The aspect ratios of ordinary cameras are 16:9,5:4 or 4:3 and an example of 16:9 is shown below, from which we can see the walls occupy a large area, while generally the walls have nothing worthy to be monitored. The corridor part that is the really valuable area takes only about 25% of the total picture, which is a waste for video compression, transmission and storage.

Corridor Mode Video Surveillance

For narrow vertical scenarios such as hallways, Some network cameras support 9:16 corridor format which can rotate the image by 90 degrees and reduce the proportion of the blank walls in the picture and make the camera focus on the valuable area—the doorway. In this way, the effective monitoring region can account for about 50% of the entire screen.