Voiceage Corporation

Voiceage Evs LLC

Vaclav Eksler

Redwan Salami

Milan Jelinek

Methods, an encoder and a decoder are configured for transition between frames with different internal sampling rates. Linear predictive (LP) filter parameters are converted from a sampling rate Sto a sampling rate S. A power spectrum of a LP synthesis filter is computed, at the sampling rate S, using the LP filter parameters. The power spectrum of the LP synthesis filter is modified to convert it from the sampling rate Sto the sampling rate S. The modified power spectrum of the LP synthesis filter is inverse transformed to determine autocorrelations of the LP synthesis filter at the sampling rate S. The autocorrelations are used to compute the LP filter parameters at the sampling rate S

Methods, encoder and decoder for linear predictive encoding and decoding of sound signals upon transition between frames having different sampling rates

A method and device for allocating a bit-budget to a plurality of first parts and to a second part of a CELP core module of (a) an encoder for encoding a sound signal or (b) a decoder for decoding the sound signal. In a frame of the sound signal comprising sub-frames, respective bit-budgets are allocated to the first CELP core module parts and a bit-budget remaining after allocating to the first CELP core module parts their respective bit-budgets is allocated to the second CELP core module part. According to an alternative, the second CELP core module part bit-budget is distributed between the sub-frames of the frame and a larger bit-budget is allocated to at least one of the sub-frames of the frame. The at least one sub-frame may be the first sub-frame of the frame, at least one sub-frame following the first sub-frame, or the sub-frame using a glottal-impulse-shape codebook.

Method and device for allocating a bit-budget between sub-frames in a CELP CODEC

A method and device allocates a bit-budget to a plurality of first parts of a CELP core module of (a) an encoder for encoding a sound signal or (b) a decoder for decoding the sound signal. In the method and device, bit-budget allocation tables assign, for each of a plurality of intermediate bit rates, respective bit-budgets to the first CELP core module parts. A CELP core module bit rate is determined and one of the intermediate bit rates is selected based on the determined CELP core module bit rate. The respective bit-budgets assigned by the bit-budget allocation tables for the selected intermediate bit rate are allocated to the first CELP core module parts.

Method and device for efficiently distributing a bit-budget in a CELP codec

Codebook Arrangement for use in coding an input sound signal includes First and Second Codebook Stages. First Codebook Stage includes one of a time-domain CELP codebook and a transform-domain codebook. Second Codebook Stage follows the first codebook stage and includes the other of the time-domain CELP codebook and the transform-domain codebook. Codebook Stage includes an adaptive codebook may be provided before First Codebook Stage. A selector may be provided to select an order of the time-domain CELP codebook and the transform-domain codebook in First and Second Codebook Stages, respectively, as a function of characteristics of the input sound signal. The selector may also be responsive to both the characteristics of the input sound signal and a bit rate of the codec using Codebook Arrangement to bypass Second Codebook Stage. Codebook Arrangement can be used in a coder of an input sound signal.

Transform-domain codebook in a CELP coder and decoder

A method and device for searching an algebraic codebook during encoding of a sound signal, wherein the algebraic codebook comprises a set of codevectors formed of a number of pulse positions and a number of pulses distributed over the pulse positions. In the algebraic codebook searching method and device, a reference signal for use in searching the algebraic codebook is calculated. In a first stage, a position of a first pulse is determined in relation with the reference signal and among the number of pulse positions. In each of a number of stages subsequent to the first stage, (a) an algebraic codebook gain is recomputed, (b) the reference signal is updated using the recomputed algebraic codebook gain and (c) a position of another pulse is determined in relation with the updated reference signal and among the number of pulse positions. A codevector of the algebraic codebook is computed using the positions of the pulses determined in the first and subsequent stages, wherein a number of the first and subsequent stages corresponds to the number of pulses in the codevectors of the algebraic codebook.

Method and device for fast algebraic codebook search in speech and audio coding

There is provided a transition mode device and method for use in a predictive-type sound signal codec for producing a transition mode excitation replacing an adaptive codebook excitation in a transition frame and/or a frame following the transition in the sound signal, comprising an input for receiving a codebook index and a transition mode codebook for generating a set of codevectors independent from past excitation. The transition mode codebook is responsive to the index for generating, in the transition frame and/or frame following the transition, one of the codevectors of the set corresponding to the transition mode excitation. There is also provided an encoding device and method and a decoding device and method using the above described transition mode device and method.

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Sherbrooke, Canada

Vaclav Eksler