.amr File Extension
.amr file contains, which apps open AMR speech recordings, how Poly supports them, and when to convert them. File extension details for .amr
Partial Support| File type | Adaptive Multi-Rate narrowband speech audio |
|---|---|
| MIME type | |
| Encoding | Binary AMR-NB speech frames after an ASCII storage header |
| Operating systems | Windows, macOS, Linux, Android |
| Opens with | VLC media player, FFmpeg, Android media apps |
| Poly support | Partial. Poly recognizes and stores .amr speech recordings. |
| Indexed by Poly | Partial. Poly indexes filenames and basic file properties, but not speech or audio similarity. |
| Preview in Poly | Limited. Files open in the audio player, but most browsers cannot decode AMR. |
| Poly agent | Partial. The Poly agent can find and manage the file by name and properties. |
What kind of file is an .amr?
An .amr file is usually a speech recording encoded with Adaptive Multi-Rate narrowband, or AMR-NB. It uses the audio/amr MIME type. AMR was designed for cellular voice rather than music: it samples at 8 kHz, processes 20-millisecond frames, and offers eight modes from 4.75 to 12.2 kbit/s.1
A standard single-channel file starts with the six bytes 23 21 41 4D 52 0A, which spell #!AMR followed by a newline. AMR-WB instead starts with #!AMR-WB\n, while multichannel storage starts with #!AMR_MC1.0\n.1 Check the complete header because the shared #!AMR prefix is not enough to distinguish them.
recording.3gp to recording.amr does not remove its 3GP container. Renaming an MP3 or WAV file to .amr does not encode it as AMR.How do I open an .amr on my computer?
VLC and FFmpeg can open AMR files on Windows, macOS, and Linux. FFmpeg can also inspect or convert the recording.23 Android supports AMR-NB decoding in standalone AMR and 3GP files, so compatible Android media apps can play them.4
Web playback is unreliable. If a browser refuses an .amr attachment, download it and use a maintained local player. Do not simply change the suffix to .mp3; proper conversion must decode and re-encode the audio.
Poly support for .amr
Poly recognizes .amr files, stores and syncs them, and makes their names and basic properties searchable. They open in Poly's audio player, but playback depends on browser AMR support, which is generally unavailable.
Poly does not currently extract an AMR transcript, create audio-similarity indexing, or make the recording's spoken content available to the Poly agent. Convert a working copy to a supported audio format before upload when you need playback, transcription, content search, or agent understanding. Keep the original when provenance matters.
History of .amr
ETSI developed AMR for GSM cellular systems, and 3GPP selected it as the mandatory narrowband speech codec for third-generation cellular systems.1 Its multiple modes let a network balance speech bitrate against error protection as radio conditions changed.
The IETF's RFC 4867 standardized both RTP carriage and a standalone storage format in 2007. The compact .amr convention became useful for voice messages, mobile recordings, and telephony archives, but its 8 kHz sampling remains a poor choice for music or high-fidelity production.
Working with .amr and alternatives
| Need | Practical choice | Tradeoff |
|---|---|---|
| Edit or preserve decoded samples | WAV or FLAC | Much larger, and cannot restore detail AMR discarded |
| Compact modern speech delivery | Opus | Transcoding adds another lossy generation |
| Broad consumer compatibility | MP3 or AAC | Convenient, but another lossy encode can add artifacts |
| Keep an authentic source record | Original .amr | Limited browser and app compatibility |
Decode to WAV or FLAC before editing when practical. Use Opus, AAC, or MP3 only when file size or target-player compatibility matters more than avoiding another lossy generation. No conversion can recreate frequencies or detail already removed by AMR-NB.
Footnotes
- Internet Engineering Task Force. RFC 4867: RTP Payload Format and File Storage Format for the AMR and AMR-WB Audio Codecs. ↩ ↩2 ↩3
- VideoLAN. VLC Features. ↩
- FFmpeg. Supported File Formats. ↩
- Android Developers. Supported Media Formats. ↩