Convert AMR to MP3: Mobile Voice Recording Converter

AMR (Adaptive Multi-Rate) is the voice codec that powered the mobile phone revolution. Standardized by 3GPP for GSM cellular networks, AMR has been the default voice recording format on millions of Nokia, Samsung, Sony Ericsson, and early Android phones. If you have old phone recordings, voicemail archives, or voice memos from pre-smartphone era devices, they are almost certainly in AMR format.

The problem is that AMR was designed exclusively for voice at telephony bandwidths. It operates at bitrates between 4.75 and 12.2 kbps — incredibly efficient for speech but unusable for music and terribly supported outside of phone operating systems. Desktop media players, web browsers, car stereos, and modern streaming services do not play AMR files. Even many modern Android phones have dropped AMR playback support.

Our converter uses dedicated AMR-NB and AMR-WB decoders to read these compact voice files and re-encode them as standard MP3 using a reference-quality MP3 encoder. The result plays everywhere: phones, computers, car stereos, smart speakers, and every media application in existence.

Preservation is the most compelling reason. AMR files from old phones represent irreplaceable audio memories — family voicemails, historic recordings, legal evidence, and personal voice journals. As old devices fail and AMR support dwindles, converting to MP3 ensures these recordings survive in a format that will be playable for decades.

Desktop and modern device playback requires conversion. Windows Media Player does not play AMR. macOS Preview does not play AMR. Most Linux audio players do not play AMR. Even VLC requires specific codec libraries. Converting to MP3 eliminates all playback barriers instantly.

Sharing and archiving demand standard formats. Emailing an AMR file results in an unplayable attachment for most recipients. Cloud storage services cannot preview AMR files. Archival systems expect standard audio formats. MP3 is the safest, most universally understood format for any audio that needs to be shared or preserved long-term.

FFmpeg decodes both AMR-NB (Narrowband, 8 kHz sampling rate, 4.75-12.2 kbps) and AMR-WB (Wideband, 16 kHz, 6.6-23.85 kbps) bitstreams. AMR-NB is far more common in legacy phone recordings, while AMR-WB appears in newer phones and some VoIP systems.

The decoded PCM audio (mono, 8 or 16 kHz) is upsampled to standard MP3 sample rates (22.05 or 44.1 kHz) using a high-quality sinc resampler. The MP3 output uses LAME encoding at 64-128 kbps, which is more than adequate for AMR source quality since the original captures at most 12.2 kbps. Higher MP3 bitrates do not improve quality beyond the source capability but maintain compatibility with players that require minimum bitrates.

Metadata preservation is limited since AMR files rarely contain ID3-style tags. The converter sets basic metadata (filename as title, creation date if available) in the output MP3.