code: private void decodeMandatoryHeader() throws IOException {
          byte[] magicBytes = new byte[8];
          file.readFully(magicBytes);
          if (!Arrays.equals(SmjpegMagic.MANDATORY_HEADER, magicBytes)) {
              throw new SmjpegParsingException("This is not a SMJPEG file");
          }
          int version = file.readInt();
          if (version != 0) {
              throw new SmjpegParsingException("Unknow version " + version);
          }
          this.clipLengthInMilliseconds = file.readInt();
      }
docs: /*
  8 bytes magic - "^@\nSMJPEG"
  Uint32 version = 0
  Uint32 length of clip in milliseconds