For extracting GOG Captain Blood Ogg audio files

gog_captain_blood_extract_ogg.sh

#!/bin/bash

# Rough script for extracting Ogg/Vorbis audio files from *.ssb sound banks
# in Captain Blood found in <game_dir>/resource/sounds
#
# Usage: gog_captain_blood_extract_ogg.sh <bank_file>.ssb
#
# Uses ripgrep (rg)

# Notes:
#
#   1. Music themes are found in globals.ssb from index 057 to 127.
#      Extracted example - main menu theme: globals_126.ogg
#      Same theme is found in mini.ssb
#
#   2. without ripgrep, similar result can be achieved with grep like this (but it's much slower)
#      grep --only-matching --byte-offset --binary --text --perl-regex <header> <source>
# 
#   3. It's very basic and isn't trying to extract audio format according to the spec, it simply
#      splits things when detecting the beginning of the Ogg header. So it mostly works for audio
#      files placed back to back in the bank, but can produce incorrect data for some other cases.

source="$1"
source_size=$(stat -c %s "$source")
header='OggS\x00\x02'

offsets=( $(rg --no-line-number --only-matching --byte-offset --text  "$header" "$source" | cut -d : -f 1) )
# setting the last offset to the size of the file
offsets[${#offsets[@]}]=$source_size
num_files=$(( ${#offsets[@]} - 1 ))

for ((i = 0; i < $num_files; i++)); do
   left=${offsets[$i]}
   right=${offsets[$((i+1))]}
   
   idx=$(printf "%.${#num_files}u" $i) # nicely 0 prefixed index
   dd if="$source" of="${source%.*}_${idx}.ogg" skip=${left}B count=$(($right - $left))B bs=64M
done