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#!/bin/bash
# Analysis of obfsuscated KoTOR II audio
#
# *** Stock mp3 encoded with lame
# position of LAME : 0x09c (156)
# position of Info : 0x024 (36)
#
# *** KoTOR II obfuscated audio (using bed_001ebo.wav)
# position of LAME : 0xc7 (199)
# position of Xing : 0x4f (79)
#
# *** Conclusion:
# Xing should match to Info, but position of Xing
# is different in different obfuscated files.
#
# Note: Some files don't have Xing, and should be handled individually.
# mus_kriea.wav - uses regular Info instead of Xing
# mus_s_kreiaevil.wav - uses regular Info instead of Xing
# mus_a_main.wav - uses regular Info instead of Xing
# mus_a_kreiadark.wav - uses regular Info instead of Xing
# bed_950mal.wav - weird case (neither Xing nor Info).
# Chop off 58 bytes, similar to KoTOR I.
# *** Fixing method (for Xing/Info case):
# 1. Get position of first Xing/Info in the binary.
# 2. Chop everything before Xing/Info and Xing/Info itself (+4 after the position).
# 3. Prepend binary mp3 header to the result.
# Run from location where you have audio
# from the <game-dir>/StreamMusic directory.
# Make sure you have xxd hexdump tool installed.
function fix_with_header() {
local src="$1"
local offset="$2"
local target_tmp="fixed/${src%%.*}.tmp"
local target_mp3="fixed/${src%%.*}.mp3"
echo "fixing ${src} -> ${target_mp3}"
dd if=${src} of=${target_tmp} ibs=1 skip=${offset} obs=10M
cat ${header_file} ${target_tmp} > ${target_mp3}
rm ${target_tmp}
}
function fix_chop() {
local src="$1"
local offset="$2"
local target_mp3="fixed/${src%%.*}.mp3"
echo "fixing ${src} -> ${target_mp3}"
dd if=${src} of=${target_mp3} ibs=1 skip=${offset} obs=10M
}
hex_header='FFFB94640000000000000000000000000000000000000000000000000000000000000000496E666F'
header_file='fixed/header.hex'
mkdir -p fixed
echo $hex_header | xxd -r -p > $header_file
for src in *.wav; do
if [ "$src" == "bed_950mal.wav" ]; then
# No Xing or Info
fix_chop "$src" 58
else
match=$(grep --only-matching --byte-offset --binary --text "Xing" "$src")
if (($? != 0)); then
match=$(grep --only-matching --byte-offset --binary --text "Info" "$src")
if (($? != 0)); then
echo "Unknown case found: ${src}. Skipping."
continue
fi
fi
# Xing / Info case
offset=$(( $(echo "$match" | cut -d : -f 1) + 4 ))
fix_with_header "$src" $offset
fi
done
rm $header_file
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