Polycom, Inc.

David N Hein

Stephen C Botzko

John Paul Spearman

Richard Flott, Jr

Alain Elon Nimri

Michael Kenoyer

Guruprasad Subbarao

Larry Roundy

Devices and techniques for overcoming lost packets and avoiding congestion when conducting media conferences over packet switched networks are described herein. To avoid the problem of lost packets, redundant information is inserted into the media stream that permits the receiver to reconstruct any lost packets from the redundant information. Congestion avoidance techniques include adjusting the bitrate of the media stream to find the highest bitrate that can be supported without packet loss due to congestion. When increasing the bitrate to a higher rate, the additional bits can come from the redundant information used for lost packet recovery so that any lost packets caused by network congestion will not adversely affect the bitstream.

System and method for lost packet recovery with congestion avoidance

Assigning inbound ringing ISDN channels to a particular endpoint's call uses a framing listening technique to distinguish between H.221 framing, master bonding channel framing and slave bonding channel framing. If the channel is receiving Master Bonding Channel framing, the MCU detects that this is a new call from a unique far endpoint and may then begin a process to address this new call. If the channel is receiving Slave Bonding Channel framing, the MCU then transmits a multi-frame pattern and looks for a Physical Video Unit Identifier the MCU sent to this far end via the Master Channel upon initial negotiation. If the channel is receiving H.221 framing, a H.243 terminal address assigned using a Terminal Indicate Assignment (TIA) message in the initial channel is used. The far endpoint may then send this address in its additional channels through the use of a Terminal Indicate Additional Channel X (TIX) message. The MCU may associate an incoming channel to the correct call by examining the address sent by the far endpoint in the TIX message. In the case of simultaneous calls according to the H.323 protocol, the process retains the incoming H.323 call in the current state (i.e., Alerting/Incoming Ringing State), and waits until the current call progresses to a state Call Connected, after which the incoming call may be allowed to be answered and transitioned to its Call Connected state. This may be done without hanging up the incoming call with a busy indication.

Method and apparatus for simultaneous incoming digital call processing using ISDN bonding channels

An automatic switching system and method for determining and effecting an optimal video display mode based on the interaction among participants in a conference or discussion is disclosed. The system includes a timer which continuously monitors the duration of signals received from each of a number of endpoints. The system further includes a signal switching processor which compares the signal durations to predefined parameters which define various display mode switching thresholds. The system reacts to the conversational interaction of endpoint participants by automatically switching the display mode of all endpoints between single-window, single speaker presentation mode, and multiple-window, multiple speaker discussion mode.

Video display mode automatic switching system and method

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Pflugerville, TX, United States of America

David N Hein