chd converter of redump dumps (dats from https://github.com/MetalSlug/MAMERedump). Hacks will not be recognized, if you place them in a subdir you can use --skip '*/Hacks/*' to skip a sub-directory if a tool has otherwise a method to get hack names (either by a dedicated dat or another trick like rxdelta files from my other tool rhdndat-rn).

chd-convert.sh

#!/bin/bash

# chd-convert.sh
#use a absolute path if you want a newer self compiled chdman
CHDMAN_PATH="chdman"
SEARCH_DIR="."
SKIP_DIRS=()
DRY_RUN=false
LOG_FILE="conversion.log"

# Counters
fail_count=0
success_count=0
total_saved_bytes=0
processed_count=0

usage() {
    echo "Usage: chd-convert.sh [options] [search_directory]"
    echo ""
    echo "Options:"
    echo "  -h, --help      Show help message"
    echo "  -s, --skip DIR  Dir glob to skip (can be used multiple times)"
    echo "  -d, --dry-run   Show what would be done without making changes"
    echo ""
    echo "Compression Codecs used:"
    echo "  CD:  cdzs,cdzl,cdfl (Zstandard, Deflate, FLAC)"
    echo "  DVD: zstd,zlib,huff (Zstandard, Deflate, Huffman)"
    exit 0
}

for cmd in "$CHDMAN_PATH" setfattr sha1sum awk sed find; do
    if ! command -v "$cmd" &> /dev/null; then
        echo "ERROR: Required command '$cmd' is not found."
        exit 1
    fi
done

# Parse Command Line Arguments
while [[ "$#" -gt 0 ]]; do
    case $1 in
        -h|--help) usage ;;
        -d|--dry-run) DRY_RUN=true ;;
        -s|--skip) SKIP_DIRS+=("$2"); shift ;;
        -*) usage ;;
        *) SEARCH_DIR="$1" ;;
    esac
    shift
done

# Initialize Log
> "$LOG_FILE"
shopt -s nullglob nocaseglob

status() {
    local prefix=""
    $DRY_RUN && prefix="[DRY-RUN] "
    echo -e "${prefix}$1" | tee -a "$LOG_FILE"
}

human_readable() {
    local bytes=$1
    if [ "$bytes" -lt 1024 ]; then echo "${bytes}B"
    elif [ "$bytes" -lt 1048576 ]; then echo "$((bytes/1024))KB"
    elif [ "$bytes" -lt 1073741824 ]; then echo "$((bytes/1048576))MB"
    else echo "$((bytes/1073741824))GB"
    fi
}

convert_game() {
    local source_file="$1"
    local chdman_mode="$2"
    local codec="$3"
    local parent_dir="${source_file%/*}"
    local output_chd="${source_file%.*}.chd"
    
    # Internal check: ensure source exists before proceeding
    if [ ! -f "$source_file" ]; then
        status "  ERROR: Source file \"$source_file\" no longer exists. Skipping."
        ((fail_count++))
        return 1
    fi

    status "Processing: $source_file"
    ((processed_count++))

    if [ -f "$output_chd" ]; then
        status "  Warning: Skipping, \"$output_chd\" already exists."
        return
    fi

    local cmd_args=("-c" "$codec")
    local total_source_size=$(stat -c%s "$source_file")
    local tracks=()

    # Unified track validation loop
    if [[ "$chdman_mode" == "createcd" ]]; then
        while read -r track_name; do
            local track_path=$([[ "$track_name" == /* ]] && echo "$track_name" || echo "$parent_dir/$track_name")
            if [ ! -f "$track_path" ]; then
                status "  ERROR: Required track file missing: \"$track_path\". Aborting."
                ((fail_count++))
                return 1
            fi
            tracks+=("$track_path")
            total_source_size=$((total_source_size + $(stat -c%s "$track_path")))
        done < <(sed -n 's/^[[:space:]]*FILE[[:space:]]\+"//p' "$source_file" | sed 's/"[[:space:]]\+[A-Z]\+[[:space:]]*$//')
    fi

    # PSP specific hunksize check
    if [[ "$chdman_mode" == "createdvd" ]] && head -c 500000 "$source_file" | grep -aqE "PSP[ _]GAME"; then
        status "  Note: PSP signature detected. Applying hunksize 2048."
        cmd_args+=("-hs" "2048")
    fi

    if $DRY_RUN; then
        status "  Would run: $CHDMAN_PATH $chdman_mode -i \"$source_file\" -o \"$output_chd\" ${cmd_args[*]}"
        ((success_count++))
    else
        if "$CHDMAN_PATH" "$chdman_mode" -i "$source_file" -o "$output_chd" "${cmd_args[@]}"; then
            local chd_size=$(stat -c%s "$output_chd")
            local saved_bytes=$((total_source_size - chd_size))
            local saved_percent=$(( 100 - (chd_size * 100 / total_source_size) ))
            total_saved_bytes=$((total_saved_bytes + saved_bytes))

            # Cleanup
            for track in "${tracks[@]}"; do rm -- "$track"; done
            rm -- "$source_file"
            
            status "  Success: Created $output_chd ($saved_percent% smaller, saved $(human_readable $saved_bytes))"
            ((success_count++))
        else
            status "  ERROR: chdman failed for $source_file"
            ((fail_count++))
        fi
    fi
}

# Construct find prune arguments
FIND_SKIP_ARGS=()
for skip in "${SKIP_DIRS[@]}"; do
    FIND_SKIP_ARGS+=(-path "$skip" -prune -o)
done

# Main Execution Loop
while IFS= read -r -d '' unique_dir; do
    for f in "$unique_dir"/*.cue; do 
        convert_game "$f" "createcd" "cdzs,cdzl,cdfl"
    done
    for f in "$unique_dir"/*.iso; do 
        convert_game "$f" "createdvd" "zstd,zlib,huff"
    done
done < <(find "$SEARCH_DIR" "${FIND_SKIP_ARGS[@]}" -type f \( -iname "*.cue" -o -iname "*.iso" \) -printf "%h\0" | sort -zu)

# Final Summary
status "-----------------------------------"
status "Finished!"
status "Successful: $success_count | Failures: $fail_count"
if ! $DRY_RUN && [ "$processed_count" -gt 0 ]; then
    status "Total space saved: $(human_readable $total_saved_bytes)"
fi

[ "$processed_count" -eq 0 ] && rm "$LOG_FILE"