Convert Windows Media Audio (.wma) to Adaptive Multi-Rate Audio (.amr) online for free. Fast, secure audio conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .wma file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .amr file when it's ready.
WMA is Microsoft's audio codec delivering compressed audio typically at 64-320 kbps. AMR (Adaptive Multi-Rate) is a speech-optimized codec created by ETSI for GSM and UMTS mobile voice calls. AMR-NB operates at 8 kHz with bitrates from 4.75 to 12.2 kbps, while AMR-WB extends to 16 kHz at up to 23.85 kbps.
Converting WMA to AMR re-encodes the audio through a speech-optimized codec, dramatically reducing file size while maintaining intelligible voice reproduction. This conversion is specifically designed for speech content — AMR handles music poorly but excels at clear voice at minimal bitrates.
AMR is the native codec for billions of mobile phones and the backbone of GSM voice infrastructure. Telecom voicemail systems, IVR platforms, and MMS gateways often require AMR input. If you have WMA voice recordings from a Windows-based system that need to enter the mobile telephony pipeline, AMR conversion is required.
The extreme compression (128 kbps WMA to 12.2 kbps AMR-NB) makes AMR ideal for mass archival of voice content. Call center recordings, dictation files, and interview archives stored as WMA can be compressed further for long-term storage.
FFmpeg decodes the WMA stream to PCM, resamples to 8 kHz (AMR-NB) or 16 kHz (AMR-WB), downmixes to mono, and encodes using libopencore-amrnb or libopencore-amrwb. The AMR codec uses ACELP (Algebraic Code-Excited Linear Prediction) optimized for the human speech spectrum. Since both WMA and AMR are lossy, the transcode compounds quality loss. The output is written as raw AMR (.amr) or wrapped in a 3GP container.
Double lossy transcoding (WMA to AMR) produces lower quality than converting from an uncompressed source. AMR-NB is narrowband (300-3400 Hz) and sounds like a standard phone call. AMR-WB extends to 50-7000 Hz for HD Voice quality. Neither is suitable for music. For the best results, start from WMA Lossless or the highest available WMA bitrate.
| Device | WMA | AMR |
|---|---|---|
| Windows PC | Native | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Resolution: N/A
Bitrate: 256 kbps
AAC format required
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
WMA to AMR conversion bridges Windows audio with mobile telephony infrastructure. Use AMR-WB for HD Voice quality and reserve AMR-NB for legacy systems requiring narrowband compatibility.
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| No |
| Funktion | WMA | AMR |
|---|---|---|
| Fulde navn | Windows Media Audio | Adaptive Multi-Rate Audio |
| Filendelse | .wma | .amr |
| Bedst til | Windows native | Speech optimized |