Abstract: Conferencing data is reliably delivered to computer systems participating in a hierarchically arranged multi-cast conferencing session. When a child computer system does not receive a multi-cast packet (e.g., an IP multi-cast packet), the child computer system sends a negative acknowledgment to a parent computer system. In response, the parent computer system re-transmits conferencing data that was contained in the multi-cast packet to the child computer system. Conferencing data can be re-transmitted to the child computer system via uni-cast (e.g., TCP). Accordingly, conferencing data that is not received or that is damaged via multi-cast can be repaired via uni-cast. Computer systems can join an existing multi-cast conference session without having to communicate with the root computer system. The root computer system adjusts a multi-cast send rate to compensate for changed network conditions.

Abstract: Disclosed are methods that enable communications to be established regardless of the presence of communications blockers, e.g., firewalls and NATs, in the path between two computing devices. Two devices each establish communications with a rendezvous service. Through the service, the devices signal each other to set up direct, peer-to-peer communications between themselves. If the devices fail to establish direct communications, then they invoke a relay service that provides the illusion of direct communications. In another aspect, an originating device attempts to establish communications with a recipient, using an address and port number associated with the recipient. If that attempts fails, possibly because a firewall is blocking communications, then the originating device retries using a port normally held open by firewalls. If this attempt also fails, then the originating device invokes the services of a proxy to negotiate a port acceptable for use by the recipient and by any intervening firewalls.

Abstract: Conferencing data is reliably delivered to computer systems participating in a hierarchically arranged multi-cast conferencing session. When a child computer system does not receive a multi-cast packet (e.g., an IP multi-cast packet), the child computer system sends a negative acknowledgment to a parent computer system. In response, the parent computer system re-transmits conferencing data that was contained in the multi-cast packet to the child computer system. Conferencing data can be re-transmitted to the child computer system via uni-cast (e.g., TCP). Accordingly, conferencing data that is not received or that is damaged via multi-cast can be repaired via uni-cast. Computer systems can join an existing multi-cast conference session without having to communicate with the root computer system. The root computer system adjusts a multi-cast send rate to compensate for changed network conditions.

Abstract: In order to minimize the delay of the video images viewed by a network conference attendee, an intelligent buffering process (IB process) selectively discards video frames from at least one point, and in an embodiment, many network points, such as at “in” and/or “out” buffers of clients, servers, routers, etc. Packets of video frame data arrive at a buffer, which can fill to a predetermined limit if the packets cannot be forwarded due to delays or slow connections. To forward the most current video images, old frames in the buffer are discarded rather than forwarded. In a particular embodiment, when the buffer is full, the next arriving delta frame packet is discarded. To avoid distortion, each subsequent delta frame is discarded until a new key frame eventually arrives. If the buffer is still full when the key frame arrives, the buffer is purged and the new key frame is added.

Abstract: A method and system to generate a grammar adapted for use by a speech recognizer includes receiving a representation of an alphanumeric expression. For instance, the representation can take the form of a regular expression or a mask. The grammar is generated based on the representation.

Abstract: A device of exact standard dimensions for quickly and efficiently placing furring straps, comprising an elongated body having an abutment shoulder on one end and a cradle on a second end with a handle long enough to enable reaching ceilings.