I use Ubuntu 6.06- kernek 2.6.15.27, and I'm trying to use an external video capture card, hoping that Linux can be slighty faster than Windows and I can get videos without missing frames.

Obviously, the manufacturer gives no specification chipset, so I tried to plug it in and read what dmesg says:

[17183899.560000] usb 5-2.3: new high speed USB device using ehci_hcd and address 6
[17183899.852000] Linux video capture interface: v1.00
[17183899.872000] em28xx v4l2 driver version 0.0.1 loaded
[17183899.872000] em28xx new video device (eb1a:2820): interface 0, class 255
[17183899.872000] em28xx: Alternate settings: 8
[17183899.872000] em28xx: Alternate setting 0, max size= 0
[17183899.872000] em28xx: Alternate setting 1, max size= 1024
[17183899.872000] em28xx: Alternate setting 2, max size= 1448
[17183899.872000] em28xx: Alternate setting 3, max size= 2048
[17183899.872000] em28xx: Alternate setting 4, max size= 2304
[17183899.872000] em28xx: Alternate setting 5, max size= 2580
[17183899.872000] em28xx: Alternate setting 6, max size= 2892
[17183899.876000] em28xx: Alternate setting 7, max size= 3072
[17183899.900000] saa711x: Ignoring new-style parameters in presence of obsolete ones
[17183900.920000] em28xx #0: V4L2 device registered as /dev/video0
[17183900.920000] em28xx #0: Found MSI VOX USB 2.0
[17183900.920000] usbcore: registered new driver em28xx
[17191633.228000] usb 5-2.3: USB disconnect, address 6
[17191633.228000] em28xx #0: disconnecting em28xx video
[17191633.228000] em28xx #0: V4L2 device /dev/video0 deregistered
[17191659.304000] usb 5-2.3: new high speed USB device using ehci_hcd and address 7
[17191659.412000] em28xx new video device (eb1a:2820): interface 0, class 255
[17191659.412000] em28xx: Alternate settings: 8
[17191659.412000] em28xx: Alternate setting 0, max size= 0
[17191659.412000] em28xx: Alternate setting 1, max size= 1024
[17191659.412000] em28xx: Alternate setting 2, max size= 1448
[17191659.412000] em28xx: Alternate setting 3, max size= 2048
[17191659.412000] em28xx: Alternate setting 4, max size= 2304
[17191659.412000] em28xx: Alternate setting 5, max size= 2580
[17191659.412000] em28xx: Alternate setting 6, max size= 2892
[17191659.412000] em28xx: Alternate setting 7, max size= 3072
[17191660.388000] em28xx #0: V4L2 device registered as /dev/video0
[17191660.388000] em28xx #0: Found MSI VOX USB 2.0

So it seems to be seen by the system.

Then I tried to see something usin xawtv, but it said v4l-conf had some problem, so i get this from v4l-conf:

v4l-conf: using X11 display :0.0
dga: version 2.0
mode: 1280x1024, depth=24, bpp=32, bpl=5120, base=0xc8000000
/dev/video0 [v4l2]: no overlay support

I don't know if this means no stream can be read, my knowledge in this is small.

Oh, I forgot to say that xawtv opened without no image in it.

I tried mplayer in this way:
mplayer tv:// -tv driver=v4l2:device=/dev/video0

And I get this:

MPlayer 2:0.99+1.0pre7try2+cvs20060117-0ubuntu8 (C) 2000-2006 MPlayer Team
CPU: Advanced Micro Devices Athlon Thunderbird (Family: 6, Stepping: 2)
CPUflags: MMX: 1 MMX2: 1 3DNow: 1 3DNow2: 1 SSE: 0 SSE2: 0
Compiled with runtime CPU detection.


91 audio & 204 video codecs
# This seem to be the problem
Linux RTC init error in ioctl (rtc_irqp_set 1024): Permission denied
Try adding "echo 1024 > /proc/sys/dev/rtc/max-user-freq" to your system startup scripts.
# but I don't know what happen if I follow the suggestion

#My card has no remote control and no TV tuner, so I think the following is ok
Opening joystick device /dev/input/js0
Can't open joystick device /dev/input/js0: No such file or directory
Can't init input joystick
Setting up LIRC support...
mplayer: could not connect to socket
mplayer: No such file or directory
Failed to open LIRC support.
You will not be able to use your remote control.
#
Playing tv://.
Selected driver: v4l2
name: Video 4 Linux 2 input
author: Martin Olschewski <olschewski@zpr.uni-koeln.de>
comment: first try, more to come ;-)
Selected device: MSI VOX USB 2.0
Tuner cap:
Tuner rxs:
Capabilites: video capture tuner audio read/write streaming
supported norms: 0 = PAL; 1 = NTSC; 2 = SECAM; 3 = PAL-M;
inputs: 0 = Television; 1 = Composite1; 2 = S-Video;
Current input: 0
Current format: YUYV
v4l2: current audio mode is : MONO
v4l2: ioctl query control failed: Invalid argument
==========================================================================
Opening video decoder: [raw] RAW Uncompressed Video
VDec: vo config request - 640 x 480 (preferred colorspace: Packed YUY2)
VDec: using Packed YUY2 as output csp (no 0)
Movie-Aspect is undefined - no prescaling applied.
VO: [xv] 640x480 => 640x480 Packed YUY2
Selected video codec: [rawyuy2] vfm: raw (RAW YUY2)
==========================================================================
Audio: no sound
Starting playback...
V: 0.0 16/ 16 ??% ??% ??,?% 0 0
#after a while, with a green MPlayer window stilling there, I hitted CTRL-C
MPlayer interrupted by signal 2 in module: video_read_frame

#another CTRL-C
MPlayer interrupted by signal 2 in module: free_demuxer

I've stopped, because both of my UNknowledge of video in general and VideoForLinux in particular.
Now I don't know if there is a wrong codec, or my card is simply unsupported, or I made a mess with mencoder or xawtv, or I should simply follow the hint of mencoder.

Also, I wondered a while if I should post this in Hardware or Software forum, because I don't know where the problem belongs.

Thanks for any hint.

If you follow the suggestion you bolded, it will adjust the userspace ability to get to the system's rtc (real time clock). This should be helpful to getting it to work.

What particular device are you using?

Matir,

before all, thanks for the answer.
Forgive me for the late in response, I've not always the access to Internet.
I'm using a small external device called "video grabber", that accepts in input an RCA or a composite signal, and giving in output audio on a common stereo jack, and video on USB.
I bought it with the goal of transfer my VHSs on DVDs, and to get TV signal via my digital decoder, both using an adapter(SCART->RCA).
The brand is Empire, the device is named "DVD Video Grabber USB 2.0", also if I know that this means nothing, but just to give an idea of the type of device it is.
The main problem in understanding what to do was that the manufacturer gave no information on the kind of output the device gives via USB, teaching only to install the bundled program, connect the device, set up the drivers, and use the program. Searching "video capture" or "video grabbing" gave me hints on TV cards that were able to tune on different channels, or on cards that use FireWire interface to connect to VCR, and I wasn't able to detect what and where those hints apply in my case.
So I tried to feed it to my Linux (Ubuntu 6.06) hoping that it could understand it better than me, and seems that v4l read something and can get many informations correctly, but then I stopped were I wrote before.

A question about your answer: do you think there is a specifical optimal place to put the suggested line? Or should I put it in a standalone file?

Thanks in advance.

P.S. I'll try however to find a place to put it, and will report what will happen.