Convert Advanced Systems Format (.asf) to Adaptive Multi-Rate Audio (.amr) online for free. Fast, secure video conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .asf 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.
AMR (Adaptive Multi-Rate) is a speech-optimized audio codec standardized by 3GPP, operating at a fixed 8 kHz sample rate with bitrates from 4.75 to 12.2 kbps. ASF files often contain WMA audio recorded at much higher quality. Converting ASF to AMR aggressively compresses the audio down to telephony-grade quality, producing extremely small files suitable for voice messaging and low-bandwidth transmission.
AMR was designed specifically for human speech on cellular networks. When you need to extract a voice recording from an ASF file and share it via MMS or a voice messaging system that requires AMR, this conversion is necessary. AMR files are tiny — a one-minute voice clip can be under 100 KB — making them ideal for environments with extreme bandwidth or storage limitations.
The converter decodes the WMA audio from the ASF container, resamples it to 8 kHz mono, and encodes it with the AMR-NB (Narrowband) codec. The output uses the standard AMR file format with a '#!AMR\n' magic header. The codec dynamically selects from 8 bitrate modes (4.75-12.2 kbps) per 20 ms frame based on content complexity, allocating more bits to voiced segments and fewer to silence.
AMR is designed for intelligible speech, not music. Audio quality is comparable to a telephone call — voices are clear but all frequencies above 3.4 kHz are discarded. Music, environmental sounds, and multiple overlapping speakers will sound noticeably degraded. This is a deliberate trade-off for extreme compression.
| Device | ASF | 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
ASF to AMR is a specialized conversion for voice-only content destined for cellular voice messaging, telephony systems, or devices that require the 3GPP AMR format.
Ασφαλής μεταφορά
Κρυπτογραφημένες μεταφορτώσεις HTTPS
Απόρρητο πρώτα
Τα αρχεία διαγράφονται αυτόματα μετά την επεξεργασία
Χωρίς εγγραφή
Ξεκινήστε τη μετατροπή αμέσως
Λειτουργεί παντού
| No |
8MB free, 50MB Nitro
Οποιοδήποτε πρόγραμμα περιήγησης, οποιαδήποτε συσκευή
| Χαρακτηριστικό | ASF | AMR |
|---|---|---|
| Πλήρες όνομα | Advanced Systems Format | Adaptive Multi-Rate Audio |
| Επέκταση | .asf | .amr |
| Ιδανικό για | Streaming optimized | Speech optimized |