Guide to graphic display settings for game players (9) (The gamer's graphics & Display Settings Guide)

Guide to graphic display settings for game players (9)

Translated by koroush Ghazi

Ninth Level graphics settings-Vertical synchronization

Vertical synchronization

Vertical synchronization (vertical sync, short for vsync) is mainly due to physical limitations of the picture tube, which has been pointed out in the chapter on refresh rate. The CRT display must display the image by constantly illuminating the phosphor on the screen, which is based on the moving speed of the display electron gun. Each time the CRT Displays re-draw the entire screen, the internal electron gun will move from the bottom of the screen to the point pointing to the upper left corner of the screen, prepare 'redraw 'All scanning lines from the upper left corner to the lower right corner of the screen, after finishing the painting, prepare the next refresh from the beginning. In order to refresh the screen, the time for the electron gun to move from the bottom of the screen to the top is called the vertical blanking interval (VBI ).

Enabling vsync on the video card will tell you that the video card will be synchronized with your display. This means that the video card is only allowed to swap its frame cache and send a new frame to the video card when the display says it is ready to re-draw the entire Screen-for example, during VBI. However, you do not have to synchronize your video card with the monitor. When vsync is disabled, they can still run normally, but when the vertical scan is disabled, you can experience a phenomenon called tearing, which is precisely because there is no mutual restriction between your graphics card and the display.

Although the concept of vsync originated from the CRT screen, it is applicable to LCD display, and we will explain why it is said in the future.

 

Tearing)

If you disable vsync, your video card and display will not be synchronized, which is unfortunate. Whenever your FPS exceeds the screen refresh rate (for example, FPS is 120 on a 60Hz screen), or when your video card is working faster than the display, the video card will generate more frames in the frame cache area than the number of frames actually displayed by the display, so the final result is, when a display obtains a new image from the main buffer zone of the video card during VBI, this frame may actually be produced by the overlap of two or more different frames. On the screen, it may appear that whenever any motion picture appears, it will be slightly non-aligned or 'partially torn '-so it is called a tear. The following example is used to simulate this situation. Take a closer look at the restroom and sink-some of which are not aligned due to the tear:

 

The visual impact of tearing mainly depends on how serious the inconsistency between your video card and the display is, but generally, in a higher FPS or faster action game, such as the rapid reversal, this impact will be more obvious. This is because in these cases, the difference between the new and old overlapping frames is more obvious.

Tearing will not cause any damage to your video card or display. It only shows that when the video card and the monitor are not synchronized, the display physically needs to keep up with the speed limit of the video card. For example, if you run 120fps on a 60Hz display, you can only refresh up to 60 complete frames in any second. Therefore, other 60 frames are almost wasted, the solution is that many frames overlap and thus a tear occurs. Therefore, even if you do not want to enable vsync, you should set it in the game graphics settings to reduce your FPS and bring it closer to your refreshing rate. This will help you get more frames and reduce the tear. This looks cool, because you will have a high frame rate, but when vsync is disabled, you can still see that there is a waste of frames and it will cause image failure.

Whether it is a CRT or LCD display, there will be a tear, because both work for the same purpose of compatibility-see the response time section to explain why LCD displays behave like CRT monitors.

FPS and vertical synchronization

When vertical synchronization is disabled, there is no relationship between your FPS and the update rate. This allows your video card to work as quickly as possible and send frames to the display as soon as possible. Of course, whether the display can correctly display all these frames is another matter. In fact, we have already discussed this issue. Obviously, if vsync is disabled, it may lead to graphical glitches, but these faults may be minor. Why can't I always turn vsync on because of some tearing? Once again, things are often not that simple.

When vertical synchronization is enabled, what happens is that your video card is told to wait until your monitor sends a signal that a new frame of image is displayed, provide a new image. The video card cannot lead any more. After it is ready, it cannot overlay a new frame on the old frame-it must provide a single frame only after the display says that it has been accurately refreshed during VBI. First, the most obvious effect is that your FPS will be limited to the current refresh speed limit. Therefore, if you set the update rate to 60Hz, your frame rate can only reach 60 frames per second. This is not a real problem because each display can reach at least 60Hz at any resolution, which has been discussed in the "Number of frames per second" chapter, if your system can generate continuous 60 FPS in a game, you will get smooth and natural movements in any game.

However, one of the most fundamental problems that will occur when vsynci is enabled isGreatly reduce your overall Frame Rate, Which usually reduces your FPS to a 50% update rate. This is a difficult concept to explain, but it still takes time to explain it. We know that when vsync is enabled, your video card will almost become a slave to your monitor. If your FPS is slightly lower than the refresh rate at any time, it takes longer to draw a frame for your video card than to refresh your display. Therefore, when you refresh your video card for the second time, you miss the time to create a new frame. This means that no matter whether its primary buffer and backup buffer are filled up, new image information will be available everywhere, so it must be idle, wait for the next update to upload the recently generated frame to the buffer and start clearing the backup buffer. This results in nearly half of the frame rate loss when your FPS is lower than the refresh rate.

As long as your video card provides faster frames than your monitor automatically refreshes, enabling vsync will not reduce your average frame rate. All of this happens, only because the maximum limit of your FPS is limited to the screen update rate. However, since the update rate of modern displays is more than 60Hz, it is difficult to achieve stable 60fps in most games with the resolution and settings you need, therefore, enabling vsync usually reduces your FPS. Fortunately, because there is no buffer to fill too many frames, there is a solution that uses three buffers. However, this is not a simple solution. For more details, see the "triple buffer" section.

So which one is better? Enable or disable vertical synchronization?

The existence of vsync is indeed a problem for many people: When the vertical synchronization is disabled, when your video card and the display are not synchronized, it will lead to a tear, which is very annoying for some people, especially in fast-moving games. However, when vsync is enabled, your FPS is usually reduced to 50%. The triple buffer system can solve this problem, but it also brings potential problems. Therefore, how do you choose?

Obviously, I cannot give you an answer that fits everyone's size, but I can provide some suggestions. First, we strongly recommend that you set vsync as an application.Program'Preference '(or a control panel similar to a graphics card ). This is because you should set vsync based on different games, that is, it is best to use the settings in the game. Different types of games will lead to different choices. For example, newer games often have complex graphics, which is different from old games that can easily run on your machine. Remember, in the game, if your FPS is always higher than the refresh rate you set, it is good to enable vsync without lowering the FPS.

In general, I suggest you disable vsync in any game, because this is the most direct way to achieve the fastest performance. This is the simplest solution if your display has a low update rate or a low frame rate in the game. You may notice some tears, but this is very small when your FPS is less than the refresh rate. Remember, even if your FPS exactly matches your refresh rate, or even lower, once vsync is disabled, that is, the video card and the monitor are not strictly synchronized, then tear (although not obvious) it may happen at any time.

In the game, if you find tearing annoying, you should enable vsync. If you find that your FPS is halved, you should try to enable the triple buffer, because this can help fix the FPS decrease caused by enabling vsync, however, it introduces new problems, especially when the video card memory is small, it is easy to cause display failure on the video card, and control system latency. For details, refer to the "triple buffer" section.

There is no option available for everyone about vertical synchronization, which is why the option to enable or disable vsync exists in the graphics card control panel and in the game. As long as you understand it, you can choose a reasonable setting.

 

Previous

next article