MKV to AMR Converter

Extract MKV Audio to AMR: What This Tutorial Covers

This tool throws away the video in a Matroska (.mkv) file and keeps only the soundtrack, re-encoding it as AMR — the speech codec built for mobile telephony. Be clear-eyed before you start: MKV normally carries full-bandwidth audio (AAC, AC-3, DTS, Opus or FLAC), and AMR is the narrowest target on the site. Speech survives it and shrinks enormously; music does not. This walk-through covers the one step that trips everybody up on this page — you have to choose the AMR variant before the bitrate list has anything in it — plus what happens to an MKV's extra audio and subtitle tracks along the way.

How to Convert MKV to AMR

1. Upload Your MKV File: Drag the .mkv onto the page or click "+ Add Files" to pick it from your computer. Several files can be queued and converted with the same settings.
2. Pick AMR Narrow Band or AMR Wide Band: Open Advanced Options and choose one under Audio Codec. Neither is preselected, and this choice controls everything below it — the bitrate list, the sample rate, and whether the file is telephone-grade or HD Voice-grade.
3. Set File Compression, Then Trim if Needed: Under File Compression, either leave Quality Preset (its Preset list opens on Highest) or switch to Constant Bitrate and pick an exact 3GPP mode. Trim is set to Unchanged; open it to enter a Start time and Duration and export only part of a long recording.
4. Convert and Download: Click Convert and download the .amr. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically a few hours later — no sign-up, no watermark.

Walk-through: Why the Bitrate List Starts Out Empty

The Constant Bitrate dropdown on this page is populated by whichever AMR variant is active, and nothing is selected when the page loads. That is not a stuck control — it is waiting on step 2. Choose an Audio Codec first and the list fills in immediately:

• Choose AMR Narrow Band and the list becomes the eight 3GPP narrowband modes: 4.75, 5.15, 5.90, 6.70, 7.40 (often labelled toll quality), 7.95, 10.2 and 12.2 KBPS. Audio Sample Rate simultaneously locks to 8000 HZ, because narrowband AMR has no other legal rate.
• Choose AMR Wide Band and you get the nine wideband modes instead: 6.60, 8.85, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85 KBPS, with Audio Sample Rate locked to 16000 HZ.
• Leave File Compression on Quality Preset if you do not care about hitting an exact mode — the preset is mapped onto the codec's bitrate range for you, and the encoder snaps the result to the nearest legal AMR mode.
• Ignore Audio Channel. MONO is the only entry the dropdown offers, for both variants, because AMR is a single-channel codec by design.

AMR Narrow Band vs AMR Wide Band

What Survives the Trip from MKV to AMR

Matroska is deliberately a multi-track envelope — the format's own documentation describes it as holding "many audio, video and subtitles streams" with selectable tracks and chapter entries, and it is now standardised as RFC 9559 (October 2024). A .amr file is the opposite: one mono speech stream and nothing else. Everything below is dropped, not hidden:

Common Errors and How to Fix Them

• "The bitrate dropdown is blank" — Pick AMR Narrow Band or AMR Wide Band under Audio Codec first. The modes are variant-specific, so the list has nothing to show until one is selected.
• "The output sounds thin, muffled or warbly" — That is AMR behaving normally. Narrowband keeps only the telephone band and even wideband stops near 7 kHz, so cymbals, bass and room tone disappear. For anything you intend to actually listen to, use MKV to MP3 instead.
• "My player won't open the .amr" — Desktop players are patchy with AMR, and some that read narrowband files reject wideband ones because the header differs. VLC opens both; otherwise convert onward with AMR to MP3.
• "The wrong language track was converted" — There is no track picker here, so a multi-language MKV converts whichever audio stream the container marks as default. Remux the MKV with the track you want set as default, then convert.
• "The result is mono but my source was stereo" — Expected. AMR is a one-channel codec; MONO is the only Audio Channel value offered.
• "The file is far bigger than I wanted" — AMR bitrates are tiny, so size is nearly all duration. Trim on this page, or cut the source first with the Video Cutter.

