2: Subscribe to the low-quality video stream when the network conditions worsen, and subscribe to audio only when the conditions become too poor to support video transmission.
DISABLE
DISABLE: = 0
0: Disable the fallback.
LOW_STREAM
LOW_STREAM: = 1
1: (Default) Automatically subscribe to the low-video stream under poor network conditions.
The stream fallback option. Set the stream fallback option when calling setStreamFallbackOption.