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How to convert AMR files to MP3


A short article describing how to convert AMR audio files to MP3 with the Pazera Free Audio Extractor. This program is completely free, also for commercial use, and you can download it here.

AMR – Adaptive Multi-Rate (AMR-NB, AMR-WB i AMR-WB+)

AMR is a multimedia container and audio compression format optimized for encoding human speech in order to transmit coded signals in telecommunications networks. AMR compression is widely used in GSM and UMTS systems.

AMR compression is widely used in mobile phones – voice recorders built into these phones very often record audio in AMR format. In addition, the phones that allows to record movies usually store them in a 3GP files, in which the audio stream is mostly encoded using AMR compression.

There are several variants of AMR compression:

  • AMR-NB (Adaptive Multi-Rate – Narrowband) – this is the basic and most commonly used method of AMR compression, which uses audio sampling frequency of 8 kHz, and bitrate 4.75, 5.15, 5.9, 6.7, 7.4, 7.95 , 10.2 or 12.2 kbit/s. Audio files with audio tracks encoded using this method of AMR compression usually have the extension
  • AMR-WB (Adaptive Multi-Rate – Wideband) – a newer version of AMR compression, which uses a 16 kHz of sound sampling and bitrates equal to 6.6, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 or 23.85 kbit/s. The sound quality after AMR-WB compression is generally much better than with the AMR-NB compression. Audio files with audio streams encoded using the AMR-WB compression usually have the extension
  • AMR-WB+ (Extended Adaptive Multi-Rate – Wideband) – the latest variant of AMR compression provides high sound quality, which uses sampling frequency of 16, 24, 32 or 48 kHz, and a bitrates from 5.2 to 48 kbit/s.

AMR files can be played using some software players (eg VLC, MPlayer). Unfortunately, most portable players (except mobile phones) and almost all fixed players do not support AMR format.

AMR to MP3 conversion using Pazera Free Audio Extractor