If you stream in multiple bitrates via Livestream Producer or Livestream Studio, or streams via RTMP through a third-party encoder, viewers will see the ability to adjust which quality they watch in the bottom right corner of the live player. By default, Auto is selected.
Auto will allow the player to automatically adapt and adjust which of the available qualities the viewer will see the stream in based on their available connection speed. The player will always attempt to play the highest quality stream possible for that viewer's connection.
Viewers can choose to manually adjust the quality of the stream they're viewing by clicking the gearwheel icon, and then selecting which of the available qualities they want to watch the stream. The player will not adapt to changing connection speeds if viewers do this, so if their connection slows down, they may experience buffering and would have to switch to a lower quality manually to improve playback.
This option is only available on desktop browsers. Other viewing apps (mobile app, Roku, tvOS, etc.) will always adapt to the best possible quality during multi-bitrate streams.
If you are streaming via a Mevo, a Broadcaster, the Livestream mobile app, or simply chose a single bitrate in Producer or Studio, then your viewers will only see your stream in that single quality. Livestream cannot transcode these streams into multiple bitrates and thus the player will not adapt.