Sharing Content During Conferences
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When a new endpoint with lower content capabilities joins while content is shared, content sharing
parameters are downgraded to this endpoint capabilities:
● If downgrade affects the protocol (from H.264 to H.263) or profile type (from high to base), content
sharing is terminated, protocol automatically downgrades to H.263, or in H.264, profile downgrades
to base profile, and content sharing should be manually resumed.
● If downgrade affects only the content rate, resolution or frame rate (in H.264), the relevant content
parameters automatically downgrade during content sharing.
Once this endpoint leaves the conference during content sharing, no change occurs in the content
parameters.
Highest Common Calculation Depending on Content Settings
For Graphics, Hi-res Graphics and Live Video (see Content Settings), the highest common content is
calculated for the conference each time an endpoint connects. Highest Common content bit rate is
calculated using:
● For H.263 - Line rate
● For H.264 - Line rate, resolution, and frame rate.
Therefore, when endpoints with lower capabilities connect to an ongoing conference, content parameters
are re-calculated and decreased accordingly.
During content sharing, the MCU does not permit endpoints to increase their content bit rate, only their
content resolution.
For more information, see H.264 Highest Common Content Rates Tables. For information on minimum
content rates as determined by system flags, see H.264 HD System Flags.
Fixed Rate
In this method the content rate is fixed, and endpoints not supporting this rate do not receive content over
the content channel. Endpoints whose capabilities are too low, can only view content over the people video
layout (see Sending Content to Legacy Endpoints).
For H.263 cascaded conferences, the MCU automatically uses a fixed rate (once a cascaded link is
detected) according to the content rates described in Highest Common and Fixed Content Bit Rate
Allocation for H.263.
For H.264 cascaded conferences, the MCU uses a fixed rate according to the content rates described in
H.264 Cascade Optimized (Fixed) Content Rates Tables, and the high/base profile configured by the user.
Multiple Content Resolutions
This method must be used for cascaded conferences.
This method is often related to as content transcoding.
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