MKV → 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. MKV is codec-agnostic: H.264, HEVC, VP9 and AV1 video sit happily beside AAC, FLAC, Opus, DTS or Dolby audio in the same file. 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.

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. AMR destroys music: its 8 kHz bandwidth removes everything above telephone frequencies, and no amount of re-encoding brings it back.

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. MKV has almost no native hardware support — phones, browsers and TVs usually need VLC or a remux before they will play it.

Default bitrate for lossy AMR is 192 kbps, which is transparent for music. You can override to 320 kbps (audiophile) or 96-128 kbps (voice / podcast / smaller file). The bitrate dropdown is exposed in the advanced options before you click convert.

If AMR is lossless (WAV, FLAC), every sample is preserved exactly. If AMR is lossy (MP3, AAC, OGG, Opus), the AMR codec recompresses the source audio — at 192 kbps the result is transparent for almost all content. Going lossy → lossless never recovers detail already discarded.

By default yes — 48 kHz audio in your MKV stays 48 kHz in the AMR output. For CD-burning or legacy player compatibility you can downsample to 44.1 kHz via the sample-rate dropdown; the resampler is high-quality SoX-grade.

Yes — drop a folder of MKV files and we extract audio in parallel. Premium users get more parallel workers; on a 50-file batch this is the difference between a couple of minutes and ten-plus minutes.

If the MKV carries chapter or stream metadata, we copy title / artist / album fields into the AMR container. If not, the AMR comes out untagged — use a tag editor (Mp3tag, Picard) post-export for richer tagging.

Audio demux + encode is fast — typically 5 to 15% of the source duration. A 1-hour MKV → AMR finishes in roughly 3 to 9 minutes on the standard pipeline; Premium parallelism cuts this further for batch jobs.

Not in this tool directly — extract the full audio as AMR, then use /audio-trim/ or /audio-cutter/ to clip the section. The two-step path is usually faster than a combined operation and gives you precise waveform-level control.

Yes — same privacy model as every conversion: isolated workers, no human review, automatic deletion within minutes of completion. The detailed retention window is on /privacy/.