Thank you for your inquiry about the Wowza ClearCaster product.
To answer your question, the encoding parameters are controlled by FaceBook through the API. For example, a 1080p stream would be sent at a bitrate around 8Mbps. The Wowza ClearCaster logic will adjust the bitrate on the fly based on network conditions.
For your reference, I am providing you with some useful links for the Wowza ClearCaster:
Product Description Page: https://www.wowza.com/products/clearcaster
Getting Started Guide: https://www.wowza.com/docs/wowza-clearcaster-getting-started
User Guide: https://www.wowza.com/docs/wowza-clearcaster-user-guide
You can also sign up for a free demo to see it in action and ask additional questions with one of our Wowza ClearCaster experts. http://info.wowza.com/clearcaster-free-demo
Technical Support Representative – Wowza ClearCaster