Reolink cameras only support MP4 video encapsulation format.
Applies to: Which Reolink Products Support CGI_RTSP_ONVIF
Regarding the video compression format: for Reolink 8MP cameras, the compression type of the RTSP main-stream is H.265 and the compression type of the RTSP sub-stream is H.264. For Reolink 2MP, 4MP, and 5MP cameras, the compression type of RTSP video is H264, some models support changing format mode.
All Reolink cameras support AAC (Advanced Audio Coding) audio format, and it cannot be changed. RTSP audio reflow supports G711 (RTSP two-way audio).