Webcam usb fswebcam

Bonjour
j’utilise une webcam logitech C270 avec fswebcam
la première acquisition d’image marche très bien, mais la suivante me mets des problèmes sur /dev/video0. Ensuite même commande et message l’gèrement différent:
stat: No such file or directory
après environ 5 secondes il est possible de faire de nouveau ne acquisition correcte, puis l’erreur revient.
ci joint les différents messages:

pi@raspberrypi:~ $ fswebcam image.jpg
— Opening /dev/video0…
Trying source module v4l2…
/dev/video0 opened.
No input was specified, using the first.
Adjusting resolution from 384x288 to 352x288.
— Capturing frame…
Captured frame in 0.00 seconds.
— Processing captured image…
Writing JPEG image to ‹ image.jpg ›.
pi@raspberrypi:~ $ fswebcam image.jpg
— Opening /dev/video0…
Trying source module v4l2…
Error opening device: /dev/video0
open: Device or resource busy
Trying source module v4l1…
Error opening device: /dev/video0
open: No such file or directory
Unable to find a source module that can read /dev/video0.
pi@raspberrypi:~ $ fswebcam image.jpg
— Opening /dev/video0…
stat: No such file or directory
pi@raspberrypi:~ $ fswebcam image.jpg
— Opening /dev/video0…
Trying source module v4l2…
/dev/video0 opened.
No input was specified, using the first.
Adjusting resolution from 384x288 to 352x288.
— Capturing frame…
Captured frame in 0.00 seconds.
— Processing captured image…
Writing JPEG image to ‹ image.jpg ›.
pi@raspberrypi:~ $

Merci de votre aide
Patrik