Back to results
US 6,691,092 B1Granted
Voicing measure as an estimate of signal periodicity for a frequency domain interpolative speech codec system
AssigneeHughes Electronics Corporation
InventorsBangalore R. Udaya Bhaskar, Srinivas Nandkumar, Kumar Swaminathan, Gaguk Zakaria
Life of this patent
Estimating the term…
Abstract
A system determines a voicing measure as a measure of the degree of signal periodicity and uses the determined voicing measure to quantize the spectral magnitude of the slowly evolving waveform (SEW) and the modeling of the SEW and rapidly evolving waveform (REW) phase spectra.
Claims12
A frequency domain interpolative coding system for low bit-rate coding of speech signals, comprising:
- a linear prediction (LP) front end, responsive to an input signal, providing LP parameters which are quantized and encoded over predetermined intervals and used to compute a LP residual;
- an open loop pitch estimator, responsive to said LP residual signal, a pitch quantizer, and a pitch interpolator yielding a pitch contour within the predetermined interval;
- a voice activity detector (VAD) mechanism responsive to said LP parameters and open loop pitch, generating a VAD flag for every predetermined interval;
- a signal processor responsive to said LP residual signal and the pitch contour for extracting a prototype waveform (PW) for a number of equal sub-intervals within the predetermined interval;
- and
- said signal processor computing a PW gain for generating a normalized PW for each sub-interval and a PW gain vector for the predetermined interval;
- a separation of the normalized PW into a slowly evolving waveform (SEW) component and a rapidly evolving waveform (REW) component using a low-pass filter along every pitch harmonic track;
- a representation of one or more of the components of the normalized PW in spectral magnitude-phase form;
- and a characterization of the degree of periodicity of the input signal by a voicing measure, derived from certain parameters that are correlated to signal periodicity and computed from the input signal, PW, SEW and REW over the predetermined interval.
6 more elements
A frequency domain interpolative coding system for low bit-rate coding of speech signals, comprising:
- a linear prediction (LP) front end responsive to an input signal, providing LP parameters which are quantized and encoded over predetermined intervals and used to compute a LP residual signal;
- an open loop pitch estimator responsive to said LP residual signal, a pitch quantizer, and a pitch interpolator yielding a pitch contour within the predetermined interval;
- a signal processor responsive to said LP residual signal and the pitch contour for extracting a prototype waveform (PW) for a number of equal sub-intervals within the predetermined interval;
- and
- said signal processor computing a PW gain for generating a normalized PW for each sub-interval and a PW gain vector for the predetermined interval;
- a separation of the normalized PW into a slowly evolving waveform (SEW) component and a rapidly evolving waveform (REW) component using a low pass filter along every pitch harmonic track;
- a characterization of the degree of periodicity of the input signal by a voicing measure, derived from certain parameters that are correlated to signal periodicity and computed from the input signal, PW, SEW and REW over the predetermined interval;
- a representation of the SEW component in spectral magnitude-phase form and transmission of only the spectral magnitude information of the SEW component;
- and a reconstruction of the SEW and REW phase components at the decoder using the received SEW and REW magnitude components, the voicing measure, and pitch frequency contour information.
6 more elements
Dependencies are inferred from the claim text.