AMR (Adaptive Multi-Rate) is an audio compression format optimized for speech coding. It is commonly used in mobile phones for voice recordings and audio playback.
Common Uses
Voice recordings
Mobile audio
Telephony
AMR Conversion FAQ
What is an AMR audio file?
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AMR is a narrow-band speech codec originally used by 2G/3G mobile networks. AMR captures intelligible voice at very low bitrates and is common in voicemail exports, push-to-talk recordings, and older feature-phone voice memos. AMR makes voice recordings absurdly small — an hour of speech fits in a few megabytes — and it is what many phones still record calls in.
How much quality has already been lost in an AMR file?
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Whatever the original encoder decided to discard, and it cannot be recovered. AMR compresses by modelling what the ear will not notice — quiet sounds sitting under loud ones, frequencies at the edges of hearing — and permanently removing it. At a healthy bitrate that is inaudible to almost everyone. What it is not is reversible, so converting to a lossless format preserves the current state rather than restoring the original. AMR is a narrowband speech codec running between 4.75 and 12.2 kbps, modelling the human vocal tract rather than the full audio spectrum.
Why does my AMR recording sound thin compared to music?
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Because it was never meant to carry music. AMR is a narrowband speech codec built for mobile networks, tuned to keep words intelligible at a bitrate measured in single-digit kilobits. Everything outside the range of the human voice is discarded at capture time. Converting to a full-range format keeps the recording usable everywhere, but it cannot add back frequencies that were never sampled. AMR destroys music: its 8 kHz bandwidth removes everything above telephone frequencies, and no amount of re-encoding brings it back.
Where do AMR files usually come from?
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Voicemail systems, push-to-talk radios, older handsets and telephony recording — anywhere audio had to travel over a narrow, expensive channel. That heritage explains both why the files are tiny and why they sound the way they do. Converting makes them play in ordinary software; it does not, and cannot, add fidelity the capture never had. AMR is Adaptive Multi-Rate, the speech codec 3GPP standardised for GSM voice calls and mobile voice recorders.
Why does my AMR file show up with no track name or artwork?
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Because the format has essentially nowhere to store them. AMR was specified around the audio itself, with no standard place for a title, an album or a cover image, so players fall back to displaying the filename. Converting to a tagged format is what makes a library browsable — the tags are written during conversion rather than recovered, so expect to fill in anything the source never carried.
Should I still be saving new files as AMR?
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Only if something downstream demands it. The format still opens, and there is no urgency about converting an archive that is not causing trouble, but it is no longer where the tooling or the efficiency is going. For anything new, a current format costs nothing extra and avoids the next round of this question a few years from now.
Why will an AMR file not play in my browser?
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Browsers decode a short, fixed list of audio formats and AMR is outside it, so the file downloads instead of playing or the player simply reports an error. Desktop software with a wider codec set opens it without trouble. If the audio has to play on a web page, converting it is the fix — no player configuration will add a decoder the browser does not ship.
What bitrate should I convert my AMR files to?
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Match the destination, not the source. For music, 256 to 320 kbps is transparent to nearly every listener; for speech and podcasts, 96 to 128 kbps is plenty and halves the file again. Encoding above the source bitrate is wasted space — it faithfully preserves audio that has already been through a lossy pass and recovers nothing the first encoder discarded.
Is AMR lossy or lossless?
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AMR is lossy — the encoder removes data the encoder judges to be inaudible to reach a small file size.
What should I convert AMR to for sharing?
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For email and social-media sharing, convert AMR to MP3 — universal playback and small file size. For high-fidelity sharing with audiophiles, convert to FLAC or WAV to preserve the original quality.
