v4l

rubadub · 10-23-2006, 05:12 PM

Hi,
Right, i'm installing a web-cam, it seems to have gone ok, yet none of my python libaries are finding it.

I'm running Fedora 4, with kernel 2.6.17-1.2142_FC4, my output from lsusb is, Bus 002 Device 002: ID 046d:0921 Logitech, Inc. Labtec WebCam.

Okay, down to the nitty gritty.
I made and installed the 'spca50x' (gspcav1-20060925.tar.gz) driver.
Next, I:
# mknod /dev/video0 c 81 0
Then:
# /sbin/modprobe -v gspca
I'd set group permissions etc, then tested with a script for mplayer and mencoder. Everything seems to work ok.

Now down to real business:

First I tried "libfg"
For 'libfg', I run the basic script as follows, but it gives me the following error, any ideas?

Code:

# #!/usr/bin/env python
#
# import fg
# g = fg.Grabber ()
# g.set_source(0)
# g.demo('test01.pgm')

Quote:

$ python test2.py
fg_open(): open video device failed: No such file or directory
fg_set_source(0)
Segmentation fault

For 'Pyv4l' i'm using the included script 'tv.py' (pls find yourself, it's included in the install).
But yet again I get an error and i'm not sure why, any ideas?

Quote:

$ python tv.py
Device Name: Labtec Webcam
Type: 1
Channels: 1
Audios: 0
Maximum Width: 352
Maximum Height: 288
Minimum Width: 160
Minimum Height: 120
(0, 'TV8532', 0)
Traceback (most recent call last):
File "tv.py", line 24, in ?
vid.setFrequency(216250)
v4l.V4lError: Error setting frequency.

Also i've found 'pyvideograb'. I installed this, then ran the test.py script. Here's my error output:

Quote:

# python test.py
Opening device...
Traceback (most recent call last):
File "test.py", line 21, in ?
pixelformat=v4l2_consts.V4L2_PIX_FMT_GREY
directvideo.DirectVideoError: /dev/video0 is no V4L2 device

From this it seems that my device isn't a v4l device. So, i've been back to the v4l site and verified the driver i'm using is on their list, the SPCA50X USB Camera Linux Driver, 'gspcav1-20060925.tar.gz'.

This error could be the way to solving the problems with the other programs. Does anybody have any suggestions to the setup of my device or for checking it?

rubadub · 10-23-2006, 05:23 PM

Sorry, a bit drunkard like!

To summerise, have I set the device up as v4l or v4l2 device, if not how. Or is there any other libaries / modules for python that I can use to grab stills?

rubadub · 10-24-2006, 12:19 PM

I know it's pushy, yet I really could do with some assistance cos i'm at a loss, therefore i'm jumping to the top!

Phorem · 10-24-2006, 02:01 PM

Why did you do....

mknod /dev/video0 c 81 0

??

Where did you read you are supposed to do that? Remove that device.

Really, i think, all you are/were supposed to do is make the gspcav1 module. Modprobe it and plug in your camcorder. V4L should have handled the rest for you. If you are using KDE, fire open kdeTv and see if you can see yourself - obviously with the video cam plugged in.

rubadub · 10-25-2006, 05:26 AM

Cheers Phorem,

I'm not to sure how to remove said device, I can't find a 'rmnod' command, so i've 'rm''d it, rebooted, then 'modprobe' again. I still get the same errors when trying the python modules. Mplayer and Mencoder still work, i've not tried 'kdeTv' yet cos my yum is trippin out, i'll find and do manually, yet I think the prob still stands.

(Maybe prob still stands cos i've not removed my implimentation of the device properly yet?)

p.s. http://tldp.org/HOWTO/Webcam-HOWTO/ was where I got info from...

rubadub · 10-25-2006, 12:36 PM

Well I believe my prob with 'yum' is because fedora.com is down.

However, i've also tried scanimage:

Code:

$ scanimage -d v4l:/dev/video0 >o.pnm
scanimage: sane_start: Invalid argument

and the error is, but not sure why, i've tried many variations.

This might give extra info:

Code:

$ scanimage -L
device `v4l:/dev/video0' is a Noname Labtec Webcam virtual device

And i'm presuming that this shows the device is set up as a v4l device! So i'm throughly lost!