#!/bin/bash

# Check if all required arguments are provided
if [ $# -lt 2 ]; then
    echo "Usage: $0 <file_list.txt> <output_file>"
    echo ""
    echo "Arguments:"
    echo "  <file_list.txt>  Text file containing a list of files to concatenate."
    echo "  <output_file>    Path to the output video file."
    echo ""
    echo "Example:"
    echo "  $0 file_list.txt output.mp4"
    echo ""
    echo "Notes:"
    echo "  - The <file_list.txt> must contain file paths in the following format:"
    echo "      file 'video1.mp4'"
    echo "      file 'video2.mp4'"
    echo "  - All files in the list must have the same codec, resolution, and frame rate."
    exit 1
fi

# Assign input arguments to variables
file_list=$1
output_file=$2

# Check if the file list exists
if [ ! -f "$file_list" ]; then
    echo "Error: The file list '$file_list' does not exist."
    exit 1
fi

# Run the ffmpeg command
ffmpeg -f concat -safe 0 -i "$file_list" -c copy "$output_file"

# Check if the ffmpeg command succeeded
if [ $? -eq 0 ]; then
    echo "Concatenation completed successfully. Output saved to '$output_file'."
else
    echo "Error: ffmpeg failed to concatenate the files."
    exit 1
fi