#!/bin/bash

# Display usage information when requested or when no arguments are provided
usage() {
    echo "Usage: $0 input.gif [speedup_factor]"
    echo "  speedup_factor: Factor by which to speed up the animation (default is 1)."
    echo "  -h or --h: Display this help message."
    exit 1
}

# Check if help is requested
if [[ $1 == "-h" || $1 == "--h" ]]; then
    usage
fi

# Validate parameters
if [[ $# -lt 1 ]]; then
    usage
fi

input_file="$1"
speedup="${2:-1}"  # Default to 1 if not provided
output_file="${input_file%.gif}.webm"

# Run ffmpeg command with the specified parameters
ffmpeg -i "$input_file" -vf "scale=512:512:force_original_aspect_ratio=decrease,fps=30,setpts=${speedup}*PTS" -pix_fmt yuva420p -b:v 512k "$output_file"

echo "Converted $input_file to $output_file with a speedup factor of $speedup."