Method for optimising the bit rate of multimedia contents accessible by a plurality of user terminals connected to a radiocommunications network cell, said multimedia contents being stored in the form of a plurality of independent chunks on at least one multimedia contents server associated with at least one contents provider, characterised in that said bit rate management method comprises the following steps, implemented in a bit rate optimising device: • receiving (E201, E201') at least one request to obtain at least one file representing at least one available quality corresponding to a bit rate for at least one chunk of at least one of said multimedia contents, called a multimedia description file, said request being sent by at least one user terminal of said plurality of user terminals to access said at least one multimedia content; • obtaining (E202, E203) said at least one multimedia description file; • modifying said at least one multimedia description file on the basis of at least one piece of information representing a quality of delivery of said at least one multimedia content to the at least one user terminal, called information on quality of delivery, said modification comprising a sub-step of elimination, for at least one chunk of said at least one multimedia content, of at least one available quality corresponding to a bit rate higher than a preliminarily obtained average bit rate Q av, said sub-step of elimination being implemented when a maximum bit rate Q i max borne by said at least one user terminal is higher than said average bit rate Q av, said at least one eliminated available quality corresponding to a bit rate higher than said average bit rate Q av to which a margin Q diff is added, this margin Q diff being decremented at a subsequent implementation of said step of elimination, said modification delivering at least one modified multimedia description file; and • transmitting said at least one modified multimedia description file to said at least one user terminal in response to said at least one request. • receiving (E201, E201') at least one request to obtain at least one file representing at least one available quality corresponding to a bit rate for at least one chunk of at least one of said multimedia contents, called a multimedia description file, said request being sent by at least one user terminal of said plurality of user terminals to access said at least one multimedia content; • obtaining (E202, E203) said at least one multimedia description file; • modifying said at least one multimedia description file on the basis of at least one piece of information representing a quality of delivery of said at least one multimedia content to the at least one user terminal, called information on quality of delivery, said modification comprising a sub-step of elimination, for at least one chunk of said at least one multimedia content, of at least one available quality corresponding to a bit rate higher than a preliminarily obtained average bit rate Q av, said sub-step of elimination being implemented when a maximum bit rate Q i max borne by said at least one user terminal is higher than said average bit rate Q av, said at least one eliminated available quality corresponding to a bit rate higher than said average bit rate Q av to which a margin Q diff is added, this margin Q diff being decremented at a subsequent implementation of said step of elimination, said modification delivering at least one modified multimedia description file; and • transmitting said at least one modified multimedia description file to said at least one user terminal in response to said at least one request.