PiCamera cannot be initialized as a class member when the script is run from command prompt

Question

on my Raspberry Pi, I encounter a strange behaviour regarding the use of the PiCamera module.

The following code runs smoothly when either started from IDLE (F5) or from the command prompt ($python test.py)

import picamera

if __name__ == "__main__":
    camera=picamera.PiCamera()
    camera.close()

But when I put the camera object into a class the code will run only when started from IDLE (F5):

import picamera

class VF:
    def __init__(self):
        self.camera = picamera.PiCamera()

    def __del__(self):
        self.camera.close()


if __name__ == "__main__":
    myvf = VF()

When I start the above code from the command prompt, I get the following error message:

mmal: mmal_vc_component_enable: failed to enable component: ENOSPC

Traceback (most recent call last): File "test.py", line 14, in myvf = VF()

File "test.py", line 6, in init self.camera = picamera.PiCamera()

File "/usr/lib/python2.7/dist-packages/picamera/camera.py", line 379, in init camera_num, self.STEREO_MODES[stereo_mode], stereo_decimate)

File "/usr/lib/python2.7/dist-packages/picamera/camera.py", line 505, in _init_camera prefix="Camera component couldn't be enabled")

File "/usr/lib/python2.7/dist-packages/picamera/exc.py", line 133, in mmal_check raise PiCameraMMALError(status, prefix)

picamera.exc.PiCameraMMALError: Camera component couldn't be enabled: Out of resources (other than memory)

The camera module is working correct, I just stripped the code down to the least possible size. Does anybody know this problem, or a similar problem, and can probably provide a solution? The Python Version is 2.7 and the Raspberry Rasbiab-System is completely up to date. Thanks in advance.

Answer 1

I struggled with this one for hours, and kept getting the "out of resources" error. I finally figured out that in my take-the-picture function, I needed to make sure I did it like this:

    camera = PiCamera()
    (...camera settings here...)
    camera.capture(myfileName)
    camera.close()

If I didn't do the close(), I'd get that error every time. So make sure that camera.close() is getting called right after the 'snap'. It solved the problem for me.

Answer 2

Found out, that the camera-module is not properly shut down when the destructor is not explicitly called (had LED turned off, so didn't see this).

IDLE handles a running camera by somehow resetting it before the script starts, but not the python interpreter.

So everything is ok now when the destructor is called before the script ends.