How Are Video Frame Rate and Screen Refresh Rate Different? (original) (raw)

When shopping for a TV or computer monitor, it's easy to get overwhelmed by terms like progressive scanning, 4K Ultra HD, frame rates, and screen refresh rates. While those last two sound like the same thing, there's a subtle difference between them, which is why we've compiled a guide to the differences between refresh rate vs. FPS.

Frame Rate

Refers to the number of frames displayed every second.
Measured in FPS (frames per second).

Refresh Rate

Refers to how many times the display refreshes per second.
Measured in Hz (hertz).

Frame Rate Pros and Cons

Advantages

Higher frame rates reduce choppiness, especially for video games.
Modern Blu-ray players output the same FPS as standard film.

Disadvantages

Most movies and TV shows are shot at 30 FPS or lower, so a 60 FPS display won't make a difference.
Recording in higher frame rates results in bigger file sizes.

Just like traditional film, digital videos display images as individual frames. Frame rate refers to the number of frames-per-second (FPS) a television can display. These frames are displayed using the interlaced scan method or the progressive scan method. Frame rates are often listed alongside the video resolution. For example, 1080p/60 TV has a frame rate of 60 FPS.

TV manufacturers have introduced a number of features to improve the frame rate. For example, some TVs use a technique called frame interpolation, in which the video processor combines elements of successive frames to blend them together for smoother motion rendering. The downside of this effect is that it can make movies shot on film look like they were shot on digital video.

Since the film is shot at 24 frames-per-second, the original 24 frames must be converted to display on a typical television screen. However, with the introduction of Blu-ray Disc and HD-DVD players that can output a 24 frame per second video signal, new refresh rates have been implemented to accommodate these signals in the correct mathematical ratio.

Refresh Rate Pros and Cons

Advantages

High refresh rates improve motion rendering.
High refresh rates make a noticeable difference when playing games at high FPS.

Disadvantages

Faster refresh rates aren't always noticeable.
Low refresh rates compared to FPS can cause screen tearing while gaming.

The refresh rate represents how many times the display is completely reconstructed every second. The more times the screen is refreshed, the smoother the image is in terms of motion rendering and flicker reduction.

Refresh rates are measured in hertz (Hz). For example, a television with a 60 Hz refresh rate represents a complete reconstruction of the screen image 60 times every second. If the video is rendered at 30 FPS, then each video frame is repeated twice.

One technique that some TV manufacturers use to reduce motion blur is referred to as backlight scanning, in which a backlight flashes on and off rapidly between each screen refresh. If a TV has a 120 Hz screen refresh rate, backlight scanning delivers the effect of having a 240 Hz screen refresh rate. This feature can be enabled or disabled separately from the screen refresh rate setting.

Enhanced refresh rates, backlight scanning, and frame interpolation apply primarily to LCD and LED/LCD displays. Plasma TVs handle motion processing differently, utilizing a technology referred to as a Sub-Field Drive.

Frame Rate vs. Refresh Rate: Which Matters More?

If the screen's refresh rate cannot keep up with the frame rate, it can result in screen tearing, or multiple frames displaying at once. This rarely happens when watching television. It typically occurs when playing GPU-intensive video games. If you're a PC gamer, choose a monitor with a 240 Hz refresh rate. When watching TV, the refresh rate and frame rate matter less than the video resolution.

To market TVs that use faster frame rates and refresh rates, manufacturers have created their own buzzwords to draw the consumer in.

Examples of motion processing (aka Motion Smoothing) buzzwords used by manufacturers include TruMotion (LG), Intelligent Frame Creation (Panasonic), Auto Motion Plus or Clear Motion Rate (Samsung), AquaMotion (Sharp), Motion Flow (Sony), ClearScan (Toshiba), and SmoothMotion (Vizio).

Don't get too bogged down with the numbers and terminology. Let your eyes be your guide as you compare TV displays. Make sure the TV is powerful enough to support your media players and video game consoles. For example, to play video games in 4K at 60 FPS, choose a TV capable of displaying high resolutions and fast frame rates.

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