I need a low bit rate stream camera with rather clear image, so I choose reolink product with H.265 feature, I baught RLC-820A. 
Firmware version: v3.1.0.956_22041501

I use vlc to check rtsp stream H.264 or H.265(rtsp://admin:password@192.168.0.157/h265Preview_01_main), I find only resolution 3840*2160 is H.265, other resolution(2560*1440,2304*1296) all be H.264.
But what I need is low bit rate stream, H.265 output only in most high resolution still output too high bit rate.

Why reolink camera not output H.265 stream when in low resolution?