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Fixes Auto Exposure when v4l is the CV Backend - #49
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Nov 7, 2026
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…into dev/will/opencv_auto_exposure_fix
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When v4l is selected as the backend for OpenCV, it passes exposure mode straight through to v4l. This means the OpenCV exposure mode constants of 0.25/0.75 are not valid, and the values 1 and 3 should be used (int 0-4 instead of 0-1f). This PR checks the backend, and selects the correct constants. It also performs some ordering when leaving auto exposure to ensure the manual exposure value takes.
Also, grabbing an invalid file handle would core dump. This adds a 2 line guard with a FATAL log when the fh is invalid.
Tested locally on UC70 UVC camera.