When This Doesn't Work

AMR is the wrong destination whenever fidelity matters — songs, film soundtracks, podcasts, anything musical. No mode setting rescues that; the bandwidth is gone by design. Encrypted or partially downloaded MKV files may also fail to decode at all, and an MKV whose audio stream is itself broken produces a silent result no matter what you pick. The honest default for most people extracting sound from a Matroska file is MKV to MP3 for listening or MKV to WAV for editing; reach for AMR only when a feature phone, voicemail platform, IVR menu, or telephony system specifically demands a .amr file.

Frequently Asked Questions

Why is the Constant Bitrate list empty when the page loads?

Because the AMR bitrate modes are defined per variant and no variant is preselected. AMR Narrow Band and AMR Wide Band have completely different mode tables — eight rates versus nine, at different sample rates — so the dropdown has nothing valid to offer until you choose one under Audio Codec. Pick a variant and the modes appear at once. If you would rather not think about modes, leave File Compression on Quality Preset; that path derives a bitrate from the codec's own range for you.

What is the difference between AMR Narrow Band and AMR Wide Band?

Narrowband (AMR-NB) samples at 8 kHz and reproduces roughly the 300–3,400 Hz telephone band across eight modes from 4.75 to 12.2 KBPS. Wideband (AMR-WB) samples at 16 kHz, covers roughly 50–7,000 Hz across nine modes from 6.60 to 23.85 KBPS, and is the codec behind "HD Voice" — it is also published by the ITU as Recommendation G.722.2, "Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB)". Wideband sounds clearly better on voice; narrowband is what the oldest handsets and telephony equipment expect.

How can I tell whether an AMR file is narrowband or wideband?

By its first bytes — AMR files declare their variant in a plain ASCII magic string at the start of the file. We checked encoder output both ways: a narrowband file begins #!AMR and a wideband file begins #!AMR-WB, even though both use the .amr extension. That is also why a player that only understands classic narrowband AMR can silently refuse a wideband file you made on this page; if a device rejects your output, re-run it as Narrow Band before assuming the conversion failed.

Will music or a film soundtrack survive conversion to AMR?

No, and no setting changes that. AMR is a speech codec: it models a human vocal tract rather than storing a general waveform, and it discards everything outside the voice band before it even reaches the bitrate you chose. Instruments lose their harmonics, bass vanishes, and cymbals turn to hiss. Spoken content — interviews, narration, lecture recordings, dialogue — stays perfectly intelligible, which is exactly what AMR was designed for. For music extracted from an MKV, use MKV to MP3 or MKV to FLAC.

My MKV has several audio tracks — which one is converted?

The one the container marks as the default audio track. This page has no track selector, so a film with an English track plus commentary and dub languages produces a single .amr from whichever stream is flagged default, and the rest are dropped. If that is not the track you need, remux the MKV first with your preferred stream set as default. The same applies to soft subtitles and chapters: AMR has no way to store them, so they simply do not carry over.

How large is an AMR file per minute of speech?

Small enough that duration, not quality, drives the number. At the 12.2 KBPS narrowband maximum, a minute of audio is about 90 KB; at 4.75 KBPS it is closer to 35 KB; at the 23.85 KBPS wideband maximum roughly 175 KB. Those figures follow directly from the bitrate, because AMR modes are constant-rate. An hour of narrowband speech therefore lands around 5 MB — which is exactly why voicemail systems and messaging platforms standardised on it.

Can I convert only part of a long MKV?

Yes. Open Trim in Advanced Options — it starts on Unchanged — and enter a Start time and a Duration, either in seconds or as HH:MM:SS.sss. Only that span is decoded and encoded, which is much faster than converting a two-hour file and cutting it afterwards. If you would rather cut the video first and keep a video copy of the excerpt, use the Video Cutter and convert the result.

Does any of the MKV's video end up in the output?

None. AMR is an audio-only file format with no video capability whatsoever, so the picture is decoded only far enough to reach the audio stream and is then discarded. What you get back is a single mono speech file. If you actually wanted a smaller video rather than an audio extract, convert to MKV to MP4 or compress the original with Compress MKV instead.

What happens to my file after the conversion?

Your MKV is uploaded over an encrypted connection, converted on our servers, and both the upload and the resulting .amr are deleted automatically a few hours afterwards. Nothing is shared or made public, there is no sign-up, and no watermark or audio tag is added to the output. The original file on your own device is never modified — the AMR is written as a new file.