# Thread issue on startVideoCanvasPreview

**URL:** <https://devforum.zoom.us/t/thread-issue-on-startvideocanvaspreview/117458>\
**Category:** iOS\
**Created:** [September 13, 2024, 8:58pm UTC](https://devforum.zoom.us/t/thread-issue-on-startvideocanvaspreview/117458 "2024-09-13T20:58:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sp.nu](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/sp.nu/32/49481_2.png) [@sp.nu](https://devforum.zoom.us/u/sp.nu)\
**Post date:** [September 13, 2024, 8:58pm UTC](https://devforum.zoom.us/t/thread-issue-on-startvideocanvaspreview/117458/1 "2024-09-13T20:58:56Z")

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ZoomVideoSDKVideoHelper’s startVideoCanvasPreview gives  
“-[AVCaptureSession startRunning] should be called from background thread. Calling it on the main thread can lead to UI unresponsiveness”

If we call it on a background thread it gives “-[UIView bounds] must be used from main thread only”

I am assuming startVideoCanvasPreview is using AVCaptureSession’s startRunning function and that should be called on background thread.

Is Zoom planning to fix this anytime soon or does anyone has any suggestions ?

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**Author:** ![system](https://us1.discourse-cdn.com/flex016/uploads/zoomdeveloper/original/3X/6/1/614bdd549b610bbaa46ff934617683a02bdaa03c.png) [@system](https://devforum.zoom.us/u/system)\
**Post date:** [October 14, 2024, 6:59am UTC](https://devforum.zoom.us/t/thread-issue-on-startvideocanvaspreview/117458/2 "2024-10-14T06:59:11Z")

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Closed on October 14, 2024, 6:59am UTC

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