What does frame rate mean?

The frame rate is the frequency (rate) at which bitmap images in units of frames appear continuously on the display; the frame rate can also be called the frame frequency and is expressed in Hertz (Hz). The frame rate per second indicates the number of times the graphics processor can update per second when processing the field. A high frame rate can result in smoother and more realistic animations; the more frames per second (frame rate), the more action is displayed. It will become smoother.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

Frame rate (Frame rate) is the frequency (rate) at which a bitmap image in units of frames appears continuously on the display. The term applies equally to film and video cameras, computer graphics and motion capture systems. Frame rate may also be called frame frequency and is expressed in Hertz (Hz).

Frames per second (fps) or frame rate represents the number of times the graphics processor can update per second when processing the field. A high frame rate results in smoother, more realistic animations. Generally speaking, 30fps is acceptable, but increasing the performance to 60fps can significantly improve the sense of interactivity and realism. However, generally speaking, it is not easy to notice a significant improvement in smoothness beyond 75fps.

Each frame is a still image, and displaying frames in rapid succession creates the illusion of motion. A high frame rate results in smoother, more realistic animations. The more frames per second (fps), the smoother the displayed action will be. In the past, the reason why Android was criticized for being unsmooth was because of its low frame rate during operation.

Frame Rate and Human Vision

The temporal sensitivity and resolution of human vision vary depending on the type and characteristics of the visual stimulus and differ between individuals. The human visual system processes 10 to 12 images per second and perceives them individually, with higher rates perceived as motion. Most study participants considered modulated light, such as a computer monitor, to be stable at rates above 50 Hz to 90 Hz. This steady feeling of modulated light is called the flicker fusion threshold. However, when the modulated light is non-uniform and contains images, the flicker fusion threshold can be much higher, hundreds of Hz. Regarding image recognition, people have been found to recognize specific images in an uninterrupted series of different images, each lasting as little as 13 milliseconds. Persistence of vision sometimes results in very short, single-millisecond visual stimuli with perceived durations ranging from 100 ms to 400 ms. Very short multiple stimuli are sometimes perceived as a single stimulus, such as a 10 ms green flash followed by a 10 ms red flash, perceived as a single yellow flash.

Refresh rate

Refresh frequency: the speed at which the screen refreshes.

The lower the refresh frequency, the more the image will flicker, pause and jitter, and the faster your eyes will tire.

Flicker can be basically eliminated when a refresh frequency of 70Hz or above is used. It is best for the monitor to work stably at the highest allowed frequency, which is generally 85Hz.

Inside the display, there are some oscillation circuits.

The refresh frequency that people usually refer to refers to the frequency of the oscillation circuit.

The calculation formula of refresh frequency is: horizontal synchronization scanning line X frame rate = refresh frequency.

The refresh frequency of ordinary monitors is between 15.75kHz and 95kHz.

15.75kHz is the minimum refresh frequency required by the human body for the display, which is calculated from 525 (line) X30 (fps) = 15.75kHz.

From this, we can reversely deduce the time it takes for the monitor to scan a horizontal line: As we all know, time and frequency are reciprocal, that is, 1/frequency = time.

Here, 1/15.75kHz= 63.5us (microseconds), which means that in the mode of 525 lines per frame and 30 frames per second, the time it takes for the monitor to scan a horizontal line is 63.5 microseconds. .

Influencing factors

Since the faster the refresh rate, the better, why should we emphasize that there is no need to pursue a refresh rate that is too high?

The reason is that when the display 'resolution' remains unchanged, the higher the FPS, the higher the processing power requirements for the graphics card.

The images displayed on the computer are all output by the graphics card, so the filling of each pixel on the screen must be calculated and output by the graphics card.

When the resolution of the picture is 1024×768, the refresh rate of the picture must reach 24 frames/second, then the number of pixels that the graphics card needs to process in one second will reach “1024×768×24= 18874368".

If the refresh rate of the screen is required to reach 50 frames/second, the amount of data will suddenly increase to "1024×768×50=39321600".

The relationship between FPS, resolution and graphics card processing power is as follows:

Processing power = resolution × refresh rate. This is why when playing games, the larger the resolution setting, the less smooth the picture will be.

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