unixorn/tumult.plugin.zsh

#!/usr/bin/env bash
#
# screencap-stream
#
# Captures a stream of PNGs to a directory. If we find ffmpeg, we then render them to .mp4
#
# Copyright 2022, Joe Block <jpb@unixorn.net>

set -o pipefail
if [[ -n "$DEBUG_RAW_COMMANDS" ]]; then
  set -x
fi

function debug() {
  if [[ -n "$DEBUG" ]]; then
    echo "$@"
  fi
}

function fail() {
  printf '%s\n' "$1" >&2  ## Send message to stderr. Exclude >&2 if you don't want it that way.
  exit "${2-1}"  ## Return a code specified by $2 or 1 by default.
}

function has() {
  # Check if a command is in $PATH
  which "$@" > /dev/null 2>&1
}

# on_exit and add_on_exit from http://www.linuxjournal.com/content/use-bash-trap-statement-cleanup-temporary-files

# Usage:
#   add_on_exit rm -f /tmp/foo
#   add_on_exit echo "I am exiting"
#   tempfile=$(mktemp)
#   add_on_exit rm -f "$tempfile"

function on_exit()
{
  for i in "${on_exit_items[@]}"
  do
      eval "$i"
  done
}

function add_on_exit()
{
  local n=${#on_exit_items[*]}
  on_exit_items[$n]="$*"
  if [[ $n -eq 0 ]]; then
    trap on_exit EXIT
  fi
}

function retain_frames()
{
  debug "Retaining frames"
  if [[ $keep_frames == 'true' ]]; then
    if [[ -d "$target_d" ]]; then
      rsync "${SCRATCH_D}"/*.png "$target_d"
    else
      echo "$target_d is not a directory, skipping frame retention"
    fi
  fi
}

function scrub_scratch() {
  debug "Nuking scratch directory ${SCRATCH_D}"
  if [[ -n "$DEBUG" ]]; then
    rm -frv "${SCRATCH_D}"
  else
    rm -fr "${SCRATCH_D}"
  fi
}

function makemovie()
{
  if [[ -n "$E_NO_POST" ]]; then
    echo "$E_NO_POST"
    exit 1
  fi
  echo "Creating movie from frames in $SCRATCH_D"
  echo "You set the interval between frame captures to $interval, setting movie rate to ${hertz}hz"
  retain_frames
  echo "Stitching frames into an mp4..."
  ffmpeg -pattern_type glob -framerate "$hertz" \
    -i "${SCRATCH_D}/*.png" \
    -c:v libx264 \
    -r 30 \
    -pix_fmt yuv420p \
    -movflags +faststart \
    "$moviename"
}

function usage() {
  myname=$(basename "$0")
  echo "Usage:"
  echo "$myname takes the following options:"
  echo "    -i interval in seconds between frame captures. Fractions are acceptable."
  echo "    -k Keep captured frames as snapshots after processing"
  echo "    -o output movie name"
  echo "    -t target directory (only used if keepframes is set)"
}

# Set up a working scratch directory
SCRATCH_D=$(mktemp -d)

if [[ ! "$SCRATCH_D" || ! -d "$SCRATCH_D" ]]; then
  fail "Could not create temp dir"
fi

if ! has screencapture; then
  fail "Cannot find 'screencapture' in your PATH."
fi

# Parse CLI options
# shellcheck disable=SC2048,SC2086
OPTS=$(getopt kt:i:o: $*)
# shellcheck disable=SC2181
if [[ $? -ne 0 ]]; then
  usage
  exit 1
fi
# shellcheck disable=SC2086
set -- $OPTS

# Set reasonable default values
keep_frames=false
interval=0.05
moviename="$(pwd)/screencap.mp4"

if has ffmpeg; then
  echo "Found ffmpeg, will make a movie after screen frames are captured."
  add_on_exit makemovie
else
  echo "No ffmpeg found in PATH, forcing frame retention"
  keep_frames=true
  add_on_exit retain_frames
fi
add_on_exit scrub_scratch

while :; do
  case "$1" in
    -i)
      shift
      interval=$1
      debug "Set interval to $interval"
      shift
      ;;
    -k)
      keep_frames=true
      debug "Set keep_frames to $keep_frames"
      shift
      ;;
    -o)
      shift
      moviename=$1
      debug "Set moviename to $moviename"
      shift
      ;;
    -t)
      shift
      target_d=$1
      debug "Set target_d to $target_d"
      shift
      ;;
    --) shift;
      break
      ;;
  esac
done

raw="scale=0; 1 / $interval / 4" # Was too fast until I halved the speed as a fudge factor
hertz=$(bc <<< "$raw")

debug "hertz: $hertz"
debug "interval: $interval"
debug "keep_frames: $keep_frames"
debug "moviename: $moviename"
debug "target_d: $target_d"

if [[ $keep_frames == 'true' ]]; then
  debug "Keepframes is set, checking if $target_d is a directory"
  if [[ ! -d "$target_d" ]]; then
    E_NO_POST="$target_d is not a directory"
    exit 1
  fi
fi

if [[ -f "$moviename" ]]; then
  E_NO_POST="$moviename already exists, exiting."
  exit 1
fi

while :; do
  fname="${SCRATCH_D}/$(date +%s).png"
  echo "📸 $(date +%H:%M:%S) $fname"
  screencapture -x "$fname"
  sleep "$interval"
done