# video vertical sync

**URL:** <https://forums.imgtec.com/t/video-vertical-sync/899>\
**Category:** PowerVR Insider\
**Created:** [November 8, 2010, 11:02am UTC](https://forums.imgtec.com/t/video-vertical-sync/899 "2010-11-08T11:02:02Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![zakky](https://avatars.discourse-cdn.com/v4/letter/z/45deac/32.png) [@zakky](https://forums.imgtec.com/u/zakky)\
**Post date:** [November 8, 2010, 11:02am UTC](https://forums.imgtec.com/t/video-vertical-sync/899/1 "2010-11-08T11:02:02Z")

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hi,

&nbsp;
  

I'm work on Opengl ES 1.1 PC emuration downloaded from IMG site(OGLES\_WINDOWS\_PCEMULATION\_2.07.27.0484.msi).
  

I add eglSwapInterval(eglDisplay, 2); at initialization code (just before &nbsp;// Draws a triangle for 800 frames comment)of OGLESHelloTriangle\_Windows.cpp under TrainingCource2\_HelloTriangle directory.
  

I expected a triangle drawing of 800 frames to become slow but 
  

there was no change at the drawing speed. 
  

&nbsp;
  

Is the usage of API wrong?
  

&nbsp;
  

If anyone knows the way to slow the frame rate using eglSwapInterval,  
please let me know.
  

&nbsp;
  

Best regards,
  

Zakky  

  

&nbsp;
  

&nbsp;

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<div class="post-metadata">

**Author:** ![JoeDavis](https://sea1.discourse-cdn.com/flex015/user_avatar/forums.imgtec.com/joedavis/32/71_2.png) [@JoeDavis](https://forums.imgtec.com/u/JoeDavis)\
**Post date:** [November 24, 2010, 10:26am UTC](https://forums.imgtec.com/t/video-vertical-sync/899/2 "2010-11-24T10:26:50Z")

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Hi Zakky,  
  
  
  
  
  
The usage of the API seems ok. The values that can be accepted by this function depend on the values of EGL\_MIN\_SWAP\_INTERVAL and EGL\_MAX\_SWAP\_INTERVAL (as explained [here](http://www.khronos.org/opengles/sdk/1.1/docs/man/eglSwapInterval.xml)). Also, I’m not 100% sure, but I think the maximum supported value may be capped depending on the driver implementation.  
  
  
  
  
  
 Just out of curiosity, what are you trying to achieve by limiting the frame rate? You may find limiting the frame rate within your application a more suitable approach in many cases instead of relying on the driver to do this for you as this will give you much more control over the final frame rate of your applicationJoe2010-11-24 11:27:26