ffmpeg.sh

probe () {
  ffprobe -v error -show_entries $1 -of default=noprint_wrappers=1:nokey=1 $2
}

get_bitrate (){
  original=$1
  filesize=$2
  max_audio_bitrate=${3:-64000}
  seconds=`probe format=duration $original`
  total_bitrate=`echo "scale=0; (8 * $filesize/$seconds)" | bc`  # filesize in byte, bitrate in bit
  bitrate=`python3 -c "import sys; sys.stdout.write(str(max($total_bitrate - $max_audio_bitrate, $total_bitrate * 3 // 4))); sys.stdout.flush()"`  # filesize in byte, bitrate in bit
  audio_bitrate=`echo "scale=0; ($total_bitrate - $bitrate)" | bc`
  file_size=`echo "scale=2; ($total_bitrate * $seconds / 8 / 1024 / 1024)" | bc`
  echo $bitrate $audio_bitrate

  # echo
  # echo "Encoding $seconds seconds of video with"
  # echo "    Video Bitrate: $bitrate"
  # echo "    Audio Bitrate: $audio_bitrate"
  # echo "    Total Bitrate: $total_bitrate"
  # echo "Final file should be around $file_size MiB"
  # echo

}

get_scale (){
  original=$1
  target_width=$2
  width=`probe stream=width $original`
  height=`probe stream=height $original`
  python3 -c "import sys; width=min($width, $target_width); sys.stdout.write(f'{width}:{int(width/$width*$height):d}'); sys.stdout.flush()"
}

encode () {
  original=$1
  format=$2
  codec=$3
  args=$4
  width=$5
  filesize=${6:-8000000}  # default: 8MByte - 5% overhead | otherwise specified value
  echo $original $filesize

  rates=`get_bitrate $original $filesize 64000`
  echo $rates
  rates=($rates)
  echo $rates
  bitrate=${rates[0]}
  audio_bitrate=${rates[1]}
  echo $bitrate $audio_bitrate

  scale=`get_scale $original $width`

  ffmpeg -hide_banner -y -i $original -vf "fps=film:round=near,scale=$scale" -c:v $codec $args -b:v $bitrate -pass 1 -an -f $format /dev/null
  ffmpeg -hide_banner -y -i $original -vf "fps=film:round=near,scale=$scale" -c:v $codec $args -b:v $bitrate -pass 2 -c:a libopus -b:a $audio_bitrate -movflags +faststart -fflags +genpts out.$format
}

encodecrf () {
  original=$1
  format=$2
  codec=$3
  crf=$4
  args=$5
  audio_bitrate=96000
  new_name=`python3 -c "import sys; sys.stdout.write('.'.join('$original'.split('.')[:-1]) + '_reencode.$format')"`
  ffmpeg -hide_banner -y -i $original -crf $crf -c:v $codec $args -c:a libopus -b:a $audio_bitrate -movflags +faststart -fflags +genpts $new_name
}


encodecrfh265 () {
  encodecrf $1 mp4 libx265 $2 "-preset slow"
}

encodecrfh264 () {
  encodecrf $1 mp4 libx264 $2 "-preset slow"
}

encodecrfav1 () {
  encodecrf $1 webm libaom-av1 $2 "" $3
}

encodemp4 (){
  encode $1 mp4 libx264 "-preset veryslow" $2 $3
}
encodeav1 (){
  encode $1 webm libaom-av1 "" $2 $3
}
encodevp9 (){
  encode $1 webm libvpx-vp9 "" $2 $3
}


download (){
  url=$1
  width=${2:-640}
  size=${3:-8000000}
  tmp="/tmp/.temp.webm"
  yt-dlp $url --output $tmp
  if [ -f $tmp ]; then
      echo
  else
      tmp="${tmp}.mp4"
  fi
  echo "Using $tmp as temporary file"
  encodevp9 $tmp $width $size
  rm $tmp
}