哪种方式更好？将媒体文件以字节数组或字符串形式保存到MongoDB？

I'm saving media files (pictures, PDFs, etc.) in MongoDB as array of bytes. I saw examples where people saved it by Encoding and Decoding array of bytes to string. What is the difference? Maybe difference in performance? So which way is better? I'm saving media files (pictures, PDFs, etc.) i