SYSTEM AND METHOD FOR ENHANCING AUDIO QUALITY FOR IP BASED SYSTEMS USING AN AMR PAYLOAD FORMAT

摘要

A method of enhancing audio quality for Internet protocol (IP) based systems using an adaptive multi-rate (AMR) payload format is presented. If a network buffer indicative of network congestion exceeds its threshold a determination is made whether to place a NO DATA frame into the current RTP packet instead of the AMR frame. If network conditions are too congested then a NO DATA frame is placed into the current RTP packet. The process is repeated for each incoming AMR frame. The process first ensures that the AMR coding rate is set to its lowest possible coding rate prior to substituting a AMR frame with a NO DATA frame. The substitution pattern is spread over the entire RTP packet to avoid clusters of NO DATA frames. The process can also single out AMR frames of lower energy value that would be good candidates for substitution.