Issue Description：
A conference is held on a VP9000 series MCU that works in universal transfer mode and whose packet loss concealment (PLC) capability is set to SEC1.0. Participants in the conference include ViewPoint 8000 series endpoints, ViewPoint 9000 series endpoints, and TE Desktop&TE Mobile software clients. When a TE Desktop or TE Mobile software client views the video of a ViewPoint 8000 series endpoint or a ViewPoint 9000 series endpoint, a black screen is displayed.
Possbile reason：
In universal transfer mode, when a TE Desktop or TE Mobile software client views the video of a ViewPoint 8000 series endpoint or a ViewPoint 9000 series endpoint, if the ViewPoint 8000 series endpoint or ViewPoint 9000 series endpoint encodes media streams using SEC1.0, the MCU filters out only redundancy SEC1.0 packets without changing the encoding format of the media streams. The Desktop&TE Mobile software client does not support SEC1.0 and cannot parse SEC1.0 media streams. As a result, a black screen is displayed.
Solution :
Change the PLC capability.
On the MCU web interface, choose Settings > Conference and set Packet loss concealment to a value other than SEC1.0.
