Abstract: A multiply and accumulate engine may implement a digital filter. In some embodiments, the number of coefficients that are stored may be equal to only half of the number of filter taps that are implemented. This may be done by doing multiplications operand by operand within two data registers in a first direction and then shifting directions so that the first operand in a first register is multiplied by the last operand in another register. In some embodiments, the multiply and accumulate engine may be implemented as a two cycle engine wherein in the first stage, multiply and accumulate operations are implemented and then stored into a register. In a second stage and a second cycle, the results stored in the register are further accumulated.

Abstract: A system for validating codec software includes sending to a validation server duplicates of the real-time endpoint encoder and decoder input/output datas. A comparator of the validation server compares the encoder output data to a pre-tested reference code and the decoder output data to a pre-tested reference code. The process continues for as long as the endpoints are in the live audio session or until the validation server terminates collection of data. In one embodiment, the comparator may send an error message to an alert device if a mismatch between the datas is encountered. The system may further include a speech quality evaluator for determining a real-time QoS of the networked speech. The evaluator collects the encoder output data of a first endpoint and the same data after traveling through the data network and presented as the decoder input data of a second endpoint to determine the QoS.

Abstract: A system and method for audio multicast includes a flexible number of active and passive conferencing endpoints in packet communication with a server. The server creates a mixed audio stream from the received audio packets from the active endpoints. The server multicasts the mixed audio to all the conferencing endpoints. The endpoints determine if the received mixed audio includes any self-generated audio by comparing the received packet to a sample packet of self-generated audio stored prior to transmission to the server. The endpoint encodes and decodes its own audio twice to match the transformations that occurred for the endpoint's contribution to the mixed audio. If a match is present, the endpoint removes the self-generated audio from the mixed audio and plays the conference audio.

Abstract: A system and method for audio multicast includes a flexible number of active and passive conferencing endpoints in packet communication with a server. The server creates a mixed audio stream from the received audio packets from the active endpoints. The server multicasts the mixed audio to all the conferencing endpoints. The endpoints determine if the received mixed audio includes any self-generated audio by comparing the received packet to a sample packet of self-generated audio stored prior to transmission to the server. If a match is present, the endpoint removes the self-generated audio from the mixed audio and plays the conference audio.