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— Written by Triangles on September 18, 2015 • updated on December 06, 2020 • ID 17 —
A solution that pleasantly works out of the box.
Record a video of your desktop — and whatever happens on it — is almost dead simple with FFmpeg. I'm using one of the latest versions (as of this writing), 4.1.6 on a Linux box (Debian). I will also be using PulseAudio as the audio framework and x11grab for capturing the video part.
The generic command:
ffmpeg -video_size [resolution] -framerate [framerate] -f x11grab -i :0.0 -f pulse -ac 2 -i [source] output.mkv
As you may see you need to know the resolution, the video frame rate and the audio source.
Let's start with the resolution. Type
xrandr to print a list of supported video modes. For example:
Screen 0: minimum 8 x 8, current 1366 x 768, maximum 32767 x 32767 LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm 1366x768 60.06*+ 1360x768 59.80 59.96 1024x768 60.00 800x600 60.32 56.25 640x480 59.94 DP1 disconnected (normal left inverted right x axis y axis) HDMI1 disconnected (normal left inverted right x axis y axis) VGA1 disconnected (normal left inverted right x axis y axis) VIRTUAL1 disconnected (normal left inverted right x axis y axis)
The first mode in the list is the highest, let's go with it.
pactl list sources will print a list of supported PulseAudio sources (i.e. inputs). In my case I get the following:
Source #0 State: SUSPENDED Name: alsa_output.pci-0000_00_1b.0.analog-stereo.monitor Description: Monitor of Built-in Audio Analog Stereo ... [many other infos here] ...
0 is the only one available in my system. That's good. You should always record audio from the Monitor source, which basically contains what you are hearing over your speakers.
The complete command, in my case, looks something like this:
ffmpeg -video_size 1366x768 -framerate 25 -f x11grab -i :0.0 -f pulse -ac 2 -i 0 output.mkv
A frame rate of 25 fps is a common choice that works best in most cases.