record.sh

#!/usr/bin/env bash

declare file="$(date +%F-%s).webm"
declare window=false
declare region=false
declare duration
declare delay=0
declare verbose
declare -A dimensions

usage() {
  more <<'HELP'
'Usage: record [OPTIONS]
  -h  this help
  -f  specify file name [defaults to "$(date +%F-%s).webm"]
  -F  specify file name and overwrite if exists
  -d  specify duration
  -D  specify delay
  -w  select window
  -s  draw selectable region
  -v  show verbose output from ffmpeg'
HELP
}

err() {
  echo -e "\e[31m$1\e[0m" >&2
}

die() {
  if [[ -n "$1" ]]; then
    err "$1"
  fi
  exit 1
}

has() {
  command -v "$1" &> /dev/null
}

ask() {
  read -n1 -p "$* " ans
  echo
  [[ "${ans^}" == 'Y' ]]
}

delay() {
  for (( i=delay; i>0; --i )) ; do
    echo -ne "$i..                     \r"
    sleep 1
  done
  echo -ne "recording                \r"
}

getdimensions() {
  if [[ "$window" == true ]]; then
    local xwininfo x y w h
    echo -ne 'click a window\r'
    xwininfo=$(xwininfo)
    read -r x y w h < <(awk -F':' '/Absolute upper-left X/ { x=$2 }
      /Absolute upper-left Y/ { y=$2 }
      /Width/ { w=$2 }
      /Height/ { h=$2 }
      END { print x, y, w, h }' <<< "$xwininfo")
    dimensions=( ['x']="$x" ['y']="$y" ['w']="$w" ['h']="$h" )
  elif [[ "$region" == true ]]; then
    has xrectsel || die 'xrectsel required for -s'
    echo -ne 'select a region\r'
    #TODO: don't use eval
    eval "dimensions=( $(xrectsel "['x']='%x' ['y']='%y' ['w']='%w' ['h']='%h'") )"
  else
    scrsize=$(xdpyinfo | awk '/dimensions/{print $2}')
    dimensions=( ['x']='0' ['y']='0' ['w']="${scrsize%%x*}" ['h']="${scrsize#*x}" )
  fi
}

record-byzanz() {
  #TODO: remove byzanz altogether in favor of plain ffmpeg
  byzanz-record \
    --duration="${duration:-10}"\
    --x="${dimensions['x']}"\
    --y="${dimensions['y']}"\
    --width="${dimensions['w']}"\
    --height="${dimensions['h']}"\
    "$file" &&
  echo "saved as $file"
}

record-ffmpeg() {
  local loglevel size offset
  loglevel='panic'
  [[ -n $verbose ]] && loglevel='panic'
  size="${dimensions['w']}x${dimensions['h']}"
  offset="${DISPLAY}.0+${dimensions['x']},${dimensions['y']}"
  ffmpeg -y -loglevel "$loglevel" -f x11grab -s "$size" -i "$offset" ${duration:+-t $duration} \
    -c:v libvpx -crf 12 -s "$size" -b:v 1200k \
    -preset veryslow \
    -b 1000k -threads 4 \
    -f webm "$file" &&
  echo "saved as $file"
}

OPTERR=0
while getopts "f:F:d:D:swh" opt; do
  case "$opt" in
    f) file="$OPTARG"; overwrite=false ;;
    F) file="$OPTARG"; overwrite=true ;;
    w) window=true; region=false ;;
    s) window=false; region=true ;;
    v) verbose=true ;;
    d) duration="$OPTARG" ;;
    D) delay="$OPTARG" ;;
    h) usage; exit 0 ;;
  esac
done

[[ -z "$DISPLAY" ]] && die 'could not grab DISPLAY'

if [[ -f "$file" && "$overwrite" == false ]] && ! ask "overwrite ${file}? "; then
  die
fi

getdimensions
case "$file" in
  *gif)
    has byzanz-record || die 'need byzanz-record for recording gifs'
    delay
    record-byzanz ;;
  *webm)
    has ffmpeg || die 'need ffmpeg for recording webms'
    delay
    record-ffmpeg ;;
  *) die 'unknown file type, must be gif or webm' ;;
esac