A method for automatically characterizing non-linearities of a perpendicular read-back signal of a recording system is disclosed. The delay equalizer equalizes an FL signal using an equalizer characteristic EQ9 that converts a characteristic of an audio signal perceived as being reproduced at a position of an FL speaker with respect to a viewing position to be perceived as being reproduced at a position of a virtual speaker with respect to the viewing position. The message is transmitted to a terminal in a system for transmitting multimedia messages.