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Cisco TelePresence MCU 4200 Series

Endpoint reports different resolution for transmit/receive when connected to an MCU/IP VCR

Why does my endpoint report a different resolution for transmit and receive when connected to a Cisco TelePresence MCU/IP VCR?

The Cisco TelePresence MCU and IP VCR can receive a number of resolutions from endpoints in order to allow each endpoint to send the resolution that is optimal for it. For example, this can depend on the resolution of the endpoint's camera or a user preference setting on the endpoint. Typically, a High Definition endpoint would have a high definition camera allowing it to send 720p (1280x720), whereas an older endpoint may be restricted to CIF (288x352) or SIF (240x352).

The resolution that the MCU sends back to the endpoint is likely to vary during a conference as the participant changes his or her layout view, or the pane arrangement changes because the active speaker change.

  • If the endpoint is displaying the current speaker full screen (voice activated mode), then the resolution will be that of the speaker's camera (or as close to it as the endpoint can display). This may allow an endpoint to transmit CIF and receive SIF, for example.
  • If the endpoint is viewing a continuous presence layout, then the MCU may choose to transmit higher resolutions such as 4CIF, VGA or even 720p (High Definition). This may be necessary to preserve the video quality of individual panes; for example, to avoid scaling down a video stream received from a High Definition endpoint.

When the MCU has the choice of resolutions to send to an endpoint, the maximum frame rate may be different for each resolution. The Motion/sharpness tradeoff setting is used in these cases to allow the MCU to make a choice based on administrator preference. For example, you may choose to always send a high resolution at a lower frame rate, rather than preserving frame rate at the cost of sending a lower resolution. (For information about configuring the motion/sharpness tradeoff setting, see the online help.)

The maximum usable resolution for any given endpoint is also dependent on the call bit rate: it is not useful to send very high resolutions at low bit rates.

The IP VCR records video at the resolution that the endpoint sends. The Motion/sharpness tradeoff setting only affects the resolution used for playing back an existing recording to an endpoint. (For information about configuring the motion/sharpness tradeoff setting, see the online help.)

This article applies to the following products:

  • Cisco TelePresence IP VCR 2200 / MSE VCR blade
  • Cisco TelePresence MCU 4200 / MSE 8420
  • Cisco TelePresence MCU 4500
  • Cisco TelePresence MSE 8510 blade

April 18th, 2011 TAA_KB_61