video.start() .. invokes an IOError

Bug #552663 reported by Ben
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
python-v4l2capture
Undecided
Fredrik Portström

Bug Description

sorry if this is wrong, I am very new to Python.

I have install the module but when running the code supplied, i get the following:

./capture_picture.py

  libv4l2: error turning on stream: Invalid argument
  Traceback (most recent call last):
    File "./capture_picture.py", line 31, in <module>
       video.start()
   IOError: [Errno 22] Invalid argument

I am pretty sure the camera is working using v4l2 as using ffmap as follows works:

  vlc-wrapper -vvv v4l2:///dev/video0 :v4l2-fps=2 :v4l2-brightness=-1 :v4l2-contrast=-1 :v4l2-saturation=-1 :v4l2-black-level=-1 :v4l2-auto-white-balance=-1 :v4l2-exposure=-1 :v4l2-autogain=-1 :v4l2-hue=-1 :v4l2-width=640 :v4l2-height=480 --sout=/root/bens_tests/images/video.avi

I am using a USB "Z-Star Microelectronics Corp. ZC0303 Webcam" (Driver: zc3xx) and I am on Ubuntu 9.10
  (uname -a output: "Linux nb-03 2.6.31-20-generic #57-Ubuntu SMP Mon Feb 8 09:05:19 UTC 2010 i686 GNU/Linux")

Please let me know if you any more information... .or if I am missing something or doing something wrong.

Many thanks,
-Ben

Revision history for this message
Fredrik Portström (portstrom) wrote :

I've heard about this problem before. It seems to be that some devices require Video_device.queue_all_buffers to be called before Video_device.start. I've made a new release with the example script forked into two separate scripts, capture_picture.py which should work for you and capture_picture_delayed.py which is equal to the old script except new comments. Tell if this solves your problem.

Changed in python-v4l2-capture:
assignee: nobody → Fredrik Portström (rheo)
status: New → Fix Released
Revision history for this message
Ben (bugthing) wrote :

Excellent!... works very nicely now.
Thank you very much for sorting this out so quickly.
I will be playing with this for a while now adjusting brightness etc... but now I can get an image its a good start :)

I work for a small IT company in the UK... if we can help you in return please let me know (hosting, etc.)

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