This article relates to the Cisco TelePresence MCU 4203, Cisco TelePresence MCU MSE 8420, Cisco TelePresence MCU 4505 and Cisco TelePresence MCU MSE 8510 products.
Q. Why does my endpoint show H.264 for transmit and H.263 for receive when connected to a Codian MCU?
A. The Codian MCU will change the resolution and the codec being sent to an endpoint to try to produce the best image based on the capabilities of the endpoint being used. In particular there are several endpoints which can support H.264 at CIF resolutions, but at 4CIF they can only support H.263 - and often only at 15 frames per second.
For any given view that an endpoint is seeing, the MCU will dynamically change the resolution and the codec to optimize the video quality. For example, switching from a continuous presence layout to a full screen voice-activated layout will often cause the MCU to switch between sending H.263 at 4CIF to sending H.264 at CIF.
For more information about how the MCU chooses between available resolutions to send to an endpoint, see the Related articles below.