Convert AAC to AMR

Yes, and it is worth planning around. Both formats are lossy, so the AMR encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the AMR from that instead avoids the double pass entirely. AAC is lossy but more efficient than MP3, and it handles up to 48 channels natively rather than being bolted onto a stereo design. AMR is a narrowband speech codec running between 4.75 and 12.2 kbps, modelling the human vocal tract rather than the full audio spectrum.

Not intact. AAC carries a proper metadata block, but AMR has no standard place for artist, album, track number or cover art, so tags are dropped rather than mangled. Keep the AAC as the tagged copy, or re-tag afterwards with a tool like Mp3tag or MusicBrainz Picard. AMR destroys music: its 8 kHz bandwidth removes everything above telephone frequencies, and no amount of re-encoding brings it back.

It is folded down to stereo, because AMR has no practical multichannel mode. The downmix uses the standard coefficients so centre-channel dialogue stays clear and the surrounds are mixed in at reduced level. Anything that depended on discrete channel placement is gone once that happens.

Because one side of it is a speech codec rather than a music codec. It models the human vocal tract and discards everything outside telephone bandwidth, which is fine for a voice memo and destructive for anything with instruments in it. Converting away from it cannot restore the missing frequencies — they were never encoded in the first place. AAC is patent-encumbered, and a handful of very old players still refuse it where they would accept an MP3.

Default is 192 kbps for lossy AMR; pass-through for lossless AMR. Override to 320 kbps for audiophile or 64-96 kbps for spoken-word audiobooks (transparent for voice, halves the file size).

If AAC is lossy and AMR is lossless (e.g. MP3 → WAV), the AMR file is no better than the AAC — you can't recover information that's already been thrown away. If AAC is lossless and AMR is lossy, expect the AMR codec to recompress; at 192 kbps this is transparent for most content.

Yes — title, artist, album, year, track number, album art, and chapter markers (important for audiobooks) are read from AAC and written into the AMR container where the AMR format supports tags. M4B audiobook structure round-trips into M4B and AAX → M4B output.

Yes — drop a folder of AAC files in and we process them in parallel. Premium has more parallel workers and no per-file size cap, so a 500-file batch finishes in minutes rather than tens of minutes.

By default yes (48 kHz AAC → 48 kHz AMR). If you need to downsample for compatibility (e.g. 96 kHz → 44.1 kHz for CD burning) the advanced sample-rate option does this with high-quality resampling.

Yes — the loudness-normalize option applies ITU-R BS.1770 / EBU R128 normalization to the AMR output, targeting -14 LUFS (streaming standard), -16 LUFS (podcast standard), or -23 LUFS (audiobook standard). Useful when batch-converting tracks with varying mastering levels.

MP3 plays universally. AAC plays on Apple, most Android, Sonos. FLAC plays on Sonos and Android, less well on older iPods. M4B audiobooks play with chapter navigation on iOS Books, Audiobookshelf, and Smart Audiobook Player. The advanced options include device presets.