Convert 3GP to AMR — Free Online Converter

Both 3GP and AMR originate from the same GSM mobile ecosystem. The 3GP container wraps video and audio streams together, while the AMR (Adaptive Multi-Rate) format is a standalone audio file containing only the voice-optimized codec operating at 8 kHz with bitrates from 4.75 to 12.2 kbps. Converting 3GP to AMR strips the video track and extracts the AMR audio stream, often as a direct copy without re-encoding, producing the smallest possible voice file.

AMR files are still used in telephony systems, voicemail servers, IVR (Interactive Voice Response) platforms, and embedded devices where bandwidth is extremely limited. A standalone AMR file is far smaller than the 3GP wrapper — removing the video track and container overhead can cut file size by 80-95%. This conversion is also useful when feeding audio to speech recognition systems optimized for AMR input, or when sending audio via MMS on networks that enforce strict size limits.

When the 3GP file already contains AMR-NB audio, FFmpeg performs a direct stream copy — the AMR frames are extracted without decoding and rewritten into a standalone .amr file with the proper #!AMR\n header. This is nearly instantaneous and completely lossless. If the 3GP contains AAC audio instead, FFmpeg decodes to PCM then re-encodes using libopencore-amrnb at 8 kHz mono, targeting the specified AMR bitrate mode (MR475 through MR122).