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ucam-department-of-psychiatry / camcops

Cambridge Cognitive and Psychiatric Test Kit (CamCOPS)
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Photo preview is blank when taking a photo for the second time (Qt6.5) #310

Closed martinburchell closed 6 months ago

martinburchell commented 1 year ago

On any platform, using the photo task or anything that uses the QML camera code, take a photo and save it. Then take a second photo. The preview window just shows a black screen. Pressing the save button does actually save the second picture. You can then see it and re-take it.

https://bugreports.qt.io/browse/QTBUG-111460

From Qt6.5 with a test application built against a Qt6.5 distribution (i.e. not built by us) with FFmpeg, the problem goes away.

However, there is a problem creating a static build of Qt with FFmpeg: https://bugreports.qt.io/browse/QTBUG-115052

So for now we're stuck with using native multimedia and this bug.

martinburchell commented 7 months ago

Fixed by using FFmpeg and the C++ camera code instead of the QML version. The static build issue is now patched.