Judder refers to a visual artifact or distortion that can occur when there is a discrepancy between the frame rate of a video source and the refresh rate of a television display. It manifests as a jerky or stuttering motion in the displayed content.
The problem of judder arises from the difference in the frame rates of the video source and the refresh rate of the TV display. Most movies and TV shows are filmed at a standard frame rate of 24 frames per second (fps), while typical television displays have a refresh rate of 60 Hz or 120 Hz.
To display content filmed at 24 fps on a TV with a higher refresh rate, a process called 3:2 pulldown or 2:3 pulldown is employed. This process involves repeating or duplicating certain frames to match the refresh rate of the TV. However, this conversion can result in judder, as the uneven distribution of duplicated frames can lead to inconsistent motion.
Judder is particularly noticeable when panning shots or camera movements occur in the video content. The stuttering effect can be distracting and take away from the smoothness and fluidity of the viewing experience, especially in film and cinematic content.
TV manufacturers have implemented various technologies to mitigate judder and provide smoother motion in their displays. Some of these technologies include motion interpolation, frame interpolation, and black frame insertion. These techniques aim to fill in the gaps and create additional frames to match the refresh rate of the TV, resulting in smoother motion.
However, it’s important to note that while these technologies can reduce judder, they may introduce other artifacts or effects, such as motion blur or the soap opera effect. The preference for motion handling can vary among viewers, and it’s often a matter of personal preference.
To address judder, TV manufacturers and content creators are increasingly focusing on higher frame rate formats, such as 60 fps or 120 fps, which align better with the native refresh rates of modern TVs. This can provide a smoother and more natural viewing experience without the need for additional frame rate conversion techniques.