# What is the Frame rate of a video ? (ie frame per Second (FPS) or frame frequency)

Frame rate (expressed in frames per second or fps) is the frequency/speed (rate) at which consecutive images called frames appear on a display.

The term applies equally to film and video cameras, computer graphics, and motion capture systems.

Frame rate may also be called the frame frequency, and be expressed in hertz.

Note that: $$1 \text{Hertz} = 1 \text{Frames Per Second}$$

The number of frames that is displayed each second has a direct impact on how smooth (life-like), a video (or user interface) seems to be.

## Rendering, unresponsive and FPS

• If a video application can not put up 1 new picture, or frame in the display buffer because of performance before each screen refreshes (ie every 10ms)
• the frame rate drops (frame are not shown),
• the content judders on screen (often referred to as jank)

For instance:

• with a normal monitor device that display 60 frames per second,
• the application got about 16.67ms to generate a frame (static image)
• If the application is unable to create a frame within this 16.67ms, a frame will drop (miss an interval)
• and the UI will appear unresponsive.

## Human

humans perceive individual images as motion with frame rates:

• around 10 to 15 Hz up
• to 60 Hz.