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AMR, Adaptive Multi-Rate Audio File (.amr)

 

The .amr file format

The Adaptive Multi-Rate (AMR) codec is an audio compression format enhanced for speech coding. It is also a file format for holding audio speech via the AMR codec. Storage of short audio recordings in the AMR format is a feature common to numerous modern mobile handsets and either free or patented programs exist for conversion between these formats.

 

.amr technical details

AMR speech codec is made up of a multi-rate speech codec in narrowband (200–3400 Hz) that encodes these types of signals at variable bit rates ranging between 4.75 to 12.2 kbit/s with toll quality audio (comparable to that of an ordinary long distance call) starting at 7.4 kbit per second. AMR is now widely used in GSM[4] and UMTS, having been adopted as the standard speech codec in October 1999 by 3GPP . Using link adaptation it is able to choose from one of eight different bit rates based on the particular link conditions.

 

Additional information about AMR file format

File extension .AMR
File category AUDIO
Useful links http://pcsupport.about.com/od/fileextensions/f/amrfile.htm
http://www.amrplayer.com/
File conversion Convert a file to AMR
Developer 3rd Generation Partnership Project (3GPP)
Associated programs Apple iPhone
Audacity
Android
AMR Player
Open Source software
QuickTime
Real Player
VLS Media Player