Abstract: A method for executing a video conference is provided that includes receiving one or more audio streams associated with a video conference from one or more end points and determining an active speaker associated with one of the end points. Audio information associated with the active speaker may be received at one or more media switches. One or more video streams may be suppressed except for a selected video stream associated with the active speaker, the selected video stream propagating to one or more of the media switches during the video conference. The selected video stream may be replicated such that it may be communicated to one or more of the end points associated with a selected one of the media switches.

Abstract: A method, an apparatus and a medium encoded with instructions for providing layout selection, participant selection, and/or participant-to-participant far end camera control of the selected participant for use in a continuous presence multipoint videoconference. The method includes receiving one or more far end camera control messages over a packet network from a first participant of a multipoint videoconference; maintaining an indication of a far end camera control mode for the first participant, the mode being one of a set of modes; and depending on the far end camera control mode and on controls possible, carrying out a control according to one ore more the camera control messages.

Abstract: A method, an apparatus and a medium encoded with instructions for providing layout selection, participant selection, and/or participant-to-participant far end camera control of the selected participant for use in a continuous presence multipoint videoconference. The method includes receiving one or more far end camera control messages over a packet network from a first participant of a multipoint videoconference; maintaining an indication of a far end camera control mode for the first participant, the mode being one of a set of modes; and depending on the far end camera control mode and on controls possible, carrying out a control according to one ore more the camera control messages.

Abstract: A method, an apparatus and a medium encoded with instructions for providing layout selection, participant selection, and/or participant-to-participant far end camera control of the selected participant for use in a continuous presence multipoint videoconference. The method includes receiving one or more far end camera control messages over a packet network from a first participant of a multipoint videoconference; maintaining an indication of a far end camera control mode for the first participant, the mode being one of a set of modes; and depending on the far end camera control mode and on controls possible, carrying out a control according to one ore more the camera control messages.

Abstract: Marking a keyframe of a media stream in a communication system involves one or more entry media switches in communication with one or more endpoints. An entry media switch receives a media stream from an endpoint, where the media stream comprises a sequence of packets with a keyframe. The keyframe is detected and marked with a keyframe indicator. The keyframe indicator is operable to notify a downstream device of the keyframe. An output media stream is outputted.

Abstract: Synchronizing audio and video streams in packet-based networks requires synchronization of packet timestamps. The present invention provides such synchronization without resort to a network time standard. In one embodiment of the present invention, pairs of timestamp synchronized signals, such as audio and video signals, not having a common timestamp clock are mixed. One of the signals, for example, the audio signals, is mixed first while preserving the original audio timestamps. The preserved timestamp information is then used to synchronize the timestamps of the unmixed signals, in this example the video signals, to provide synchronization of all signals. In another embodiment, the present invention uses packets containing calibration of timestamps to reduce jitter. The present invention also includes specifications for a packet for transmitting timestamp information.

Abstract: Providing a conference call includes establishing a bidirectional first class stream for each of a set of first class endpoints. A second class stream is established for each of a set of second class endpoints. Mixed streams are generated using the bidirectional first class streams, and one or more mixed streams are broadcasted to the set of second class endpoints. A particular second class endpoint is determined to have a right to have its stream included in the mixed streams. The second class stream for the particular second class endpoint is mapped to a bidirectional second class stream for the particular second class endpoint. Next mixed streams are generated using the bidirectional second class stream.

Abstract: A method for executing a video conference is provided that includes receiving one or more audio streams associated with a video conference from one or more end points and determining an active speaker associated with one of the end points. Audio information associated with the active speaker may be received at one or more media switches. One or more video streams may be suppressed except for a selected video stream associated with the active speaker, the selected video stream propagating to one or more of the media switches during the video conference. The selected video stream may be replicated such that it may be communicated to one or more of the end points associated with a selected one of the media switches.

Abstract: A method and an apparatus for providing layout selection, participant selection, and/or participant-to-participant far end camera control of the selected participant for use in a continuous presence multipoint videoconference. The method includes receiving an FECC message of a set of FECC messages over a packet network from a first participant, the first participant having a set of FEEC modes and being in one of the FECC modes. The method further includes maintaining knowledge of the mode of the first participant and interpreting the received FECC message according to the FECC mode of the first participant.

