For some surveillance projects like casino, it demands D1 display resolution and recorded resolution, that's a legal requirements for each channel to be originally recordded in D1 resolution.
D1 resolution is the highest resolution that DVR can record in. Typically, the higher the resolution you choose to record in the lower the frame rate you have to select. DVR with D1 recording solution with powerful processor. In most case, the higher of the record resolution, the more data that DVR need to process.
CIF Reslution is an image comprised of 352 X 240 Pixels, then for each channel, a 1 CIF real time (30fps) DVR needs to process 20,275,200 bits of data. (Most pixels displayed on today's systems are 8 bits of data per pixel).
D1 Resolution is an image comprised of 720 X 480 Pixels, then for each channel, a 1 D1 real time (30fps) DVR need to process (720 X 480 X 8 X30)= 82,944,000 bits of data.
960H represents the number of effective pixels in the horizontal direction of the CCD image sensor, it can provides 976 X 582 Pixels resolution, it's the highest resolution in analog cctv system.