Some Recording Parameters may need Motion to be supported by the Camera. Motion + Low Quality Always recording requires Dual-Streaming to be supported by Camera.
If Dual-Streaming is supported, the second stream settings are set automatically based on the main recording settings:
•2 to 7 FPS
•320p to 480p
Not only is the second stream used for recording, it is also used for Software Motion Detection and bandwidth and CPU saving during playback. See "Setting up Motion Mask and Motion Sensitivity" and "CPU and Bandwidth Saving during Playback (RADASS)".
If primary stream is 480p or less, it can be used for Software Motion Detection as well.