fmtp Attribute
The fmtp attribute shown in the following tables takes the form:
a=fmtp:<amrParameter> <parameterValues>
amrParameter contains one of the AMR/AMR-WB RTP-specific parameters listed below.
channels crc interleaving max-red maxtime mode-change-capability mode-change-neighbor mode-change-period mode-set octet-align ptime robust-sorting
parameterValue: contains the value of the specified parameter.