Normalize FLAC header of your library

clean.sh

#!/bin/bash
padding_low_limit=256
padding_high_limit=8192
padding_setup=2044
seekpoint_interval_limit=20
seekpoint_setup=6s

for album in ./*/*/
do
  before_clean_disk_usage=$(du --max-depth=0 "$album" | awk '{print $1}')
  
  echo "Start cleaning $album"
  echo "  [1/6] Remove undesirable header blocks..."
  metaflac --remove --block-type=APPLICATION,PICTURE "$album"*.flac
  
  echo "  [2/6] Sort padding blocks..."
  metaflac --sort-padding "$album"*.flac
  
  echo "  [3/6] Merge padding blocks..."
  metaflac --merge-padding "$album"*.flac
  
  echo "  [4/6] Add or update Replay Gain..."
  metaflac --add-replay-gain "$album/"*.flac
  
  echo "  [5/6] Check and fix seektables..."
  for track in "$album"*.flac
  do
    seek_points_count=$(metaflac --list --block-type=SEEKTABLE "$track" | grep "seek points: " | awk -F ": " '{print $2}')
    duration=$(metaflac --show-total-samples --show-sample-rate "$track" | tr '\n' ' ' | awk '{print $1/$2}')
    seekpoint_interval=""
    if [ ! -z "$seek_points_count" ]
    then
	    seekpoint_interval=$(echo "$duration/$seek_points_count" |bc)
    fi
    
    if [ -z "$seekpoint_interval" ] || [ $seekpoint_interval -gt $seekpoint_interval_limit ]
    then
      echo "       Missing or not enough seekpoint for $track. Build new seektable..."
      metaflac --remove --block-type=SEEKTABLE "$track"
      metaflac --add-seekpoint=$seekpoint_setup "$track"
    fi
  done
  
  echo "  [6/6] Check and fix padding block..."
  for track in "$album"*.flac
  do
    padding_length=$(metaflac --list --block-type=PADDING "$track" | grep "length: " | awk '{print $2}')
    if [ -z "$padding_length" ] || [ $padding_length -lt $padding_low_limit ] || [ $padding_length -gt $padding_high_limit ]
    then
      echo "       Missing, not enough or too much padding for $track. Rebuild padding block..."
      metaflac --dont-use-padding --remove --block-type=PADDING "$track"
      metaflac --add-padding=$padding_setup "$track"
    fi
  done
  
  after_clean_disk_usage=$(du --max-depth=0 "$album" | awk '{print $1}')
  delta_disk_usage=$(echo "$before_clean_disk_usage-$after_clean_disk_usage" |bc)
  echo "End cleaning $album ($delta_disk_usage bytes free)"
done