• It can record and encode 1080p 30fps video realtime with a single CPU core and supports as many threads as you want (default 2)
• It records audio and allows you to save different audio sources to different audio tracks. This lets you edit microphone commentary separately from system audio.
• With multiple config files you can have drastically different recording settings for different purposes.
• Complex filters allow anything from rescaling to overlaying webcam in realtime.
• Pass -- as an option and the following options will be sent to the end of the FFmpeg command, for instance in order to stream to twitch.

• FFmpeg
  Note: FFmpeg must be compiled with certain options depending on what you want to use.
  Support for x11grab, libx264, filters, pthreads, pulseaudio. Give or take a few depending on your config
  So if yours doesn't work, try compiling one yourself.
• Bash
• By default it uses the Pulseaudio sound server but there's nothing stopping you from using something else.
• Compositing window managers tend to remove tearing.

1. Place the script somewhere in $PATH (I use ~/bin)
2. Place the screencap-rc folder wherever you want it (I use ~/.sc-rc)
3. Open the script, scroll down to line 58 and set config_folder to the location of your screencap-rc folder (In my case that would be config_folder="$HOME/.sr-rc". Don't leave a trailing slash.
4. Run the script with: screencap [preset] [options] filename
5. Press q to stop recording.
6. Create your own config files. The files in screencap-rc are heavily commented to show a few use cases.

usage: screencap [preset] [options] filename

PRESET:
  Name of a file in the folder:
    screencap-rc
  or absolute path to equivalent file. Default is:
    screencap-rc/default

OPTIONS:

  -h, --help
    Show this message

  -r, --fps
    Framerate in FPS

  -i, --input
    Input size in WxH or "window" to pick one with xwininfo

  -o, --output
    Output size.-1 is wildcard to maintain aspect ratio eg: `w=-1:h=720`
    or `default` for no scaling

  --blind
    Disable video recording

  --mute
    Disable audio recording

  -t, --threads
    Number of threads to use

  --
    Stop screencap receiving input and pass all following parameters to command

In my opinion blender with gimp and audacity outperforms all other linux video editing software.

Pulseaudio has a weird tendency to mix up 48khz and 44.1khz, in such a way that FFmpeg flags can't even un-screw it up. To fix this problem, you can edit /etc/pulse/daemon.conf and change or uncomment the default-sample-rate and/or alternate-sample-rate lines to get the sound back in sync.

Avconv's x11grab device is broken and doesn't support the -framerate option - this means that any dropped frames will result in the output being shifted by a small amount of time and eventually desync from the sound. This is why this script no longer supports avconv.

Compiling a custom FFmpeg if your package manager doesn't have a good one is not the hardest thing in the world. That said I'm not going to offer a massive instruction manual here, but instead the basic steps I use to get the git repo, configure it, and build it on my system (debian sid).

apt-get update
apt-get install git build-essential yasm libcdio-paranoia-dev libx264-dev libvpx-dev libvorbis-dev libtheora-dev libspeex-dev libschroedinger-dev librtmp-dev libpulse-dev libopus-dev libopenjpeg-dev libopencv-dev libmp3lame-dev libgsm1-dev libgnutls-dev libfrei0r-ocaml-dev
git clone https://github.com/FFmpeg/FFmpeg.git
cd FFmpeg
./configure --arch=amd64 --enable-pthreads --enable-libopencv --enable-librtmp --enable-libopenjpeg --enable-libopus --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-vaapi --enable-runtime-cpudetect --enable-libvorbis --enable-zlib --enable-swscale --enable-libcdio --enable-bzlib --enable-libdc1394 --enable-frei0r --enable-gnutls --enable-libgsm --enable-libmp3lame --enable-libpulse --enable-vdpau --enable-libvpx --enable-gpl --enable-x11grab --enable-libx264 --enable-filters --enable-libzmq
make -j4

The binary can now be found at FFmpeg/ffmpeg