Convert Matroska Video (.mkv) to Adaptive Multi-Rate Audio (.amr) online for free. Fast, secure video conversion with no watermarks or registration.
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Choose your output settings. The default settings work great for most files.
Click Convert and download your .amr file when it's ready.
AMR (Adaptive Multi-Rate) is a narrowband speech codec designed for GSM cellular networks, operating at extremely low bitrates between 4.75 and 12.2 kbps. Converting MKV to AMR makes sense only when you need voice audio for legacy telecom systems, embedded devices, or applications that specifically require AMR input.
AMR was standardized by 3GPP specifically for encoding human speech over cellular networks, and it remains embedded in VoIP gateways, IVR phone systems, and telecom testing equipment. Some legacy Android voicemail apps and older Nokia handsets store and play recordings exclusively in AMR format, so converting MKV audio to AMR may be required for compatibility with these systems.
The format's extremely low bitrate also makes it useful for scenarios where bandwidth is severely limited. A one-minute AMR file at 12.2 kbps occupies only about 90 KB, compared to roughly 1 MB for MP3 at 128 kbps. For automated phone systems that store thousands of hours of voice prompts or call recordings, AMR's compact size keeps storage costs manageable.
FFmpeg decodes the MKV's audio track and re-encodes it using the libopencore-amrnb encoder. The output is forced to mono at 8 kHz sample rate, which are the only parameters AMR-NB supports. The encoder operates at one of eight fixed bitrates from 4.75 to 12.2 kbps. Any stereo, surround, or high-sample-rate audio in the MKV is downmixed and resampled to fit AMR's constraints.
AMR was designed for intelligible speech, not music. Voice recordings remain clear and understandable at 12.2 kbps, but music, environmental sounds, and complex audio will sound heavily compressed with audible artifacts. The 8 kHz sampling rate means all frequencies above 4 kHz are lost. This is a purpose-built speech codec, and quality expectations should be set accordingly.
| Device | MKV | AMR |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: 1920x1080
Bitrate: 8-12 Mbps
H.264 recommended for fast processing
Resolution: 1080x1080
Bitrate: 3.5 Mbps
Square or 9:16 for Reels
Resolution: 1080x1920
Bitrate: 4 Mbps
9:16 vertical, under 60s ideal
Resolution: 1280x720
Bitrate: 5 Mbps
Under 140s, 512MB max
Resolution: 960x540
Bitrate: 2 Mbps
16MB limit for standard, 64MB for document
Resolution: 1280x720
Bitrate: 4 Mbps
MKV to AMR is a specialized conversion for telecom, embedded systems, and ultra-low-bandwidth scenarios where speech intelligibility matters more than audio fidelity.
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Alle nettlesere, alle enheter
| Egenskap | MKV | AMR |
|---|---|---|
| Fullt navn | Matroska Video | Adaptive Multi-Rate Audio |
| Filendelse | .mkv | .amr |
| Best egnet for | Multiple audio tracks | Speech optimized |