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.
HIGH_STREAM_LAYER1
HIGH_STREAM_LAYER1:3
HIGH_STREAM_LAYER2
HIGH_STREAM_LAYER2:4
HIGH_STREAM_LAYER3
HIGH_STREAM_LAYER3:5
HIGH_STREAM_LAYER4
HIGH_STREAM_LAYER4:6
HIGH_STREAM_LAYER5
HIGH_STREAM_LAYER5:7
HIGH_STREAM_LAYER6
HIGH_STREAM_LAYER6:8
LOW_STREAM
LOW_STREAM:1
1: Automatically subscribe to the low-video stream under poor network conditions.
The stream fallback option. Set the stream fallback option when calling [setStreamFallbackOption]IAgoraRTCClient.setStreamFallbackOption.