KDE4 built-in screencast for desktop recording

Date: 20 Aug, 2008
Posted by: admin
In: design, fonts & graphics|hints & tips|linux, open source & software

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Record your desktop

[I’ve written elsewhere about video screen capture (a.k.a. screencast) applications. This is KDE4 specific.]

If you’re using KDE4 and have found the screencast feature ( System Settings > Desktop > [All Effects] : Video Record) you’re probably wondering how to play the files it produces. By default (during your KDE4 session) when you toggle “Video Record” mode on and then off with Ctrl-Meta-V it drops a file called kwin_video1.cps into your home directory which none of my video player apps could read – mplayer complained about avisynth.dll, but this doesn’t appear to be the real problem. The file is in the format used by captury, just don’t ask me why.

Playback your KDE4 “Video Record” files

You’ll need a couple of things:

mplayer OR vlc (or anything that can play y4m, a.k.a YUV4MPEG2 files)
capseo (just apt-get install it, it provides cpsrecode)

Then, if you’ve a faster machine use:

cpsrecode -i kwin_video.cps -o - | mplayer -

On my Athlon 1.1GHz that doesn’t do anything. Instead I need to transcode the file first and then play it.

cpsrecode -i kwin_video1.cps -o kwin_video1.cps.y4m

Note that cpsrecode’s man page also gives the option to transcode to “Theora” (using switch “-c theora”) but this didn’t work for me initially, failing with

ERROR: Unsupported output codec: theora

I then tried installing ffmpeg and ffmpeg2theora, neither cpsrecode nor ffmpeg could do the conversion still. Though you could convert the raw output from the .y4m file if you wished using ffmpeg or mencoder or something (thanks to Harald Sitter for this line).

cpsrecode -i kwin_video1.cps -o - \
| mencoder - -o
kwin_video1.avi -ovc lavc -lavcopts vcodec=xvid:autoaspect=1

Hope that helps.

Update:

This doesn’t work at all for me on my main computer (a dual core athlon) running Kubuntu. I get the .cps files made but cpsplay isn’t finished:

user@localhost:~/Videos/screencasts$ cpsplay ./kwin_video2.cps
error: This piece of cursed code is under development!
Please use `cpsrecode movie.cps | mplayer -` to view your movie.

and cpsrecode doesn’t operate (don’t use their suggestted code either, it’s the wrong format, see the man page or read above). The test binary cpsinfo reports the file size and resolution information however:

media:             : ./kwin_video2.cps

video:
frame width      : 1680
frame height     : 1050
frame scale      : 0
fps hint         : 30

cursor
present          : likely

Seems “Video Record” is not yet ready for service. Wonder why .cps was chosen.

1 Response to "KDE4 built-in screencast for desktop recording"

1 | Recap: KDE4 video screen capture, use KDEnlive | flapjacktastic

January 8th, 2009 at 12:58 am

[…] Recap of: “KDE4 built-in screencast for desktop recording“. […]


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