Screencap

• 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.

Installation

Prerequisites

• 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.

Setup

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.

Syntax

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

Other tips

Editors

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

Sound not synchronizing

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 FFmpeg

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