convert-mod-track-to-video.sh

#!/bin/bash
#
# Record a video of a mod/s3m/xm tracker song played using milkytracker.
# 
# Dependencies with versions used in parenthesis:
#
#  schismtracker / milkytracker
#  pulseaudio
#  vnc2flv
#  turbovnc
#  ffmpeg

set -e -u -o pipefail

trap "trap - SIGTERM && kill -- -$$ && sleep 0.1 && kill -9 -- -$$" SIGINT SIGTERM 

debug()  { echo "$@" >&2; }

get_track_duration() { local file=$1 
  ffprobe -v quiet -show_format "$file" | grep "duration=" | cut -d"=" -f2 | sed "s/\..*$//"
}
 
get_metadata() { local file=$1
  ffprobe "$file" |& awk '/Metadata:/{flag=1;next}/Duration:/{flag=0}flag' | sed "s/^    //"
}

record_track() { local track=$@
  local duration output_dir info_file
  duration=$(get_track_duration $track)
  output_dir="output"
  mkdir -p "$output_dir"
  debug "Duration: $duration"
  info_file="$output_dir/$(basename "$track").txt"
  get_metadata "$track" > "$info_file"
  record_video "$output_dir" "$duration" "640x480" milkytracker -nosplash "$track"
  #record_video "$output_dir" "$duration" "640x480" schismtracker --classic --play "$track"
  echo "$info_file"
}

record_video() { local output_dir=$1 duration=$2 geometry=$3; shift 3; command=$@
  local display output_dir vnc_password video_file random
  local pid_xvnc pid_tracker pid_flvrec
  local pulse_sink pulse_source sink_index
  vnc_password="123123"
  random=$RANDOM
  display=":1"
  pulse_sink="vnc-$random"
  pulse_source="$pulse_sink.monitor"

  # Setup Pulseaudio
  sink_index=$(pactl load-module module-null-sink sink_name=$pulse_sink \
    sink_properties=device.description=$pulse_sink)
  pacmd load-module module-loopback sink=$pulse_sink >&2
  
  # Start VNC server
  echo "$vnc_password" | tightvncpasswd -f > .vncpasswd
  Xvnc -rfbport 5901 $display -rfbauth .vncpasswd -geometry "$geometry" >&2 &
  pid_xvnc=$!
  sleep 2
  
  # Start GUI command
  DISPLAY=$display PULSE_SINK=$pulse_sink $command >&2 &
  pid_tracker=$!
 
  # Record video & audio
  flvrec.py -C "$geometry+0-0" -o "out-$random.flv" -r 30 -P <(echo "$vnc_password") \
    -S "PULSE_SOURCE=$pulse_source parecord out-$random.wav" $display >&2 &
  pid_flvrec=$!
  sleep $((duration + 1))
  #sleep 10

  # Stop all tasks
  kill -INT $pid_flvrec $pid_xvnc $pid_tracker || true
  sleep 0.1
  kill -TERM $pid_flvrec $pid_xvnc $pid_tracker || true
  wait
  
  pactl unload-module $sink_index >&2

  # Merge video and & video
  video_file="$output_dir/$(basename "$track").mp4"
  ffmpeg -i "out-$random.flv" -i "out-$random.wav" -filter:v "crop=640:400:0:0" -s "854x480" \
    -shortest -map 0:0 -map 1:0 -ss 0.2 -y "$video_file"
  rm -f "out-$random.flv" "out-$random.wav"

  echo "$video_file"
}

if test $# -new 1; then
  echo "Usage: $(basename $0) TRACK_FILE"
  exit 2
else
  record_track "$@"
fi