US 6,611,798 B2 · Perceptually improved encoding of acoustic signals

Abstract

Encoding an acoustic source signal such that a signal {circumflex over (z)} reconstructed from the encoded information has a perceptually high sound quality. The acoustic source signal is encoded into at least one basic coded signal that represents perceptually significant characteristics of the acoustic signal. The encoder can include at least one spectral smoothing unit which receives at least one of the signal components on which the basic coded signal is based and generates in response thereto a corresponding smoothed signal component. At least one enhanced coded signal is then produced from the corresponding smoothed signal. component for transmission. A receiver receives at least one estimate {circumflex over (P)}E of the transmitted signal(s), and a spectral smoothing unit in the receiver produces, on basis of a primary spectrum Ŷ decoded from the at least one received estimate {circumflex over (P)}E, a smoothed primary decoded spectrum ŶE. Finally, this signal ŶE is used to generate an enhanced estimate {circumflex over (z)} of the acoustic source signal. ŶE.

Claims44

Dependent claims

A method of encoding an acoustic source signal to produce encoded information for transmission over a transmission medium, comprising:

producing, in response to the acoustic source signal,
a basic coded signal representing perceptually significant characteristics of the acoustic signal;
a target signal representing a filtered version of the acoustic source signal;
and
a primary coded signal representing a reconstructed signal based on the basic coded signal;
producing, in response to at least one of the primary coded signal and the target signal a corresponding smoothed signal constituting a perceptually improved representation of the primary coded signal respective the target signal;
and
producing a secondary coded signal on basis of a combination of either:
the smoothed primary coded signal and the target signal;
the primary coded signal and the smoothed target signal;
or
the smoothed primary coded signal and the smoothed target signal, wherein:
the primary coded signal comprises coefficients of which each coefficient represents a frequency component;
the target signal comprises coefficients of which each coefficient represents a frequency component;
and
the corresponding smoothed signals are selectively modified versions of the primary coded signal respective the target signal wherein a variation is reduced in the coefficient values representing frequency information above a threshold value.

13 more elements

A transmitter for encoding an acoustic source signal to produce encoded information for transmission over a transmission medium, comprising:

a primary coder having an input to receive the acoustic source signal and having a first output for providing a basic coded signal representing perceptually significant characteristics of the acoustic signal from which an estimate of the acoustic source signal can be reconstructed, a second output for providing a target signal representing a filtered version of the acoustic source signal, a third output for providing a primary coded signal representing a reconstructed signal based on the basic coded signal;
at least one spectral smoothing unit for producing, in response to the primary coded signal, a smoothed primary coded signal constituting a perceptually improved representation of the primary coded signal;
a quantizer for producing a secondary coded signal on basis of the smoothed primary coded signal and the target signal, wherein:
the at least one spectral smoothing unit is devised to produce a smoothed output signal from the primary coded signal by selectively modifying the primary coded signal such that a variation is reduced in coefficient values thereof representing frequency information above a threshold value.

1 more element

A receiver for decoding an estimate of a representation of an acoustic source signal from encoded information received from a transmission medium, comprising a spectral smoothing unit having an input to receive a primary decoded spectrum being derived from the received encoded information and an output to provide a smoothed primary decoded spectrum, wherein the smoothed primary decoded spectrum comprises coefficients of which each coefficient represents a frequency component, the spectral smoothing unit being devised to produce the smoothed primary decoded spectrum by selectively modifying the primary decoded spectrum such that a variation is reduced in coefficient values representing frequency information above a threshold value.

Dependencies are inferred from the claim text.

Perceptually improved encoding of acoustic signals

Life of this patent

Perceptually improved encoding of acoustic signals

Life of this patent

Abstract

Claims44