how to convert to file encode from utf-8 to ASCII?

["??????????" <237825552 () qq com>]

In the readme.developer,it say that the developer should convert the source file encode into ASCII,but when i extract 
the compress file ,it's default file encode is utf-8,what should i do ?

___________________________________________________________________________
Sent via:    Wireshark-dev mailing list <wireshark-dev () wireshark org>
Archives:    http://www.wireshark.org/lists/wireshark-dev
Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev
             mailto:wireshark-dev-request () wireshark org?subject=unsubscribe