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Sounds like https://github.com/raspberrypi/userland/issues/178 Have you been rebuilding userland with modified build parameters (ie '--no-as-needed')?

The linker flags are needed when compiling picamera, not libmmal. https://github.com/raspberrypi/userland/pull/459 only changes the dependencies of the standard apps, not the libraries. libmmal does NOT depend on libmmal_vc_client. If you...

The docs at https://picamera.readthedocs.io/en/latest/api_camera.html#picamera do say > The led_pin parameter can be used to specify the GPIO pin which should be used to control the camera’s LED via the led...

If it works with a single camera connected directly to the Pi, then please raise this with the manufacturer of your multiplexer board (Arducam).

If continuously taking a capture without the board works, then it's still an issue with the board. CSI2 has per line checksums and error correction. IIRC it can cope with...

@minjianmj123 If you're getting an error relating to V4L2 and /dev/videoX, then you're not using Picamera (this library). Please post your question in a sensible place.

Note all the examples in the [docs](https://picamera.readthedocs.io/en/latest/recipes1.html) include a call to ```start_preview``` before waiting for things to warm up. AFAIK setting the properties as you've done will not start the...

Your usage of ```wait_recording``` is incorrect. It is "wait whilst recording", ie call it after ```start_recording```. It is preferable compared to time.sleep in that it handles any exceptions thrown by...

This has been covered multiple times in the forums. Any frame that is requested will be completed. On changing mode/starting the sensor the first frames after the switch is always...

The sensor can't produe 8MPix @ 30fps - see https://picamera.readthedocs.io/en/latest/fov.html#sensor-modes It'll be producing probably 1920x1080 @ 30fps and then cropping and upscaling in the ISP. The ISP will only produce...