Video capture from a DVR/NVR

Please how can I video capture from multiple cameras connected to 1 DVR/NVR using either HDMI cable or IP address

Use a video capture card that supports multiple HDMI inputs and is compatible with your system. To access and handle the video feeds from each camera.

Use a C++ library like FFmpeg to connect to each camera’s IP address, allowing video capture via RTSP or HTTP protocols.

I want to live stream the feeds from the DVR/NVR using HDMI or url (‘rtsp://admin:hik12345@’) because I have 32 cameras to feed from. It is not working