{
 "id": "adaptive-multi-rate-audio",
 "name": "Adaptive Multi-Rate Audio",
 "category": "audio",
 "identifiers": {
  "extensions": [
   "amr",
   "3ga"
  ],
  "mime": [
   "audio/amr"
  ],
  "puid": [
   "fmt/356"
  ],
  "wikidata": [
   "Q4676210"
  ],
  "loc_fdd": [
   "fdd000254"
  ],
  "magic": [
   {
    "offset": 0,
    "hex": "2321414d52",
    "notes": "File Formats Wiki"
   },
   {
    "offset": 0,
    "hex": "2321414d520a",
    "notes": "Adaptive Multi-Rate Audio"
   }
  ],
  "signatures": [
   {
    "name": "Adaptive Multi-Rate Audio",
    "sequences": [
     {
      "position": "bof",
      "offset": 0,
      "pattern": "2321414d520a"
     }
    ]
   }
  ]
 },
 "status": "writable",
 "summary": "The Adaptive Multi-Rate (AMR or AMR-NB or GSM-AMR) audio codec is an audio compression format optimized for speech coding. AMR speech codec consists of a multi-rate narrowband speech codec that encodes narrowband (200–3400 Hz) signals at variable bit rates ranging from 4.75 to 12.2 kbit/s with toll quality speech starting at 7.4 kbit/s.",
 "tools": [
  {
   "name": "FFmpeg",
   "url": "https://ffmpeg.org",
   "license": "LGPL-2.1-or-later / GPL-2.0-or-later",
   "open_source": true,
   "reads": true,
   "writes": true
  },
  {
   "name": "Awave Studio",
   "url": "https://www.fmjsoft.com/awavestudio.html#main",
   "reads": true,
   "writes": true
  },
  {
   "name": "EZ CD Audio Converter",
   "url": "https://www.poikosoft.com/",
   "reads": true,
   "writes": false
  },
  {
   "name": "Media Player (Windows 11)",
   "url": "https://www.wikidata.org/wiki/Q109616196",
   "reads": true,
   "writes": false
  },
  {
   "name": "Parole",
   "url": "http://docs.xfce.org/apps/parole/start",
   "reads": true,
   "writes": false,
   "license": "GNU General Public License",
   "open_source": true
  },
  {
   "name": "PhotoRec",
   "url": "http://www.cgsecurity.org/wiki/PhotoRec",
   "reads": true,
   "writes": false,
   "license": "GNU General Public License",
   "open_source": true
  },
  {
   "name": "Photorecovery",
   "url": "https://lc-tech.com/help/PhotoRecovery/English/index.html",
   "reads": true,
   "writes": false
  },
  {
   "name": "Pinnacle Studio 17 Ultimate",
   "url": "https://www.wikidata.org/wiki/Q123246373",
   "reads": true,
   "writes": false
  },
  {
   "name": "Q1243769",
   "url": "https://support.apple.com/en-gb/guide/quicktime-player/welcome/mac",
   "reads": true,
   "writes": false
  },
  {
   "name": "Q191782",
   "url": "https://www.audacityteam.org/",
   "reads": true,
   "writes": false,
   "license": "GNU General Public License, version 3.0",
   "open_source": true
  },
  {
   "name": "QuickTime X",
   "url": "https://support.apple.com/quicktime",
   "reads": true,
   "writes": false
  },
  {
   "name": "VLC media player",
   "url": "https://www.videolan.org/vlc/",
   "reads": true,
   "writes": false,
   "license": "GNU Lesser General Public License, version 2.1 or later",
   "open_source": true
  }
 ],
 "projects": [
  {
   "name": "File Formats Wiki",
   "url": "http://fileformats.archiveteam.org/wiki/Adaptive_Multi-Rate_Audio",
   "kind": "wiki"
  },
  {
   "name": "PRONOM fmt/356",
   "url": "https://www.nationalarchives.gov.uk/PRONOM/fmt/356",
   "kind": "format-doc"
  },
  {
   "name": "Wikidata Q4676210",
   "url": "https://www.wikidata.org/wiki/Q4676210",
   "kind": "wiki"
  }
 ],
 "provenance": {
  "sources": [
   "converters",
   "ffw",
   "pronom",
   "wikidata"
  ]
 },
 "updated": "2026-10-24",
 "aliases": [
  "AMR-NB",
  "GSM-AMR"
 ],
 "conversions": [
  {
   "to": "flac-free-lossless-audio-codec-1-2-1",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.flac",
   "fidelity": "lossless",
   "losses": "Lossless for decoded audio; a lossy source stays as degraded as it was. WAV may reduce bit depth or drop metadata.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "waveform-audio",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.wav",
   "fidelity": "lossless",
   "losses": "Lossless for decoded audio; a lossy source stays as degraded as it was. WAV may reduce bit depth or drop metadata.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "mpeg-1-2-audio-layer-3",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.mp3",
   "fidelity": "lossy",
   "losses": "Lossy re-encoding.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "ogg",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.ogg",
   "fidelity": "lossy",
   "losses": "Lossy re-encoding.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "mpeg-4-part-14",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.mp4",
   "fidelity": "lossy",
   "losses": "Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "matroska-1-4",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.mkv",
   "fidelity": "lossy",
   "losses": "Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.",
   "url": "https://ffmpeg.org"
  },
  {
   "to": "webm",
   "tool": "FFmpeg",
   "command": "ffmpeg -i in.amr out.webm",
   "fidelity": "lossy",
   "losses": "Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.",
   "url": "https://ffmpeg.org"
  }
 ],
 "structure": [],
 "parsers": [],
 "samples": [],
 "claims": [],
 "verification": []
}