevectors are represented.

An electronic device comprising

• a transform unit adapted to receive a time domain input audio signal, to transform the audio signal into a frequency domain signal, and to split the frequency domain audio signal into at least two sub-bands,
• a scaling unit adapted to scale at least two sub-bands with a scaling factor,
• a conditional split lattice quantizer unit adapted to quantize the scaled sub-bands outputting a lattice codevector for each sub-band, and
• an encoding unit adapted to encode at least information relating to the scaling factor and information relating to the number of bits on which the lattice codevectors are represented.

A software program product, in which a software code for audio encoding is stored, said software code realizing the following steps when being executed by a processing unit of an electronic device:

• receive the input audio signal,
• transform the time domain audio signal into frequency domain,
• split the frequency domain audio signal into at least two sub-bands,
• scale the at least two sub-bands with a scaling factor,
• quantize the scaled sub-bands using a conditional split lattice quantizer, wherein the output of the conditional split lattice quantizer is a lattice codevector for each sub-band, and
• encode at least information relating to the scaling factor and information relating to the number of bits on which the lattice codevectors are represented.

A method for decoding an encoded audio signal with

• receiving the encoded audio signal,
• entropy decoding the encoded audio signal obtaining at least information about the number of bits of lattice codevectors and scaling factors of sub-bands,
• obtaining, for each sub-band, a codevector index from an encoded bitstream codeword whose length equals the number of bits of the lattice codevector and obtaining the lattice codevector from the codevector index,
• re-scaling, for each sub-band, the obtained codevector by applying the scaling factor and obtaining the frequency representation of the audio signal, and
• inverse transforming the frequency representation of the signal into time domain.

A decoder comprising

• an entropy decoding unit adapted to entropy decode an encoded audio signal obtaining at least information about the number of bits of lattice codevectors and scaling factors of sub-bands,
• an inverse indexing unit arranged to obtain, for each sub-band, a codevector index from an encoded bitstream codeword of length equal to the number of bits of the lattice codevector and to obtain the lattice codevector from the codevector index,
• a scaling unit adapted to re-scale, for each sub-band, the obtained codevector by applying the scaling factor, and
• an inverse transform unit to transform the frequency representation of the signal into time domain.

An electronic device comprising

• an entropy decoding unit adapted to entropy decode an encoded audio signal obtaining at least information about the number of bits of lattice codevectors and scaling factors of sub-bands,
• an inverse indexing unit arranged to obtain, for each sub-band, a codevector index from an encoded bitstream codeword of length equal to the number of bits of the lattice codevector and to obtain the lattice codevector from the codevector index,
• a scaling unit adapted to re-scale, for each sub-band, the obtained codevector by applying the scaling factor, and
• an inverse transform unit to transform the frequency representation of the signal into time domain.

A software program product, in which a software code for audio decoding is stored, said software code realizing the following steps when being executed by a processing unit of an electronic device:

• receive the encoded audio signal,
• entropy decode the encoded audio signal to obtain at least information about the number of bits of lattice codevectors and scaling factors of sub-bands,
• obtain, for each sub-band, a codevector index from an encoded bitstream codeword whose length equals the number of bits of the lattice codevector and obtain the lattice codevector from the codevector index,
• re-scale, for each sub-band, the obtained codevector by applying the scaling factor and obtain the frequency representation of the audio signal, and
• inverse transform the frequency representation of the signal into time domain.