File type: Adaptive Multi-Rate Codec File
File Extension AMR
The Adaptive Multi-Rate Codec File identified by the AMC file extension is an audio (compressed) format developed by Sony Ericsson and is currently used by many third generation cellular phones for its voice recording functionalities which can be included in MMS messages. This audio format includes the ACELP (Algebraic Code Excited Linear Prediction) algorithm which was conceived to efficiently compress the audio generated by human speech.
The effectiveness of this format was recognized in October 1998 when it was adopted by the 3GPP as the standard codec for speech and has since become widely deployed in many UMTS and GSM based communication networks. This standard implements link adaptation for selecting any of the eight varying bit rates depending on the link conditions exhibited by each bit rate.
Due to the popularity gained by this audio codec format, various third party applications have been developed to convert the AMC file extension to other popular audio file variants like the MP3. It must be noted however, that this audio format was developed primarily to cater to human speech and may not be ideal for use with other audio types like music.
Open AMR File