Screen cast capturing script for X11 and Pulse/ALSA

With this script you can easily capture your screen including audio played by applications on a Linux distro currently using X11 and Pulse/ALSA.

Usage

$ ./capture.sh
Available audio devices:
    index: 1
    name: <alsa_output.pci-0000_00_10.3.analog-stereo>
Current audio device: alsa_output.pci-0000_00_10.3.analog-stereo.monitor (#0)
Tip: Change using 'pacmd set-default-sink SINK'
Device volume (%): 76
Screen size: 1920x1080
Output file: /home/myuser/capture-YYYYMMDD-HHMMSS.mkv
Select framerate [10]: 
Framerate: 10
Set video scaling (disable with 0) [720:-1]: 
Video scaling: 720:-1
Set audio scaling (disable with 0) [1]: 20
Audio scaling enabled: x20
Select constant rate factor [15]: 
Constant rate factor: 15
Select video codec [libx264]: 
Video codec: libx264
Select audio codec [aac]: 
Audio codec: aac
Select tune (0 to disable) [stillimage]: 
Tuning video for: stillimage

[Enter] Start recording  //  [Ctrl-C] Abort  //  [q] End recording

Requirements

• run on bash shell
• ffmpeg installed
• for recording without playback: module snd_aloop loaded
• pulse CLI available

Ubuntu 21.10 and higher

Select Ubuntu on XOrg during login in order to start GUI on X11 instead of unsupported Wayland, otherwise the script will fail with x11 needed.

Acknowledgements

• man ffmpeg-devices (x11grab, pulse)
• man ffmpeg-filters
• https://trac.ffmpeg.org/wiki/Capture/Desktop
• https://trac.ffmpeg.org/wiki/Capture/PulseAudio
• https://trac.ffmpeg.org/wiki/Limiting%20the%20output%20bitrate
• https://trac.ffmpeg.org/wiki/Encode/H.264
• https://stackoverflow.com/questions/39473434/ffmpeg-command-for-faster-encoding-at-a-decent-bitrate-with-smaller-file-size
• https://www.linuxquestions.org/questions/linux-desktop-74/ffmpeg-fails-cannot-open-display-0-0-error-1-a-4175613512/
• and other forums