FAQ for xawtv 3.x

Note: Most of the questions and answers apply to both xawtv and motv.

• Q: xawtv doesn't start
• Q: xawtv doesn't show anything
• Q: xawtv starts fine now, but how do I use it?
• Q: can xawtv deinterlace?

Q: xawtv doesn't start

Start the application from a terminal window. That way you'll see any error messages printed by xawtv, which should help finding the problem. Common errors are:

open /dev/video0: No such device

The device doesn't exist. Means there is no driver module for the hardware loaded yet. Fix your hardware setup.

Major opcode of failed request: 144 (GLX)

That is a problem with OpenGL (GLX Extention). Probably a bug in your OpenGL setup. You can disable OpenGL as workaround, start xawtv with the -nogl command line switch to do that.

Q: xawtv doesn't show anything

xawtv supports a wide range of hardware. Chances are good that xawtv simply tries to talk to another device than you expect. That is a common problem with nvidia cards which have a video port (for nvidia's composite input maybe?). xawtv picks that one instead of the TV card by default.

Try "xawtv -hwscan" to get a list of devices xawtv is aware of. Every device you can ask xawtv to use has the command line option needed to do that listed in brackets. The first device in the list is the default which xawtv will use if no other device is specified on the command line. Example:

eskarina kraxel ~# xawtv -hwscan
This is xawtv-3.91, running on Linux/x86_64 (2.6.5-rc1)
looking for available devices
port 69-69                              [ -xvport 69 ]
    type : Xvideo, video overlay
    name : video4linux

port 70-70                              [ -xvport 70 ]
    type : Xvideo, video overlay
    name : video4linux

port 71-71
    type : Xvideo, image scaler
    name : ATI Radeon Video Overlay

/dev/video0: OK                         [ -device /dev/video0 ]
    type : v4l2
    name : BT878 video (Hauppauge (bt878))
    flags: overlay capture tuner 

/dev/video1: OK                         [ -device /dev/video1 ]
    type : v4l2
    name : Proteus Pro [philips reference 
    flags: overlay capture tuner 

Default device in that case is Xvideo port 69, which is a video port driven by the X-Server's v4l module. If I want xawtv speak directly to the WinTV card using the v4l2 API I'll have to start xawtv with the "-device /dev/video0" switch.

Q: xawtv starts fine now, but how do I use it?

xawtv comes with a bunch of unix manual pages as documentation, just type "man xawtv" in a terminal window to read it. All the important stuff (like the very useful keyboard shortcuts) is documented there. Reading it at least briefly is strongly recommended.

You might also check out motv, which is IMHO more userfriendly. It also has more functions available in a mouse-compatible way, so it is easier to explore without wading through the documentation first. Neverless it is a good idea to check out the manual page here as well.

Q: can xawtv deinterlace?

Yes. The deinterlace plugins from xaw-deinterlace.sf.net have been integrated into the xawtv source tree and are available in recent versions. It needs noticable CPU horsepower through, if you have a fast machine try this:

xawtv -c /dev/video0 -remote -global:filter "linear blend"

Several conditions must be meet to make deinterlace work:

• xawtv must talk directly to the device, the -c /dev/video0 switch in the command line above does that.
• xawtv must operate in grabdisplay mode. The -remote does that in the example, it effectively disables the overlay mode (was intented as hint for xawtv that it runs on a remote display, thats why the strange name). Switching xawtv into grabdisplay mode using the menu in the GUI or via config file works equally well.
• The deinterlace filter must be enabled. The last switch in the command line above does that. You can also put that a filter=linear blend line into the [global] section of the ~/.xawtv config file. There are a few more filters (deinterlace and others) available. motv has them all listed in a menu where you can easily try them interactively. xawtv has no GUI for that right now.

© Gerd Knorr