Abstract: A method and apparatus for performing a active packet bundling in a VoIP (Voice over Internet Protocol) based on a measure of voice concealability of one or more speech packets to be transmitted. Voice concealability is a property of a speech packet which indicates the likelihood that a given speech segment will meet the “quasi-stationary” (QS) behavior assumed by conventional Packet Loss Concealment (PLC) algorithms used to compensate for transmission loss of speech packets. By ensuring that only well-concealed frames are delayed for bundling, it is more likely that the receiver will run the PLC algorithm when it is most effective (i.e., when it is likely to perform well at reconstructing the missing speech frame), rather than when it is more likely to be ineffective. This allows for a reduction in bandwidth while minimizing any potential negative impact on quality.

Abstract: A method and apparatus for handling network jitter in a Voice-over IP communications network using a virtual jitter buffer and time scale modification. A sequence of voice packets is received, where the sequence of voice packets may comprise a talk spurt, and the packets are stored in a jitter buffer having an initial playback latency of zero. Then, a number of the initial voice packets in the sequence are advantageously time-expanded and played out, thereby increasing the depth of the jitter buffer (and thus the amount of network jitter handled). Then, a number of subsequent voice packets are advantageously time-compressed and played out to return the jitter buffer depth to zero. In one embodiment, the sequence of voice packets comprises a talk spurt, and in another embodiment, the sequence of voice packets comprise those which are received during a cellular handoff.

Abstract: A method and apparatus for enhancing voice intelligibility for network communications of speech such as, for example, VoIP (Voice-Over-Internet-Protocol), in the presence of packets which arrive too late for normal playout. When a late speech packet is received by a speech decoder, that packet and, if necessary, one or more additional packets subsequent thereto, are played out over a shorter than normal duration so that the decoder can “catch up” with the encoder. Since a voice frame is usually decoded in several sub-frames—typically two or three—this shortened playout may be achieved, for example, by skipping one sub-frame from each frame to be shortened.