THe resolution of the Sony Cyber-shot DSC-RX100 is 5472 x 3648 pixels.Sensor width = 13.20 mm, Sensor height = 8.80 mm, aspect ratio=1.5. However, when taking videos the resolution changes to 1,920 x 1,080 (16:9 aspect ratio). SO that suggests that the camera crops part of the sensors when taking videos. Is it possible to know/compute the size of the part of the sensor that is involved in taking videos?
Make a setup with a couple of rulers arranged horizontally and vertically, and the camera on a tripod, spaced so that the rulers fill the entire frame. Take a still picture, then a short video, without moving the camera. The change in field of view will be proportional to the amount of the sensor being used.
The sensor size is 8.8mm height by 13.2mm length. This is a 1.5 ratio i.e. 8.8 X 1.5 = 13.2.
When shooting video, the ratio changes to 16:9. This is a fraction 16 ÷ 9 = 1.7778 (in decimal format). If we know the dimensions of one of the two sizes of a rectangle, we can compute the other using this decimal fraction. Likely in video mode, full length of the sensor is being utilized. Thus the revised height is 13.2 ÷ 1.7778 = 7.4249. That’s the height in millimeters. The video format becomes 7.4mm height by 13.2mm length.