Convert RAW Audio to AMR — Free Online Converter
Convert Raw PCM Audio (.raw-audio) to Adaptive Multi-Rate Audio (.amr) online for free. Fast, secure audio conversion with no watermarks or registrati...
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How to Convert
Upload your .raw 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.
About RAW Audio to AMR Conversion
Raw PCM audio represents the most fundamental form of digitized sound: an unbroken sequence of binary sample values with absolutely no container, header, or metadata. To correctly interpret the data, you must externally specify the sample rate, bit depth, byte ordering, and number of channels. Raw audio files are generated by embedded voice recording hardware, telephone system DSP boards, industrial intercom systems, and scientific data loggers that prioritize simplicity over self-description.
AMR (Adaptive Multi-Rate) is a speech codec developed by the European Telecommunications Standards Institute (ETSI) for GSM and 3G mobile telephony. Operating at bitrates from 4.75 to 12.2 kbps with an 8 kHz sample rate, AMR is optimized exclusively for human voice — it achieves extraordinary compression ratios for speech while completely discarding frequency content outside the 300-3400 Hz band.
Why Convert RAW Audio to AMR?
Raw PCM files are impractical for voice distribution — a one-minute mono recording at 8 kHz / 16-bit is nearly 1 MB of headerless data that no phone can play. AMR compresses that same minute of speech to approximately 15-60 KB depending on the chosen bitrate mode, a reduction of 17x to 67x. This makes AMR ideal for voice memo sharing over MMS, email attachments, and limited-bandwidth networks.
Beyond compression, AMR solves the metadata problem inherent to raw audio. The AMR file header and frame structure make the audio self-describing and playable on billions of GSM phones without any parameter specification. For embedded systems that capture raw voice data, AMR conversion creates the smallest possible distributable voice files.
Common Use Cases
- Compressing raw voice recordings from embedded intercom systems for MMS delivery to mobile phones
- Converting raw telephony DSP captures into AMR for compatibility with cellular voice mail systems
- Creating ultra-compact voice memos from raw microcontroller audio for transfer via Bluetooth on feature phones
- Packaging raw voice recordings from industrial equipment for automated phone notification systems
- Reducing storage footprint of raw voice logs from call center recording hardware
How It Works
FFmpeg reads the raw PCM input with mandatory format flags: `-f s16le -ar 8000 -ac 1` for 16-bit signed little-endian mono at 8 kHz (the native AMR sampling rate). If the raw source uses a different sample rate, FFmpeg resamples to 8000 Hz automatically. Multichannel raw audio is downmixed to mono. The encoder uses libopencore-amrnb to produce AMR-NB frames at a selectable bitrate mode (4.75, 5.15, 5.90, 6.70, 7.40, 7.95, 10.2, or 12.2 kbps). Output includes the standard AMR file header (`#!AMR\n`).
Quality & Performance
AMR is a speech-only codec — it discards all frequency content outside the 300-3400 Hz telephone band. Music, environmental sounds, and high-frequency detail are severely attenuated or eliminated. At 12.2 kbps (the highest mode), speech quality is comparable to a clear phone call. At 4.75 kbps, speech remains intelligible but sounds noticeably degraded. Since raw PCM provides perfect uncompressed input, the AMR encoder operates at its theoretical best quality for the chosen bitrate.
Device Compatibility
| Device | RAW Audio | AMR |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No | No |
Recommended Settings by Platform
Spotify
Resolution: N/A
Bitrate: 320 kbps
OGG Vorbis preferred
Apple Music
Resolution: N/A
Bitrate: 256 kbps
AAC format required
SoundCloud
Resolution: N/A
Bitrate: 128 kbps
Lossless FLAC/WAV for best quality
Podcast
Resolution: N/A
Bitrate: 128 kbps
MP3 mono for spoken word
Tips for Best Results
- 1If your raw audio is already at 8 kHz mono, specify those exact parameters to avoid unnecessary resampling artifacts
- 2Use the 12.2 kbps mode for maximum speech clarity — lower modes should only be used when extreme file size reduction is critical
- 3For wideband speech quality, consider AMR-WB (.awb) which uses 16 kHz sampling for noticeably clearer voice reproduction
- 4Always verify the raw file's actual sample rate — specifying 44100 Hz when the source is actually 8000 Hz will produce chipmunk-speed audio
- 5AMR is unsuitable for music or environmental audio — use AAC, OGG, or FLAC for any non-speech content
Raw audio to AMR conversion transforms headerless binary samples into the most compact speech format available, providing extreme compression and universal mobile phone compatibility for voice content.