How to record a screencast while making a presentation

General questions regarding Linux.

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How to record a screencast while making a presentation

Postby David Miller » Sat Oct 09, 2010 10:46 am

first use xrandr to mirror your screen onto the external vga port on your laptop
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xrandr --output LVDS --auto --output VGA --mode 800x600 --same-as LVDS

Since my screen is 1024x600, only the leftmost 800x600 gets sent out to the external vga port. This is nice because I have an area on my screen that is not projected.

recordmydesktop is a nice way to make a screencast.
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recordmydesktop -width 800 -height 600  --on-the-fly-encoding -fps 10 --no-frame -device hw:1,0

Note that the -device switch is used to record audio from the second sound card, in this case its my external usb microphone.

You will most likely want to cut something off the beginning and end, you can do this loselessly with oggCut, which is part of oggvideotools.
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oggCut -s 'start' -e 'end' out.ogv screencast.ogv

the start and end times are in milliseconds. Just watch your video in mplayer and see where you want the cuts to be.

once you have uploaded the file somewhere you can embed it with this html
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<video src="" controls>
<applet code="com.fluendo.player.Cortado.class" archive="" width="800" height="600">
<param name="url" value="" />

If your browser supports ogg, which firefox does, it will play via the <video> tag. If the browser doesn't support this, it will fallback to using a java ogg player.

David Miller

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