title: capture picture from linux command line (uvccapture captures black picture)
body: <p>As in the topic, when I run:</p>
  
  <pre><code>sudo uvccapture -S40 -C30 -G80 -B20 -x1280 -y720 -v
  </code></pre>
  
  <p>I get a big black picture (the same result with -m flag)</p>
  
  <p>BUT, when I run:</p>
  
  <pre><code>sudo uvccapture -S40 -C30 -G80 -B20 -x1280 -y720 -v -t5
  </code></pre>
  
  <p>Which means It will take a picture every 5 seconds.<br>
  it works good (picture is ok).<br>
  But I can't use that command, cause it won't stop taking pictures.</p>
  
  <p>Do you know what can be wrong?</p>
  
  <p>result:</p>
  
  <pre><code>Using videodevice: /dev/video0  
  Saving images to: snap.jpg  
  Image size: 1280x720  
  Taking snapshot every 0 seconds  
  Taking images using mmap  
  Resetting camera settings  
  ioctl querycontrol error 22  
  Setting camera brightness to 20  
  Setting camera contrast to 30  
  Setting camera saturation to 40  
  Setting camera gain to 80  
  ioctl querycontrol error 22  
  Saving image to: snap.jpg  
  </code></pre>
  
  <p>lsusb:</p>
  
  <pre><code>Bus 001 Device 004: ID 041e:4088 Creative Technology, Ltd
  </code></pre>
  
  <p>dmesg:</p>
  
  <pre><code>[3.192732] usb 1-1.3: new high-speed USB device number 4 using dwc_otg
  [3.321292] usb 1-1.3: New USB device found, idVendor=041e, idProduct=4088
  [3.334037] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  [3.343098] usb 1-1.3: Product: VF0700 Live! Cam Chat HD
  [3.350192] usb 1-1.3: Manufacturer: Creative Technology Ltd.
  [3.357531] usb 1-1.3: SerialNumber: 2G130236
  [3.949616] udevd[154]: starting version 175
  [5.197753] Registered led device: led0
  [5.294970] Linux media interface: v0.10
  [5.499646] Linux video capture interface: v2.00
  [6.009958] uvcvideo: Found UVC 1.00 device VF0700 Live! Cam Chat HD (041e:4088)
  [6.210327] input: VF0700 Live! Cam Chat HD as /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/input/input0
  [6.369436] usbcore: registered new interface driver uvcvideo
  [6.502467] USB Video Class driver (1.1.1)
  </code></pre>