Method of selecting a coding format in a terminal of a communications system

1/ A method of selecting multimedia data coding formats in a communications system having at least two terminals suitable for exchanging multimedia data with each other, each terminal having a set of coding formats listing those formats which it is capable of processing on reception and those which it is capable of applying to multimedia data on transmission,

• wherein, prior to any exchange of multimedia data between two terminals of the communications system, the method comprises the following steps:
• at least one of the two terminals sends its set of coding formats to a server of the communications system that is itself in communication with means for converting the coding format of the multimedia data that is to be exchanged;
• if necessary to enable multimedia data exchange to take place, the server enlarges the or each set of coding formats received from one of said two terminals as a function of the conversion means available to it, and it sends the possibly enlarged set to the other one of said two terminals;
• and
• each terminal receiving an enlarged set from the other one of said two terminals selects a receive coding format from amongst those which it is capable of processing on reception and that the other one of said two terminals is capable of applying in transmission as listed in its enlarged set and/or a transmit coding format from amongst those which it is capable of applying in transmission and which the other one of said terminals is capable of processing in reception, as listed in its enlarged set.