multimonitor-screencast-capture.sh

#!/bin/bash
#
# Multi-monitor Screencast Capture for Linux
# 
# This script uses `ffmpeg` to simultaneously capture
# inputs:
#   - hd1080 monitor with "Slides" fullscreen
#   - hd1080 monitor "Demo" screen (usually terminal and/or browser)
#   - hd1080 webcam (h264)
#   - audio (aac)
#
# The monitor layout is set for:
#
# ${DISPLAY}+0,0              ${DISPLAY}+1920,0
#  +                           +
#  |                           |
#  v                           v
# ++------------------------+ ++-----------------------+
# |                         | |                        |
# |                         | |                        |
# |                         | |                        |
# |       "Demo"            | |      "Slides"          |
# |                         | |                        |
# |                         | |                        |
# |                         | |                        |
# |                         | |                        |
# +-------------------------+ +------------------------+
#
# To change this, edit the offsets used for the `x11grab` inputs in
# `capture_slides()` and `capture_demo()` below.
#
# The output is organized by `scene->shot->take` and saves files into
#
#     $(cwd)/
#       -> ${scene_name}/
#         -> shot-${shot_number}/
#           -> take-${timestamp}/
#             -> *.mkv
#
# Directories are created under the current directory as needed.
#
# Stop this manually with `Ctrl-c` when done
#
# Copyright and related rights waived via CC0

set -o errexit -o nounset -o pipefail

usage() {
        echo "Usage: $0 <scene_name> [<shot_number>]
    where:
      <scene_name> is something like intro-what-is-data-eng
      <shot_number> optional, default is 010"
}
(( $# < 1 )) && usage && exit 1
scene_name=$1
shot_number=${2:-010}

timestamp=`date +%Y-%m-%d-%H%M%S`
output_dir="${scene_name}/shot-${shot_number}/take-${timestamp}"
framerate=30
display=":0.0"

capture_slides() {
  local output_dir=$1
  ffmpeg \
    -hide_banner -nostats -loglevel warning \
    -f x11grab -r $framerate -s hd1080 -i ${display}+1920,0 \
    -vcodec libx264 \
    -preset ultrafast \
    $output_dir/slides.mkv > $output_dir/slides.log 2>&1
  echo "slides done"
}

capture_demo() {
  local output_dir=$1
  ffmpeg \
    -hide_banner -nostats -loglevel warning \
    -f x11grab -r $framerate -s hd1080 -i ${display}+0,0 \
    -vcodec libx264 \
    -preset ultrafast \
    $output_dir/demo.mkv > $output_dir/demo.log 2>&1
  echo "demo done"
}

capture_audio() {
  local output_dir=$1
  ffmpeg \
    -hide_banner -nostats -loglevel warning \
    -f alsa -i default \
    -c copy -copyts -start_at_zero \
    $output_dir/audio.wav > $output_dir/audio.log 2>&1
  echo "webcam done"
}

capture_webcam() {
  local output_dir=$1
  ffmpeg \
    -hide_banner -nostats -loglevel warning \
    -f v4l2 -framerate $framerate -input_format h264 -video_size hd1080 -ts mono2abs -i /dev/video0 \                                                                
    -c copy -copyts -start_at_zero \
    $output_dir/webcam.mkv > $output_dir/webcam.log 2>&1
  echo "webcam done"
}

echo "starting ${scene_name}/shot-${shot_number}/take-${timestamp}"
echo "Ctrl-c when done"

mkdir -p $output_dir

echo "capturing slides"
capture_slides $output_dir &

echo "capturing demo"
capture_demo $output_dir &

echo "capturing webcam"
capture_webcam $output_dir &

echo "capturing audio"
capture_audio $output_dir &

for job in `jobs -p`; do
  wait $job
done

echo "done"