Psychtoolbox SYNCHRONIZATION FAILURE问题

Reference: http://psychtoolbox.org/docs/SyncTrouble

 

Reason for writing this article is to meet this problem himself, and changed the two computers will not work, annoyed, determined to figure out how it happened. Because my main windows, so this article is aimed at users of windows.

 

Error contents are generally: SYNCHRONIZATION FAILURE

 

First, we need to understand Psychtoolbox come through an accurate way to refresh the screen of a control time (although this is certainly control errors more or less, such as a general refresh rate is 60, but may be about 60.002 less or more, the relationship is not too large), then early CRT screen using the electron beam scans the screen the way

(Picture from https://blog.csdn.net/zhu_wendao/article/details/88028923 )

The need to refresh the content on the screen in the presence of memory, where there is a time to refresh after the end of the beam back to the top at this time Psychtoolbox will need to be rendered next screen into the specified memory address. In order to achieve the waiting mode screen is not flicker occurs during writing, the use of double buffering, through one after the two buffers, when necessary to exchange the two pointers can be achieved "instant filler" to avoid the transmission delay, so that the refresh rate matching is very important in the working system, such a double buffering exchange occurs in less than one microsecond, and starts synchronization VBL, accuracy of better than one microsecond. The new display, although not using this principle, but the mechanism is still reserved. If no synchronization can occur in the memory contents being refreshed during replaced, leading to tearing (the above is on a lower half of the screen is a screen next frame). Our vertical synchronization refers to, every time the screen refresh will be sent once the vertical synchronization signal (named because the old-fashioned way to refresh the screen), is equivalent to a traffic light say you can swap memory.

 

For this reason the general report is wrong, the system provides a data refresh rate and refresh interval, but the PTB zone will verify the true refresh rate and refresh time, if verified more than three times (remember three times) and can not be provided by the system almost data will be reported this wrong.

 

According to official documents :( mostly machine turn, light spray)

1. First, you need to check the graphics settings:

1. "Exchange memory synchronized to vertical retrace" option is set to "application control" or "control application, the default is open." Probably similar settings, the reason should be very clear, according to the above principle part;
2. Ensure that the "triple buffering" setting is off, or if you can choose some of the "multiple buffer" is set, it is set to "double buffering" or "wait for a video refresh" or "exchange each refresh." Now in pursuit of speed, most of the cards have multiple back buffer, it will affect the accuracy of us, so we set here so that the guarantee of accuracy;
3. If there is a "buffer exchange mode" or "Bufferswap strategies" option should be set to "Auto Select" or "page flipping" or "swap buffer." The so-called "copy buffer" or "Blitting" option causes performance degradation and timing is not accurate;
4. On a dual / multi-monitor set, MS-Windows allows you to assign "master monitor" role or "main display" as a monitor. Importantly, the display device for stimulating the presentation of the "main show", or it may be wrong. Of course, this is also generally write (i.e. screenNumber = max (screens);) of the code Psychtoolbox;
5. A plurality of displays, please select "Extended" manner;
6. All operating systems or in dual-display mode in the display, to display a plurality of stimulation on a display, for example, for a binocular on dual-display, the display is configured as two identical color depth, resolution and the refresh rate is very important.
7. If you have some options, you can select "genlock mode" or "Only sync lock mode", select or enable this option. If you dual monitors stimulus, failed to configure such a dual display setting will cause a lot of timing issues or on one display tearing artifacts. It may also cause timing failure.

1. Driver / hardware issues

The problem is the next easiest way to try the latest drivers, the problem may be caused by driving over the old version.

The usual suspects are: virus scanners, hard disk or network access applications, iTunes and other applications, system software updates ...... bad drivers or hardware system interference in the general system timing: It is difficult to diagnose.

At least on MS-Windows, you can download the free tool "dpclat.exe" from the Internet (using Google to find). If you run it, it will tell you whether there are potential problems with the system time, and provides tips on how to solve them.

Of course, the following command can be used directly skip this detection area,

Screen ( ' the Preference ', 'SkipSyncTests',. 1); This command causes the last measured interval as the interval of time (it may be the maximum 3S )

 

 

The last problem is the interference of the software. Uninstall antivirus software like on the computer.

 

If all else fails, a high probability your windows system is, I just do not toss directly for Linux on System