Convert 3GPP to AMR — Free Online Tool
Convert 3GPP mobile video files to AMR audio, extracting the speech-optimized audio track and re-encoding it using the libopencore_amrnb codec at 12,200 bps — the highest quality AMR Narrowband bitrate. AMR is the native voice format for mobile telephony, making this conversion ideal for extracting voice recordings or call audio from 3GP video files.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
During this conversion, FFmpeg discards the video stream entirely from the 3GPP container and re-encodes the audio track using the AMR Narrowband codec (libopencore_amrnb). The 3GP file's original audio — likely AAC or MP3 — is decoded and transcoded into AMR's highly compressed speech-optimized encoding. AMR Narrowband operates at a fixed 8 kHz sample rate and is constrained to mono audio, so any stereo audio in the source file will be downmixed. The output is a raw .amr file with no container overhead, consisting purely of AMR audio frames at the selected bitrate.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg command-line tool, which handles all decoding, transcoding, and muxing. In the browser version of this tool, FFmpeg runs locally as a WebAssembly binary (FFmpeg.wasm) — no data leaves your device. |
-i input.3gp
|
Specifies the input file in 3GPP format. FFmpeg demuxes the 3GP container to access its video and audio streams; for this conversion, only the audio stream is used. |
-c:a libopencore_amrnb
|
Selects the libopencore_amrnb encoder for the audio output stream. This is an open-source implementation of the AMR Narrowband codec used in GSM mobile telephony, operating at 8 kHz mono — the codec required to produce a valid .amr file. |
-b:a 12200
|
Sets the AMR encoding mode to 12,200 bits per second, which corresponds to AMR-NB Mode 7 — the highest quality and highest bitrate mode available in the AMR Narrowband specification. This mode delivers the best speech intelligibility and is the closest match to standard GSM voice call quality. |
output.amr
|
Defines the output filename and signals FFmpeg to write a raw AMR audio file. The .amr extension triggers the AMR muxer, which writes the IETF AMR file header (#!AMR) followed by AMR-NB encoded audio frames — no video or container metadata is included. |
Common Use Cases
- Extracting voice memos or spoken recordings captured on older feature phones or Android devices that saved video in 3GP format, converting them into AMR for storage or playback on telephony systems
- Converting 3GP video call recordings into AMR audio for submission to voice transcription services that accept telephony-grade audio formats
- Archiving spoken-word content from 3GP clips in AMR format to minimize file size while preserving intelligible speech — AMR at 12,200 bps produces dramatically smaller files than the original AAC audio in the 3GP
- Preparing voice audio from 3GP field recordings for import into IVR (Interactive Voice Response) or VoIP systems that require AMR-encoded audio
- Stripping video from 3GP interview or lecture recordings to produce lightweight AMR audio files compatible with early Nokia or Sony Ericsson mobile handsets
Frequently Asked Questions
Yes, there will be noticeable quality loss because this conversion involves two stages of lossy compression: the original audio in the 3GP (typically AAC) is decoded and then re-encoded into AMR. AMR Narrowband is specifically designed for speech intelligibility at very low bitrates — it operates at 8 kHz sample rate, which means music, ambient sound, or anything other than voice will sound noticeably degraded or muffled. For spoken-word content, however, AMR at 12,200 bps delivers surprisingly clear results.
AMR Narrowband (libopencore_amrnb) is a speech codec standardized for mobile telephony, and the AMR-NB specification hard-limits audio to mono at an 8 kHz sample rate — these are architectural constraints of the codec, not limitations of FFmpeg or this tool. If your 3GP source had stereo AAC audio, FFmpeg automatically downmixes it to mono during the transcode. If you need wider audio bandwidth, AMR Wideband (AMR-WB) operates at 16 kHz and can be selected using the libopencore_amrwb codec instead.
AMR Narrowband defines eight fixed bitrate modes, measured in bits per second: 4750, 5150, 5900, 6700, 7400, 7950, 10200, and 12200. These correspond to AMR mode indices 0 through 7. Lower bitrates produce smaller files but reduce speech clarity, while 12200 bps (the default used by this tool) is the highest quality AMR-NB mode and closely matches the audio quality used in standard GSM phone calls. For archiving or transcription, 12200 is recommended; for maximum compression where intelligibility is the only concern, 4750 or 5150 may suffice.
Significantly smaller, because you are discarding the video stream entirely and encoding only audio at a very low bitrate. A typical 3GP file containing one minute of video with AAC audio might be 2–5 MB; the equivalent AMR audio at 12200 bps would be roughly 90 KB for that same minute. AMR's extremely low bitrates were engineered specifically for storage-constrained mobile devices and narrow-bandwidth voice channels.
Yes. On Linux or macOS, you can use a shell loop: for f in *.3gp; do ffmpeg -i "$f" -c:a libopencore_amrnb -b:a 12200 "${f%.3gp}.amr"; done. On Windows Command Prompt, use: for %f in (*.3gp) do ffmpeg -i "%f" -c:a libopencore_amrnb -b:a 12200 "%~nf.amr". This tool processes one file at a time in the browser, so the FFmpeg command is especially useful if you have a large batch of 3GP files to convert on your local machine.
No. The AMR format is a raw audio bitstream with no container structure capable of storing metadata such as title, artist, date, or geolocation tags. Any metadata embedded in the 3GPP container — including creation timestamps or GPS coordinates sometimes stored by phone cameras — is not carried over to the .amr output. If preserving metadata matters, you would need to use a format like M4A or MP3 as the output instead.
Technical Notes
The libopencore_amrnb encoder used in this conversion is an open-source implementation of the 3GPP AMR-NB speech codec (originally known as GSM-EFR's successor). A critical constraint is that FFmpeg will force the output to 8000 Hz mono regardless of the source 3GP audio's sample rate or channel count — passing -ar 8000 -ac 1 explicitly is redundant since the codec enforces these parameters. The -b:a flag in AMR context does not behave like a true variable bitrate setting; it selects one of the eight discrete AMR mode bitrates, and values that don't exactly match one of the eight defined rates will be rounded to the nearest valid mode. The output .amr file uses the IETF AMR storage format with the magic header "#!AMR\n", which is broadly compatible with mobile playback software. Note that AMR-WB (libopencore_amrwb) offers 16 kHz bandwidth and is supported by the same codec library, but produces .amr files that require AMR-WB-aware players. This tool does not re-encode or alter the video stream — it simply omits it — so no video quality parameters from the 3GP input are relevant to the output.