Abstract: An overflow problem of LSF quantization in G.729 Annex B speech encoding which may lead to non-assignment of a codebook index. Preferred embodiments fix the problem with default or limited random variable assignments or flagging the overflow and adjusting the frame encoding such as by limiting spectral components or changing quantization targets.

Abstract: ITU Recommendation G.729 Annex E teaches in the implementation of a fixed codebook search to determine the selected sample combination providing the minimal difference between the original input speech and the reconstructed speech after implementation of the codec. A large number of sample sets are processed and the difference between the original input signal and the reconstructed signal for each set is determined and stored in a register. Under certain conditions, the register can overflow resulting in invalid difference values. When such a condition occurs, the fixed codebook search cannot determine the sample combination providing the minimal mean square error between the weighted input speech and the weighted reconstructed speech. An initialization vector for the codvec vector is used to provide valid data which conforms to the G.729 Annex E specifications and minimizes changes to the G.729 source code while providing robust quality signal processing in the event of register overflow condition.

Abstract: A method of initializing an ITU Recommendation G.729 Annex B voice activity detection (VAD) device is disclosed, having the steps of (1) extracting a set of parameters from a signal that characterize the signal; (2) calculating an energy measure of the signal from the set of parameters; (3) comparing the energy measure with a reference value; (4) determining an initial value for an average of a noise characteristic of the signal; and (5) counting the number of times the energy measure equals or exceeds the reference level. Also disclosed is a method of converging an ITU Recommendation G.

Abstract: A method to reduce the amount of bandwidth used in the transmission of digitized voice packets is described. The method is used to reduce the number of transmitted packets by suspending transmission during periods of silence or when only noise is present. The system determines if a background noise update is warranted based on human auditory perception factors instead of an artificial limiter on excessive silence insertion descriptor packets. The system searches for characteristics in the perceptual changes of background noise instead of analyzing speech for improved audio compression. The invention weighs factors affecting the perception of sound including frequency masking, temporal masking, loudness perception based on tone, and auditory perception differential based on tone.

Abstract: ITU Recommendation G.729 Annex E teaches in the implementation of a fixed codebook search to determine the selected sample combination providing the minimal difference between the original input speech and the reconstructed speech after implementation of the codec. A large number of sample sets are processed and the difference between the original input signal and the reconstructed signal for each set is determined and stored in a register. Under certain conditions, the register can overflow resulting in invalid difference values. When such a condition occurs, the fixed codebook search cannot determine the sample combination providing the minimal mean square error between the weighted input speech and the weighted reconstructed speech. An initialization vector for the codvec vector is used to provide valid data which conforms to the G.729 Annex E specifications and minimizes changes to the G.729 source code while providing robust quality signal processing in the event of register overflow condition.

Abstract: An overflow problem of LSF quantization in G.729 Annex B speech encoding. Preferred embodiments fix the problem with default or limited random variable assignments or flagging the overflow and adjusting the frame encoding such as by limiting spectral components or changing quantization targets.

Abstract: A method of initializing an ITU Recommendation G.729 Annex B voice activity detection (VAD) device is disclosed, having the steps of (1) extracting a set of parameters from a signal that characterize the signal; (2) calculating an energy measure of the signal from the set of parameters; (3) comparing the energy measure with a reference value; (4) determining an initial value for an average of a noise characteristic of the signal; and (5) counting the number of times the energy measure equals or exceeds the reference level.