C20 - MCU Downspeeding doubt

[mario.romeropons]

Hi,
We have 3 C20 endpoints (all have High Definition and Natural presenter option keys) and a MCU 8510 with HD ports.

We don't understand the behaviour in one endpoint ("Juan Rejón")in diferent cases:

Case 1:
- Participants: Uriel, Juan Rejón, Tibidabo and MCU
- Maximum video size: Tx 4CIF Rx 4CIF (configured in MCU)
- IP Bandwith (configure on TMS when we schedule): 1,4 Mbps

No motion: In this case Juan Rejón decrease its bit rate. Also MCU when tx Juan Rejón flow to the others participants decrease its bit rate. Uriel and Tibidabo keep its bits rate.

Case 2:
- Participants: Uriel, Juan Rejón, Tibidabo and MCU
- Maximum video size: Tx MAX Rx MAX
- IP Bandwith (configure on TMS when we schedule): 1,4 Mbps

No motion: In this case Juan Rejón keeps its bit rate but MCU when tx Juan Rejón flow to the others participants decrease it. Uriel and Tibidabo keep its bits rate.

Case 3:
- Participants: Uriel, Juan Rejón, Tibidabo and MCU
- Maximum video size: Tx MAX Rx MAX
- IP Bandwith (configure on TMS when we schedule): 1,8 Mbps

No motion: Juan Rejón. Uriel and Tibidabo keep its bits rate.

We set a "cascade" layout (endpoint 1 viewed endpoint 2, endpoint 2 viewed endpoint 3, endpoint 3 viewed endpoint 1).
If there are movement, we don't have any downspeeding in all cases.
Anyone know why no motion could only affect Juan Rejón's bit rate in each case?

Regards.

[Patrick Pettit]

Hi Mario.  What is the SW version on your 8510? If three sites are in a conference and depending on the layout, lets say a 5+1 in this case, the one in the predominant pane, the +1, the MCU will raise the Rx BW from this site since this is the site everyone sees.  Since this site is the one in the +1 pane, what it sees is the other site which is also flowed up to its maximum bit rate.  The site in the smaller pane, which is predominant, the video Rx from this site is flow controlled since its not predominant.  Looking at a snapshot on the conference page will help much better to see what is being transmitted and received from the MCU and the C20's in this case, but what your describing here sounds like Video Rx Bit Rate Optimization may be coming into play which is now enabled by default on MCU 4.3 running in HD mode. 

If you can snapshot the conference page and list the layout being used, it may help in proving this. 

Thanks in advance.

VR

Patrick