I have a question about bitrates.
If I stream a 1080p stream at 3000kbps into a B, and the B gets 720p, 576p, 360p, 240p and 144p encoded streams from the O/T, then what are the bitrates of all the hls streams being served by the B?
If the B is configured to use profile presets, then the renditions will be encoded using the hardcoded bitrate for each of the presets. The link provided highlights the profile preset definitions including their bitrates.
The B can also be configured to use custom profiles with user defined bitrates for each rendition. See the transcoding options docs for details on how to configure B to use custom profiles.