The speech encoding apparatus (220) has a first layer encoding section (2201), a first layer decoding section (2202), a delay section (2203), a subtracting section (104), a frequency domain transforming section (101), a second layer encoding section (105) and a multiplexing section (106).

Encoding device, decoding device, and method thereof

Applications of dim-and-burst techniques to coding of wideband speech signals are described. Reconstruction of a highband portion of a frame of a wideband speech signal using information from a previous frame is also described.

Systems, methods, and apparatus for wideband encoding and decoding of active frames

The following coding scenario is addressed: A number of audio source signals need to be transmitted or stored for the purpose of mixing wave field synthesis, multi-channel surround, or stereo signals after decoding the source signals. The proposed technique offers significant coding gain when jointly coding the source signals, compared to separately coding them, even when no redundancy is present between the source signals. This is possible by considering statistical properties of the source signals, the properties of mixing techniques, and spatial hearing. The sum of the source signals is transmitted plus the statistical properties of the source signals which mostly determine the perceptually important spatial cues of the final mixed audio channels. Source signals are recovered at the receiver such that their statistical properties approximate the corresponding properties of the original source signals. Subjective evaluations indicate that high audio quality is achieved by the proposed scheme.

Parametric joint-coding of audio sources

A noise suppression device comprises subband SN ratio calculation means which receives a noise likeness signal, an input signal spectrum and a subband-based estimated noise spectrum, calculates the subband-based input signal average spectrum, calculates a subband-based mixture ratio of the subband-based estimated noise spectrum to the subband-based input signal average spectrum on the basis of the noise likeness signal, and calculates the subband-based SN ratio on the basis of the subband-based estimated noise spectrum, the subband-based input signal average spectrum and the mixture ratio.

Noise suppression device

An encoding apparatus comprises a frame processor (105) which receives a multi channel audio signal comprising at least a first audio signal from a first microphone (101) and a second audio signal from a second microphone (103). An ITD processor (107) then determines an inter time difference between the first audio signal and the second audio signal and a set of delays (109, 111) generates a compensated multi channel audio signal from the multi channel audio signal by delaying at least one of the first and second audio signals in response to the inter time difference signal. A combiner (113) then generates a mono signal by combining channels of the compensated multi channel audio signal and a mono signal encoder (115) encodes the mono signal. The inter time difference may specifically be determined by an algorithm based on determining cross correlations between the first and second audio signals.

Apparatus and method for encoding a multi-channel audio signal

An encoder, decoder, encoding method, and decoding method enabling acquisition of high-quality decoded signal in scalable encoding of an original signal in first and second layers even if the second or upper layer section performs low bit-rate encoding In the encoder, a spectrum residue shape codebook (305) stores candidates of spectrum residue shape vectors, a spectrum residue gain codebook (307) stores candidates of spectrum residue gains, and a spectrum residue shape vector and a spectrum residue gain are sequentially outputted from the candidates according to the instruction from a search section (306) A multiplier (308) multiplies a candidate of the spectrum residue shape vector by a candidate of the spectrum residue gain and outputs the result to a filtering section (303) The filtering section (303) performs filtering by using a pitch filter internal state set by a filter state setting section (302), a lag T outputted by a lag setting section (304), and a spectrum residue shape vector which has undergone gain adjustment

Encoder, decoder, encoding method, and decoding method

A scalable decoding apparatus capable of providing decoded audio signals of high quality having less degradation of a high frequency spectrum even when decoding audio signals by generating the high frequency spectrum by use of a low frequency spectrum. In the apparatus, an amplitude adjusting part (1211) uses different adjustment coefficients in accordance with the characteristic of first layer spectrum information to adjust the amplitude of a first layer decoded signal spectrum, and then outputs the amplitude-adjusted first layer decoded signal spectrum to a pseudo-spectrum generating part (1012). Using amplitude-adjusted first layer decoded signal spectrum received from the amplitude adjusting part (1211), the pseudo-spectrum generating part (1012) generates and outputs a pseudo-spectrum of high frequencies to a scaling part (1013). The scaling part (1013) scales the spectrum received from the pseudo-spectrum generating part (1012) and then outputs it to an adder (B).

Scalable decoding apparatus and scalable encoding apparatus

Disclosed is a scalable encoding device capable of reducing an encoding rate thereby to reduce a circuit scale while preventing sound quality deterioration of a decoded signal. In this device, an extension layer is coarsely divided into a system for processing a first channel and a system for processing a second channel. A sound source prediction unit (112) for processing the first channel predicts the drive sound source signal of the first channel from the drive sound source signal of a monaural signal, and outputs the predicted drive sound source signal through a multiplier (113) to a CELP encoding unit (114). A sound source prediction unit (115) for processing the second channel predicts the drive sound source signal of the second channel from the drive sound source signal of the monaural signal and the output from the CELP encoding unit (114), and outputs the predicted drive sound source signal through a multiplier (116) to a CELP encoding unit (117). The CELP encoding units (114, 117) perform the CELP encoding operations of the individual channels by using the individual predicted drive sound source signals.

Scalable encoding device and scalable encoding method

The conventional error conceal processing generates a greatly fluctuating irregular sound which is unpleasant to ears and causes a remarkable echo effect and click noise. A notification signal detection unit (301) judges processing for an input frame. In case of an error frame, a sound detection unit (303) makes judgment whether a preceding non-error data frame is a sound signal. If it is a sound frame, a sound copying unit (304) generates a replacing frame. If it is a non-sound frame, a transient signal detection unit (305) judges whether it is an attack signal by the transient signal detection and selects an appropriate area from the preceding non-error frame. A filter bank analysis unit (306) generates N sub-bands. Sub-band samples are extrapolated to these by an extrapolation unit (307) and they become replacing sub-band data for the current error frame. From the data, a filter bank synthesis unit (308) rebuilds the sub-band data.

Error conceal device and error conceal method

A prediction performance between the individual channels of a stereo signal is improved to improve the sound quality of a decoded signal. An LPF (101-1) interrupts the high-range component of an S1, and outputs an S1' (a low-range component). An LPF (101-2) interrupts the high-range component of an S2, and outputs an S2' (a low-range component). A prediction unit (102) predicts the S2' from the S1', and outputs a prediction parameter composed of a delay time difference (t) and an amplitude ratio (g). A first channel encoding unit (103) encodes the S1. A prediction parameter encoding unit (104) encodes the prediction parameter. The encoded parameters of the encoded parameter of the S1 and the prediction parameter are finally outputted.

Koji Yoshida

Papers

Encoder, decoder, encoding method, and decoding method

Scalable decoding apparatus and scalable encoding apparatus

Scalable encoding device and scalable encoding method

Error conceal device and error conceal method

Stereo encoding device, and stereo signal predicting method