File Extension AMR

File type: Adaptive Multi-Rate Codec File

About the AMR file type:

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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.

Detailed information for file extension AMR

Category: Audio Files
File format: Proprietary
Open with Windows: Apple QuickTime Player, RealNetworks RealPlayer, Mobile AMR Converter, AMR Tool
Open with Linux: N/A
The common bit rates hosted by the AMR file extension includes 4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, and 12.2Kb per second. These are based on the use of frames containing 160 samples and last for 20 milliseconds. This audio format implements various techniques like DTX (Discontinuous Transmission), CNG (Comfort Noise Generation), and VAD (Voice Activity Detection among others. This file format uses the subtype AMR-WB (Extended version of the Adaptive Multi-Rate for Wideband Speech Codec), AMR-W (AMR for Wideband Speech Codec), and AMR-WB+. The AMR file extension standard was incorporated into the CableLabs PacketCable specification in 2006 after it was accepted as a standard by the European telecommunication organization ETSI. To date, the audio file format is widely supported by the Open-Source community which attributes to the broad range of support available for the standard in the telecommunication industry.