In the beginning of the file, there are 44 bytes, that tells you what length the file is, the frequency, bit sample rate, and channels. If the length doesn't match the files length, it will not work. The length is stored in two places, in &H100^x style so it's easy to retrieve them. The rest of the file doesn't matter what it contains, cuz it's 16bit or 8bit binary data which means all ascii are used.