from moviepy.editor import VideoFileClip

def extract_track(input_file, track_name, output_file):
    """
    Extracts a specific audio track from a multitrack MP4 file and saves it as a separate file.
    
    Parameters:
        input_file (str): The path to the input multitrack MP4 file.
        track_name (str): The name of the track to be extracted (e.g., 'vocals', 'drums', 'bass', 'other').
        output_file (str): The path to save the extracted track.
    
    Returns:
        None
    """
    try:
        clip = VideoFileClip(input_file)
        selected_track = clip.audio.subclip(0, clip.duration)
        selected_track.write_audiofile(output_file)
        clip.close()
        print(f"Track '{track_name}' extracted successfully and saved as '{output_file}'.")
    except Exception as e:
        print("An error occurred:", e)

# Example usage:
extract_track("path/to/multitrack_file.mp4", "vocals", "output_vocals.wav")