V4L: "cat /dev/video0: no such device"; to be sure not supported?

jago25_98 · 01-27-2005, 02:27 AM

Where is the best place to get help getting Video for Linux (V4L) working for my USB webcam? (ALI M5603C)

I think the driver may be under development at the moment but how can I be sure with device nodes? How can I be sure that I've got everything right and that the device node is not there simply because it isn't supported? see here

I can create the device nodes but it says `device not found`. I have no /dev/v4l or /dev/video* without me making them.

Code:

root@ethel:~ # lsusb              
Bus 004 Device 003: ID 0402:5603 ALi Corp.

root@ethel:~ # ls /dev/v*
/dev/vcs   /dev/vcs2  /dev/vcs4  /dev/vcs6  /dev/vcsa   /dev/vcsa2  /dev/vcsa4  /dev/vcsa6  /dev/video0
/dev/vcs1  /dev/vcs3  /dev/vcs5  /dev/vcs7  /dev/vcsa1  /dev/vcsa3  /dev/vcsa5  /dev/vcsa7

root@ethel:~ # cat /dev/video0
cat: /dev/video0: No such device

root@ethel:~ # uname -a
Linux ethel 2.6.8.1-4-386 #1 Fri Jan 14 11:19:34 UTC 2005 i686 GNU/Linux

root@ethel:~ # lsmod
Module                  Size  Used by
nls_cp437               6016  0 
isofs                  33976  0 
udf                    79876  0 
sn9c102                48392  0  <-- this is the right module, but not sure if supported
...

$cat /prov/bus/usb/devices

...
T:  Bus=04 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=0402 ProdID=5603 Rev= 1.02
S:  Product=ALI M5603C
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=01(Isoc) MxPS=   0 Ivl=1ms
E:  Ad=82(I) Atr=03(Int.) MxPS=   0 Ivl=4ms
I:  If#= 0 Alt= 1 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=01(Isoc) MxPS=1023 Ivl=1ms
E:  Ad=82(I) Atr=03(Int.) MxPS=  16 Ivl=4ms
I:  If#= 0 Alt= 2 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=01(Isoc) MxPS= 900 Ivl=1ms
E:  Ad=82(I) Atr=03(Int.) MxPS=  16 Ivl=4ms
I:  If#= 0 Alt= 3 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=01(Isoc) MxPS= 384 Ivl=1ms
E:  Ad=82(I) Atr=03(Int.) MxPS=  16 Ivl=4ms
...

Electro · 01-27-2005, 04:04 PM

By typing ls -l /dev/video*. You should see the permissions and the major and minor. Some distributions have an symbolic link from /dev/video0...254 to /dev/v4l/video0...254. The major and minor should be for /dev/video0 is 81 for the major and 0 for the minor. The device type should be character for the device node. This is explained in devices.txt in the kernel documentation directory.

To make /dev/video0....254 to be used, you need videodev, v4l2-common (optional if the module needs it), and v4l1-compat (optional if running v4l2-common). You should see the directory video in /proc after you load videodev.

Your web cam will not capture frames fast enough because your USB speed is 12 Mbits designated by SPD from the information gathered at /prov/bus/usb/devices.

If you can not get it working, I suggest using a PCI video capture card because it is better than web cams and you can do a lot with them than a web cam.