Abstract: Marking a keyframe of a media stream in a communication system involves one or more entry media switches in communication with one or more endpoints. An entry media switch receives a media stream from an endpoint, where the media stream comprises a sequence of packets with a keyframe. The keyframe is detected and marked with a keyframe indicator. The keyframe indicator is operable to notify a downstream device of the keyframe. An output media stream is outputted.

Abstract: An audio mixer on a first device receives one or more incoming audio streams. Each of the one or more incoming audio streams has an associated timestamp. The audio mixer generates a mixed audio stream from the one or more incoming audio streams. The audio mixer determines differences in the time base of each of the one or more incoming audio streams and the time base for the mixed audio stream. The audio mixer generates mapping parameters associated with the determined differences and transforms the timestamp of each of the one or more incoming audio streams to a corresponding output timestamp associated with the mixed audio stream according to the mapping parameters. the mapping parameters are provided to a video mixer for similar processing and transformation such that the mixed audio stream is in synchronization with a mixed video stream.

Abstract: A method for executing a video conference is provided that includes receiving one or more audio streams associated with a video conference from one or more end points and determining an active speaker associated with one of the end points. Audio information associated with the active speaker may be received at one or more media switches. One or more video streams may be suppressed except for a selected video stream associated with the active speaker, the selected video stream propagating to one or more of the media switches during the video conference. The selected video stream may be replicated such that it may be communicated to one or more of the end points associated with a selected one of the media switches.

Abstract: A physical layer controller for use in a data transmission network is disclosed which includes an automatic scrubbing arrangement that is activated upon the occurrence of a physical layer controller reconfiguration. The transmitter output port as well as each channel output of the physical layer controller has an output dirty flag associated therewith. Similarly, the input port as well as each channel input has an associated input dirty flag. A scrubbing arrangement automatically scrubs certain outputs after a configuration change. More specifically, in the absence of a blocking condition after a configuration change, the scrubbing arrangement will automatically scrub each output which has a new source and one of: 1) its associated output dirty flag is set to a first level; and 2) it is connected to an new source which has its associated input dirty flag set to a first level. In a method aspect, output dirty flags are set for each output that has the potential to transmits a data frame.

Abstract: A controllable physical connection management (PCM) pseudo code user interface is disclosed for use in the physical layer controller of a station or concentrator that is capable of insertion into a data transmission network that is capable of operating substantially in accordance with the FDDI protocol. In one aspect of the invention, the interface permits the user to direct the PCM state machine to pause after entering the Next state after the transmission of any pseudo code signalling bit. In another aspect of the invention, the interface permits a user to load a hardware register with the pseudo code signalling information to be transmitted before the signalling begins. However, Complete control of the pseudo code signalling is retained by the user during the signalling process to permit midstream changes in the pseudo code sequence to protect against communications with unexpected neighboring port configurations and to permit custom pseudo code signalling sequences.

Abstract: A controllable configuration management (CFM) state machine user interface is disclosed for use in the physical layer controller of a station or concentrator capable or insertion into a data transmission network that is capable of operating substantially in accordance with the FDDI protocol. In one aspect of the invention, the physical layer controller includes a null configuration register, a join configuration register and a loop configuration register. The null configuration register is capable of storing information indicative of a desired configuration of the physical layer controller when the CFM state machine is in a null configuration. Similarly, the join and loop configuration register are capable of storing information indicative of desired configurations when the CFM state machine is in the join and loop configurations respectively.

Abstract: A controllable physical connection management (PCM) state machine user interface is described for use in the physical layer controller of a station or concentrator capable of insertion into a data transmission network that operates substantially in accordance with the FDDI protocol. In one aspect of the invention, the interface permits the user to direct the PCM state machine to pause after entering a particular state during the initial connection management sequence. In another aspect of the invention, the interface permits a user to force a state transition by writing the desired new state into a state register. These user interface features allow the state transitions to be controlled by the user and therefore possibly changed. In a preferred embodiment, the user initiated state transition can occur while the PCM state machine is paused.