Abstract: A method for preventing the loss of information within a speech frame is described. A first speech frame to be encoded is selected. A determination is made as to whether or not a second speech frame is a critical speech frame based on the information within the second speech frame and one or more adjacent speech frames. At least a part of an encoded version of the second speech frame is created according to a selected forward error correction (FEC) mode if the second speech frame is a critical speech frame. The first speech frame and the at least a part of the encoded version of the second speech frame are transmitted.

Abstract: In one embodiment, a method of generating a highband excitation signal includes generating a spectrally extended signal by extending the spectrum of a signal that is based on an encoded lowband excitation signal; and performing anti-sparseness filtering of a signal that is based on the encoded lowband excitation signal. In this method, the highband excitation signal is based on the spectrally extended signal, and the highband excitation signal is based on a result of the anti-sparseness filtering.

Abstract: Adaptive De-Jitter Buffer for Voice over IP (VoIP) for packet switch communications. The de-jitter buffer methods and apparatus presented avoid playback of underflows while balancing end-to-end delay. In one example, the de-jitter buffer is recalculated at the beginning of each talkspurt. In another example, talkspurt packets are compressed upon receipt of all remaining packets.

Abstract: A method for dimming a first packet associated with a first bit rate to a second packet associated with a second bit rate is described. A first packet is received. The first packet is analyzed to determine a first bit rate associated with the first packet. Bits associated with at least one parameter are discarded from the first packet. Remaining bits associated with one or more parameters and a special identifier are packed into a second packet associated with a second bit rate. The second packet is transmitted.

Abstract: In one embodiment, a method of generating a highband excitation signal includes harmonically extending the spectrum of a signal that is based on a lowband excitation signal; calculating a time-domain envelope of a signal that is based on the lowband excitation signal; and modulating a noise signal according to the time-domain envelope. The method also includes combining (A) a harmonically extended signal based on a result of the harmonically extending and (B) a modulated noise signal based on a result of the modulating. In this method, the highband excitation signal is based on a result of the combining.

Abstract: In one embodiment, a highband burst suppressor includes a first burst detector configured to detect bursts in a lowband speech signal, and a second burst detector configured to detect bursts in a corresponding highband speech signal. The lowband and highband speech signals may be different (possibly overlapping) frequency regions of a wideband speech signal. The highband burst suppressor also includes an attenuation control signal calculator configured to calculate an attenuation control signal according to a difference between outputs of the first and second burst detectors. A gain control element is configured to apply the attenuation control signal to the highband speech signal. In one example, the attenuation control signal indicates an attenuation when a burst is found in the highband speech signal but is absent from a corresponding region in time of the lowband speech signal.

Abstract: A system and method for detection of rate determination algorithm errors in variable rate communications system receivers. The disclosed embodiments prevent rate determination algorithm errors from causing audible artifacts such as screeches or beeps. The disclosed system and method detects frames with incorrectly determined data rates and performs frame erasure processing and/or memory state clean up to prevent propagation of distortion across multiple frames. Frames with incorrectly determined data rates are detected by checking illegal rate transitions, reserved bits, validating unused filter type bit combinations and analyzing relationships between fixed code-book gains and linear prediction coefficient gains.

Abstract: A method of communicating speech comprising time-warping a residual low band speech signal to an expanded or compressed version of the residual low band speech signal, time-warping a high band speech signal to an expanded or compressed version of the high band speech signal, and merging the time-warped low band and high band speech signals to give an entire time-warped speech signal. In the low band, the residual low band speech signal is synthesized after time-warping of the residual low band signal while in the high band, an unwarped high band signal is synthesized before time-warping of the high band speech signal. The method may further comprise classifying speech segments and encoding the speech segments. The encoding of the speech segments may be one of code-excited linear prediction, noise-excited linear prediction or ? frame (silence) coding.

Abstract: A wideband speech encoder according to one embodiment includes a lowband encoder and a highband encoder. The lowband encoder is configured to encode a lowband portion of a wideband speech signal as a set of filter parameters and an encoded excitation signal. The highband encoder is configured to calculate values for coding parameters that specify a spectral envelope and a temporal envelope of a highband portion of the wideband speech signal. The temporal envelope is based on a highband excitation signal that is derived from the encoded excitation signal. In one such example, the temporal envelope is based on a difference in levels between the highband portion and a synthesized highband signal, wherein the synthesized highband signal is generated according to the highband excitation signal and a set of highband filter parameters.

Abstract: A method for including an identifier with a packet associated with a speech signal is described. A signal is received. The signal is partitioned into a plurality of frames. A frame of the signal is encoded into a packet. A determination is made if the packet is encoded as a wideband packet or a narrowband packet. An identifier is packed in the packet based on the determination. The packet is transmitted. At least two illegal values are provided from an N-bit parameter, wherein at least one bit from the N-bit parameter is used to carry information. A number of bits from the N-bit parameter that are used to carry information is equal to log2(X), wherein X is the number of illegal values provided from the N-bit parameter.

Abstract: Systems and methods for adapting a de-jitter buffer to conform to air link conditions. An air link characteristic may be detected before that characteristic begins to affect packet delivery, such as by slowing or speeding delivery delay at a subscriber station. A receiver-side de-jitter buffer, which adds delay to received packets, may adaptively adjust its size based upon the detected air link characteristic, such that the de-jitter buffer is appropriately sized for anticipated data packets before they are received at the subscriber station.

Abstract: In one embodiment, a method of signal processing including includes encoding a low-frequency portion of a speech signal into at least an encoded narrowband excitation signal and a plurality of narrowband filter parameters; and generating a highband excitation signal based on a narrowband excitation signal. The encoded narrowband excitation signal includes a time warping, and the method includes applying a time shift to a high-frequency portion of the speech signal based on the information related to the time warping. The method also includes encoding the time-shifted high-frequency portion of the speech signal into at least one (A) a plurality of highband filter parameters and (B) a plurality of high band gain factors.

Abstract: A quantizer according to an embodiment is configured to quantize a smoothed value of an input value (e.g., a vector of line spectral frequencies) to produce a corresponding output value, where the smoothed value is based on a scale factor and a quantization error of a previous output value.

Abstract: A variable rate vocoder is configured to encode speech signals with a plurality of encoding rates and to change from a first encoding rate to a second encoding rate according to a received signal indicating reverse link load.