Maintenance Manual

channel to the MCU and contributes a video stream, such as that supplied by a second camera or an attached
PC.
Because there can be at most one content channel source, the H.323 endpoint needs to make a request to
the MCU, and have that request accepted, before actual content channel contribution can start. If the
conference already has an active content channel (for example, another endpoint is contributing H.239
video), the new request will be rejected by the MCU - it will be necessary to wait for the active contributor to
cease sending H.239 video before the new endpoint is able to start. However, if you have enabled Automatic
content handover (on the Settings > Content page), the new request will be granted automatically.
■ BFCP video channel
BFCP (Binary Floor Control Protocol) is a protocol that allows for an additional video channel (known as the
content channel) alongside the main video channel in a video-conferencing call that uses SIP. A SIP
conference participant opens a BFCP channel to the MCU and contributes a video stream, such as that
supplied by a second camera or an attached PC.
Because there can be at most one content channel source, the SIP endpoint needs to make a request to the
MCU, and have that request accepted, before actual content channel contribution can start. If the conference
already has an active content channel (for example, another endpoint is contributing content video), the new
request will be rejected by the MCU - it will be necessary to wait for the active contributor to cease sending
content video before the new endpoint is able to start. However, if you have enabled Automatic content
handover (on the Settings > Content page), the new request will be granted automatically.
Note that the transmission of SIP content using BFCP is not supported on encrypted calls in any content
modes. To allow content to be transmitted over SIP calls in a separate channel from main video, disable
encryption on the MCU or on the target endpoint.
■ VNC connection
A VNC connection is one where the MCU has made a connection to a remote device (normally a desktop PC)
and is receiving a video stream from that device; this is typically used for including a slide-based presentation
in a conference.
If Automatic content handling is disabled, and a conference is configured with content channel support,
when a VNC "participant" is added to that conference, the MCU will attempt to use the VNC video as the
content channel. This is normally the desired behavior; however, there are a couple of caveats:
— If there is a video conferencing endpoint actively contributing content video then it will not be possible to
immediately switch over to using the VNC video instead - the switch over will occur when the participant
closes his content channel.
— With more than one active VNC connection in a conference, the first will be used as the content channel
source, and subsequent connections will be shown in main video layout panes, just as if the conference
had no content channel facility. If the currently active VNC connection is either disconnected or its use as
the content channel disabled, another VNC video stream will start to be used as the content channel.
If Automatic content handling is enabled:
— If there is a video conferencing endpoint actively contributing content video, the MCU will automatically
switch to using the VNC video as the content channel.
— If there is already an active VNC connection in a conference, a second VNC connection will automatically
replace the first as the content channel (rather than appearing as a pane in the main video).
■ Participant main video
It is also possible for the MCU to use a endpoint's main video channel as the conference's content channel
(when in Transcoded or Hybrid content modes).
This has the same caveats as the use of a VNC connection for the content channel, as described above.
■ Video markup
Whichever of the content channel sources mentioned above is active, the MCU provides the facility for users
to add markup to the video channel. This markup consists of an additional video overlay on to which graphics
may be drawn and text added; content channel viewers see the content channel source video plus this
overlay. The overlay can be cleared later leaving the source video unaltered.
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