The relationship and difference between video bit rate, frame rate and resolution

Which of the video bit rate, frame rate and resolution affects the clarity of the video?

--------------Video bit rate--------------

First, the introduction of the bit rate The
       bit rate is the number of bits of data transmitted per unit time during data transmission , Generally, the unit we use is kbps, that is, thousands of bits per second. The popular understanding is the sampling rate or bit rate (not the same as the sampling rate, the unit of sampling rate is Hz, which means the number of samples per second). The larger the sampling rate per unit time, the higher the accuracy, and the processed files The closer it is to the original file, but the file size is proportional to the sampling rate, so almost all encoding formats focus on how to use the lowest bit rate to achieve the least distortion. Around this core, cbr (fixed bit rate) and vbr (variable bit rate), "bit rate" is the degree of distortion, the higher the bit rate, the clearer the picture, otherwise the picture will be rough and more mosaic. For example, for an audio, the higher the bit rate, the smaller the compressed ratio, the smaller the loss of sound quality, and the closer to the sound quality of the audio source.
2. Calculation formula The
basic algorithm is: [code rate] (kbps) = [file size] x8 x 1024/[time] (seconds)
3. Several principles of code rate:
1. The code rate is proportional to the quality, but the file The volume is also proportional to the bit rate. This is to keep in mind.
2. If the bit rate exceeds a certain value, it has little effect on the quality of the image.
3. The capacity of DVD is limited, whether it is standard 4.3G, over-engraved, or D9, there are limits. The information in the video rate computer is represented by binary 0s and 1s, and each 0 or 1 is called a bit, which is represented by lowercase b, that is, bit (bit); uppercase B is byte, that is, byte, a Byte = eight bits, that is, 1B=8b; the uppercase K in the front means 1024, that is, 1024 bits (Kb) or 1024 bytes (KB). Indicates the size of the file, generally using bytes (KB) to indicate the size of the file.
Kbps: The first thing to understand is that ps refers to /s, which is every second. Kbps refers to the network speed, that is, how many thousand bits of information are transmitted per second (K means thousand bits, Kb means how many thousand bits). Expressed in kb (thousands). 1KB/S=8Kbps. The Internet speed of ADSL is 512Kbps. If it is converted into bytes, it is 512/8=64KB/S (that is, 64 kilobytes per second).
4. Generally speaking, if the broadband is 1M, you can only watch the video of no more than 1024kbps on the Internet, and the video of more than 1024kbps can only be watched smoothly after the video is buffered.
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-------------- Video frame rate --------------
First, the introduction of the

        video frame rate (Frame rate) is A metric used to measure the number of displayed frames. The so-called unit of measurement is the number of frames per second (Frames per Second, abbreviated: FPS) or "Hertz" (Hz). This term is mostly used in film and video production and video games.
       Due to the special physiological structure of the human eye, if the frame rate of the viewed picture is higher than 16, it will be considered coherent, and this phenomenon is called visual stop. That's why film footage is shot frame by frame and played back quickly.
       For games, generally speaking, first-person shooters pay more attention to the level of FPS. If FPS<30, the game will appear incoherent. So there is an interesting saying: "FPS (referring to FPS games) focuses on FPS (referring to frame rate).
       Frames per second (fps) or frame rate represents the number of updates per second that the graphics processor can process a field. Higher frame rates result in smoother, more realistic animations. Generally speaking, 30fps is acceptable, but increasing the performance to 60fps can significantly improve the sense of interaction and realism, but generally speaking, it is not easy to notice a significant improvement in fluency beyond 75fps. If the frame rate exceeds the screen refresh rate it just wastes the power of the graphics processing, because the monitor cannot update so fast, so the frame rate exceeding the refresh rate is wasted.        2. Frame rates in the

media are:

Movie: 23.976fps
TV (PAL): 25fps
TV (NTSC): 29.97fps
CRT Display: 60Hz-85Hz
LCD Display: 60Hz-75Hz 3D
Display: 120Hz The faster the better, why stress that there is no need to pursue too high a refresh rate? The reason is that when the display 'resolution' remains unchanged, the higher the FPS, the higher the requirements for the processing power of the graphics card.        The pictures displayed in 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 screen is 1024×768, the refresh rate of the screen must reach 24 frames per second, then the amount of pixels that the graphics card needs to process in one second reaches “1024×768×24=18874368”.        If the refresh rate of the screen is required to reach 50 frames per second, the amount of data is suddenly increased to “1024×768×50=39321600”.        The relationship between FPS and resolution and graphics card processing power is as follows:









       Processing power = resolution × refresh rate. This is why when playing games, the higher the resolution is set, the less smooth the picture will be.
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--------------Video resolution--------------

First, the introduction
       video resolution is all kinds of monitor screen There are only three common screen ratios: 4:3, 16:9 and 16:10, plus a special 5:4.
The relationship and difference between video bit rate, frame rate and resolution



     · What is D1?


D1 is the standard of digital TV system display format, which is divided into the following 5 specifications:

D1: 480i format (525i): 720×480 (horizontal 480 lines, interlaced scan), the same definition as NTSC analog TV, the line frequency is 15.25 kHz, equivalent to what we call 4CIF (720×576)

D2: 480P format (525p): 720×480 (horizontal 480 lines, progressive scan), much clearer than D1 interlaced scan, and progressive scan DVD specification The same, the line frequency is 31.5kHz

D3: 1080i format (1125i): 1920×1080 (horizontal 1080 lines, interlaced scan), the HD mode adopts the most resolution, the resolution is 1920×1080i/60Hz, and the line frequency is 33.75 kHz

D4: 720p format (750p): 1280×720 (horizontal 720 lines, progressive scan), although the resolution is lower than D3, but because of progressive scan, more people on the market feel that it is relative to 1080I (actually 540 lines successively) The visual effect is clearer. However, in my personal opinion, when the maximum resolution reaches 1920×1080, D3 feels clearer than D4, especially in terms of text expressiveness. The resolution is 1280×720p/60Hz, and the line frequency is 45kHz.

D5: 1080p format (1125p): 1920×1080 (horizontal 1080 lines, progressive scan), currently the highest standard of high-definition video for civilian use, with a resolution of 1920×1080P/60Hz and a line frequency of 67.5KHZ.

Among them, the D1 and D2 standards are the highest standards of our general analog TV, and cannot be called high-definition. The 1080i standard of D3 is the basic standard of high-definition TV, which is compatible with the 720p format, while the 1080P of D5 is only a professional standard.





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Frame rate: It affects the smoothness of the picture, which is proportional to the smoothness of the picture: the larger the frame rate, the smoother the picture; the smaller the frame rate, the more pulsating the picture is. If the bit rate is variable, the frame rate will also affect the volume. The higher the frame rate, the more pictures passed per second, the higher the required bit rate and the larger the volume.
The frame rate is the number of frames of pictures transmitted in 1 second. It can also be understood that the graphics processor can refresh several times per second.

Resolution: affects the size of the image and is proportional to the size of the image: the higher the resolution, the more Larger; the lower the resolution, the smaller the image.

Sharpness
Under the condition of a certain bit rate, the resolution is inversely proportional to the sharpness: the higher the resolution, the less clear the image is, and the lower the resolution, the clearer the image.
In the case of a certain resolution, the bit rate is proportional to the definition, the higher the bit rate, the clearer the image; the lower the bit rate, the less clear the image.