I am having trouble using QML 6.4.1 on embedded linux running on IMX8 with few usb cameras which by themselves are regular UVC devices. One is working with no problems but the other 2 have a problem of camera stream not starting reliably. Once the video starts it works as long as the application is not closed. But if it fails to start i've failed to find a way to get it working other closing the app and retrying.

They all work if i start directly via gst-launch.

This is what i've managed to debug from gstreamer:

failed:
0:00:02.886514635 1554 0xfffefc4c1c10 DEBUG imxvideoconvert gstimxvideoconvert.c:308:imx_video_convert_transform_caps: transformed: video/x-raw, width=(int)[ 64, 2147483647 ], height=(int)[ 64, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]; video/x-raw, width=(int)[ 64, 2147483647 ], height=(int)[ 64, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]; video/x-raw(memory:SystemMemory, meta:GstVideoOverlayComposition), width=(int)[ 64, 2147483647 ], height=(int)[ 64, 2147483647 ], framerate=(fraction)[ 0/1, 2147483647/1 ]

 successful:

0:00:03.060808729  2234 0xffff28004de0 DEBUG        imxvideoconvert gstimxvideoconvert.c:308:imx_video_convert_transform_caps: transformed: video/x-raw, width=(int)[ 64, 2147483647 ], height=(int)[ 64, 214748364
7 ], interlace-mode=(string)progressive, multiview-mode=(string)mono, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mix
ed-mono, pixel-aspect-ratio=(fraction)[ 1/2147483647, 2147483647/1 ], chroma-site=(string)jpeg, colorimetry=(string)1:4:0:0, framerate=(fraction)30/1; video/x-raw(memory:SystemMemory, meta:GstVideoOverlayComposi
tion), width=(int)[ 64, 2147483647 ], height=(int)[ 64, 2147483647 ], interlace-mode=(string)progressive, multiview-mode=(string)mono, multiview-flags=(GstVideoMultiviewFlagsSet)0:ffffffff:/right-view-first/left
-flipped/left-flopped/right-flipped/right-flopped/half-aspect/mixed-mono, pixel-aspect-ratio=(fraction)[ 1/2147483647, 2147483647/1 ], chroma-site=(string)jpeg, colorimetry=(string)1:4:0:0, framerate=(fraction)3
0/1
To me it seems that some part of initialization fails.

Qt 6.3.1 was slightly better as only one camera failed there.

How can i debug this situation further?