[NTLUG:Discuss] Screen Shots

[Steve Baker]

David Ross wrote:
> I have a problem when taking a screen shot.If i have a movie on the screen 
> (Totem/Ogle/Mplayer) or TV (TVTime/XawTV) the screen shot ends up being a 
> blue box where the video should be as if there was no signal.
> Any suggestions?

I've also noticed that you can't get a screenshot from these programs, presumably
because they talk to the graphics hardware at a very low level.

However, you can (with a little hassle) get mplayer to save one or more frames
of video (eg from a DVD) as a single frame image if you know where within the
video it is.

First, snip out a section of video into a smaller file:

If, for example, your sample is on a DVD:

  Encode a section of video from a DVD into a short 'avi' file:

   eg:

     mencoder -dvd 1 -chapter 6 -ss 24 -frames 100  -o temp.avi -oac pcm -ovc lavc
              ^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^  ^^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^^
                Start encoding here    Save 100     File to     Output    Output
                (same options as for   frames       send the    audio     video
                mplayer)               of video     snippet to.

   Then convert that short section of video into separate files:

     mplayer -vo png temp.avi

...which will generate 00000001.png 00000002.png 00000003.png...etc.
Now you can step through those files (I use 'xv' in visual schnauzer
mode) and select the exact frame you want.

It's kinda messy though.  It would be nice to find a more direct way.

I use this to extract still frames from DVD's created by my Sony DVD
video camera.

---------------------------- Steve Baker -------------------------
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