Adaptive Multi-Rate Audio

File Format
Name	Adaptive Multi-Rate Audio
Ontology	Electronic File Formats Audio and Music Adaptive Multi-Rate Audio ; ; ;
Extension(s)	.amr .3ga
MIME Type(s)	audio/amr
LoCFDD	fdd000254
PRONOM	fmt/356
Wikidata ID	Q4676210

Adaptive Multi-Rate Audio is a narrowband audio compression format optimized for speech. AMR is a codec adopted by 3GPP and used by many mobile systems.^[1]^[2]^[3] Apple iOS used the format for voice recordings and voicemail, but changed to the CAF in iOS 12.2^[4]

File Identification

The first 5 bytes of an AMR is the hex values 2321414D52 or ascii #!AMR

Specifications

[https://datatracker.ietf.org/doc/html/rfc4867 RFC 4867 RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB)

Software

Sample Files

References

[0] ttps://en.wikipedia.org/wiki/Adaptive_Multi-Rate_audio_codec

[1] ttp://www.voiceage.com/AMR-NB.AMR.html

[2] ttps://tools.ietf.org/html/rfc4867

[3] ttps://www.macrumors.com/2019/03/13/ios-12-2-improved-audio-message-quality/

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[2]

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Adaptive Multi-Rate Audio

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File Identification

Specifications

Software

Sample Files

References

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