mp4_to_m4a.sh

#!/bin/bash
set -euo pipefail

# --- Helper: detect package manager ---
detect_pkg_mgr() {
    if command -v apt-get &>/dev/null; then echo "apt-get"
    elif command -v yum &>/dev/null; then echo "yum"
    elif command -v dnf &>/dev/null; then echo "dnf"
    elif command -v pacman &>/dev/null; then echo "pacman"
    elif command -v zypper &>/dev/null; then echo "zypper"
    else echo "unknown"; fi
}

# --- Helper: ensure a command exists ---
ensure_command() {
    local cmd="$1"; local pkg="$2"
    if command -v "$cmd" &>/dev/null; then return 0; fi
    echo "$cmd not found. Attempting to install..."
    PKG_MGR="$(detect_pkg_mgr)"
    case "$PKG_MGR" in
        apt-get) sudo apt-get update && sudo apt-get install -y "$pkg" ;;
        yum) sudo yum install -y "$pkg" ;;
        dnf) sudo dnf install -y "$pkg" ;;
        pacman) sudo pacman -Sy --noconfirm "$pkg" ;;
        zypper) sudo zypper install -y "$pkg" ;;
        *) echo "Could not detect package manager. Please install $cmd manually." >&2; exit 1 ;;
    esac
}

# Ensure ffmpeg exists
ensure_command ffmpeg ffmpeg

# Detect CPU count
if command -v nproc &>/dev/null; then
    MAX_PROCS=$(nproc)
elif [ -f /proc/cpuinfo ]; then
    MAX_PROCS=$(grep -c '^processor' /proc/cpuinfo)
else
    MAX_PROCS=4
fi
echo "Using $MAX_PROCS parallel jobs."

# Output directory (absolute path)
CONVERTED_DEST="$(pwd)/m4a_outputs"
mkdir -p "$CONVERTED_DEST"
echo "Output directory: $CONVERTED_DEST"

# Create log directory
LOG_DIR="$(pwd)/conversion_logs"
mkdir -p "$LOG_DIR"
echo "Log directory: $LOG_DIR"

# Find MP4 files first
echo "Searching for MP4 files..."
MP4_FILES="$(mktemp)"
find "." -type f -iname '*.mp4' > "$MP4_FILES"

FILE_COUNT=$(wc -l < "$MP4_FILES")
if [ "$FILE_COUNT" -eq 0 ]; then
    echo "No MP4 files found in current directory and subdirectories."
    rm -f "$MP4_FILES"
    exit 0
fi

echo "Found $FILE_COUNT MP4 files to convert:"
cat "$MP4_FILES"
echo "===================="

# Create results file
RESULTS="$(mktemp)"

echo "Starting parallel conversion..."

# Process files with better parallel handling
echo "Using xargs for processing..."

# Create a wrapper script for the function
WRAPPER_SCRIPT="$(mktemp)"
cat > "$WRAPPER_SCRIPT" << 'EOF'
#!/bin/bash
file="$1"
CONVERTED_DEST="$2"
LOG_DIR="$3"

filename="$(basename "$file")"
base="${filename%.*}"
out="$CONVERTED_DEST/${base}.m4a"
log_file="$LOG_DIR/${base}.log"

echo "[$(date '+%Y-%m-%d %H:%M:%S')] Starting: $file" | tee -a "$log_file"

# Check if input file exists and is readable
if [ ! -f "$file" ]; then
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] ERROR: Input file not found: $file" | tee -a "$log_file"
    echo "FAIL:$file:File not found"
    exit 1
fi

# Run ffmpeg with full logging
echo "[$(date '+%Y-%m-%d %H:%M:%S')] Converting: $file -> $out" | tee -a "$log_file"
echo "[$(date '+%Y-%m-%d %H:%M:%S')] Running: ffmpeg -i \"$file\" -vn -c:a aac -b:a 192k -y \"$out\"" | tee -a "$log_file"

if ffmpeg -i "$file" -vn -c:a aac -b:a 192k -y "$out" 2>&1 | tee -a "$log_file"; then
    if [ -f "$out" ] && [ -s "$out" ]; then
        local size=$(stat -f%z "$out" 2>/dev/null || stat -c%s "$out" 2>/dev/null || echo "unknown")
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ✅ SUCCESS: $file -> $out (size: ${size} bytes)" | tee -a "$log_file"
        echo "OK:$file:$out:$size"
    else
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ❌ FAILED: Output file is empty or missing: $out" | tee -a "$log_file"
        echo "FAIL:$file:Output file empty or missing"
    fi
else
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] ❌ FAILED: ffmpeg error for $file" | tee -a "$log_file"
    echo "FAIL:$file:ffmpeg error"
fi
EOF

chmod +x "$WRAPPER_SCRIPT"

# Process files using the wrapper script
cat "$MP4_FILES" | head -5 | xargs -I {} -P "$MAX_PROCS" -n 1 "$WRAPPER_SCRIPT" {} "$CONVERTED_DEST" "$LOG_DIR" > "$RESULTS" 2>&1

# Clean up wrapper script
rm -f "$WRAPPER_SCRIPT"

echo "Conversion jobs completed. Analyzing results..."

# Count results and show detailed summary
SUCCESS=0
FAILED=0

echo ""
echo "=== CONVERSION SUMMARY ==="
while IFS=: read -r status file rest; do
    case "$status" in
        "OK")
            SUCCESS=$((SUCCESS + 1))
            echo "✅ $file"
            ;;
        "FAIL")
            FAILED=$((FAILED + 1))
            echo "❌ $file ($rest)"
            ;;
    esac
done < "$RESULTS"

echo ""
echo "=== FINAL RESULTS ==="
echo "Successfully converted: $SUCCESS"
echo "Failed conversions: $FAILED"
echo "Total processed: $((SUCCESS + FAILED))"

# Show output directory contents
echo ""
echo "=== OUTPUT DIRECTORY CONTENTS ==="
if [ -d "$CONVERTED_DEST" ]; then
    ls -la "$CONVERTED_DEST"/ || echo "Directory is empty"
else
    echo "Output directory does not exist!"
fi

echo ""
echo "=== LOG FILES ==="
if [ -d "$LOG_DIR" ]; then
    echo "Conversion logs available in: $LOG_DIR"
    ls -la "$LOG_DIR"/ || echo "No log files found"
    
    # Show last few lines of failed conversions
    if [ "$FAILED" -gt 0 ]; then
        echo ""
        echo "=== SAMPLE ERROR LOGS ==="
        for logfile in "$LOG_DIR"/*.log; do
            if [ -f "$logfile" ] && grep -q "FAILED\|ERROR" "$logfile"; then
                echo "--- Last 10 lines of $(basename "$logfile") ---"
                tail -10 "$logfile"
                echo ""
            fi
        done
    fi
else
    echo "Log directory does not exist!"
fi

# Cleanup temp files
rm -f "$MP4_FILES" "$RESULTS"

echo "All outputs are in: $CONVERTED_DEST"
echo "All logs are in: $LOG_DIR"