Check for unsupported pixel format

[doug-holtsinger]

If an unsupported pixel format is handed to libcamera, then it hits an assertion error in pisp.cpp instead of returning
a proper return code. The problem was originally seen here:
opencv/opencv#21653 (comment)
I can reproduce the same issue with the latest main branch of libcamera and opencv 4.x

[naushir]

@doug-holtsinger, thank you for this fix. However, I'm a bit surprised this is needed. Do you happen to know exactly what format is originally requested to cause the failure?

[naushir]

Also, can you post the output of dmesg when the error occurs to see if the kernel driver is complaining about anything?

[doug-holtsinger]

Also, can you post the output of dmesg when the error occurs to see if the kernel driver is complaining about anything?

Here is the dmesg:
https://pastebin.com/KwRPPe28

There is a warning at line 384 but I can still use my RPi v3 camera just fine with libcamera using the YUYV format.

The failing requested format was libcamera::formats::MJPEG which is evidently not supported by my camera.

Output from 'cam -c1 -I' that lists supported Pixelformat and resolutions for my camera:
https://pastebin.com/jg3KGGSX