Raspberry Pi：使用IF环路检测摄像头，gphoto2

Question

I'm trying to find a way to detect if a camera is found for gphoto2, or not.

I've posted in the gphoto2 forum, but figured I'd try here too. One can issue the command, gphoto2 --auto-detect, and it will list cameras that are detected.

I'm running a large python script that at one point, calls gphoto2 to take a picture and download the image. I'm wanting to find a statement that I can put in an IF Loop, to where the take picture and download image command is only issued after entering in the loop if the camera is detected.

Answer 1

quick google reveals python bindings for gphoto2 http://magiclantern.wikia.com/wiki/Remote_control_with_PTP_and_Python .

Other variant is to call a console command ie

from subprocess import call
call(["gphoto2", "--auto-detect"])

It is up to you how long you will wait for camera to be detectend before you give up.

If you are going with loop, remember to put some sleep command in.

timeout = time.time() + 60
detected = False
while time.time() < timeout:
    if is_device_available():
        detected = True
        break
    # maybe show some feedback why he has to wait
    time.sleep(1)
if not detected:
    raise Exception('Camera device not detected')