3com Corporation

Gad Azriel

Haim Rochberger

Yackov Sfadya

Sarit Shani Natanson

An apparatus for and a method of audio recording in packet based telephony systems. Using the present invention, the equivalent of four audio channels are recorded utilizing only two recording channels. Each channel recorded comprises the stream of packets generated and transmitted by each endpoint to the other side. The RTP packets include the samples generated by the particular endpoint in addition to the timestamp of the samples received from the other side actually played by the endpoint. The recording device has knowledge of what was played at the other endpoint in order to accurately playback the audio samples generated by and received from the other endpoint. The recording device receives a packet stream containing the audio generated on each endpoint and the timestamp of the packet from the other side that was played on the endpoint. The recording device can reconstruct from this data the audio signal that was actually played on each endpoint.

Four channel audio recording in a packet based network

An apparatus for and a method of dynamically prioritizing packets over a packet based network. Packets are dynamically prioritized on the basis of their 'time to live' in the network as they travel from one network entity to another. Packets are assigned a priority in accordance with how 'old' or &lsquo;young&rsquo; they are. Packets with a relatively long time left to live are assigned lower priority then those with relatively little time left to live. A time to live (TTL) field is added to the packet as it travels from one network entity to another. The contents of the time to live (TTL) field represents how &lsquo;young&rsquo; or &lsquo;old&rsquo; the packet is and conveys the time left before the packet is no longer of any use. Each network entity that receives the packet with a TTL field, subtracts from it the time the packet spends passing through that entity. The field decreases as it hops from network entity to entity until it reaches its destination or is discarded.

Method of dynamic prioritization of time sensitive packets over a packet based network

An apparatus for and a method of remote echo cancellation in a packet based telephony system. Echo cancellation algorithms normally performed on the local end of a connection, are performed instead by the remote end of the connection. Alternatively, the echo cancellation algorithms are performed for both the local and remote ends of a connection on a remote device. In the former case, the remote endpoint estimates the echo function of the local endpoint using audio and timing synchronization data corresponding to the actual audio played at the local endpoint. Using this information, the remote endpoint is able to accurately perform echo cancellation.

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Holon, Israel

Gad Azriel