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Convert MKV to AMR - Extract Speech Audio for Mobile

Extract voice audio from MKV videos. Get mobile-optimized AMR files instantly.

Step 1: Upload your files

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Step 2: Choose format
Step 3: Convert files

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Need Speech Audio From Your Video?

You have an MKV video file containing a lecture, interview, or voice recording, and you need just the audio in a format optimized for mobile phones. AMR is the answer-it's the standard audio codec used by mobile networks worldwide for voice transmission.

Converting MKV files to AMR extracts the speech content while creating extremely small files. In our testing, a 10-minute voice recording converts to under 1MB in AMR format, making it perfect for sharing via MMS or storing voice notes on devices with limited storage.

How to Convert MKV to AMR

  1. Upload your MKV file - Drag and drop or click to select your video
  2. Choose AMR as output - The converter will extract the audio track
  3. Download your AMR file - Ready for mobile playback and sharing

The entire process happens in your browser. No software installation required, and your files stay private on your device.

MKV vs AMR: Understanding the Conversion

MKV (Matroska Video) is a flexible container format that can hold video, audio, and subtitles in a single file. When you convert to AMR, we extract only the audio stream and re-encode it using the Adaptive Multi-Rate codec.

MKV Characteristics

  • Container format supporting multiple audio/video codecs
  • Often contains high-quality audio tracks (AAC, FLAC, AC3)
  • File sizes range from megabytes to gigabytes
  • Requires specific players or codec packs on some devices

AMR Characteristics

  • Speech-optimized audio codec adopted by 3GPP in 1999
  • Extremely small files - bitrates from 4.75 to 12.2 kbps (narrowband)
  • Sample rate of 8 kHz for AMR-NB, 16 kHz for AMR-WB
  • Native support on virtually all mobile phones

In our testing, AMR files are typically 90-95% smaller than the original MKV audio track. This comes with a trade-off: AMR is optimized for voice, not music. Speech sounds clear, but musical content will lose fidelity.

When to Use MKV to AMR Conversion

Extracting Lectures and Presentations

Recorded a lecture or conference presentation in MKV format? Convert to AMR to create a compact audio version you can listen to on your commute. The speech remains clear while the file size drops dramatically.

Voice Messages and Memos

Many messaging apps and mobile systems use AMR for voice recordings. If you have speech content in an MKV video that you want to share as a voice message, AMR is the native format these systems expect.

Archiving Interview Audio

Video interviews take up significant storage space. Extracting the audio to AMR preserves the spoken content in a fraction of the size-useful for archives where you only need to reference what was said, not how it looked.

Mobile Phone Ringtones and Alerts

Some older or basic mobile phones specifically require AMR format for custom ringtones and notification sounds. Extract a voice clip from your MKV video and use it directly.

AMR Format Variants: NB vs WB

AMR comes in two main variants, and understanding the difference helps you get better results:

AMR-NB (Narrowband)

  • Frequency range: 200-3400 Hz
  • Bitrates: 4.75 to 12.2 kbps
  • Sample rate: 8 kHz
  • Best for: Basic voice, maximum compatibility, smallest files

AMR-WB (Wideband)

  • Frequency range: 50-7000 Hz
  • Bitrates: 6.6 to 23.85 kbps
  • Sample rate: 16 kHz
  • Best for: Higher quality voice, modern devices

Our converter uses settings optimized for clear speech reproduction while maintaining broad device compatibility.

Technical Features of AMR

AMR uses several advanced technologies that make it ideal for speech:

  • ACELP encoding - Algebraic Code-Excited Linear Prediction optimizes for human voice patterns
  • Voice Activity Detection (VAD) - Detects when speech is present vs silence
  • Discontinuous Transmission (DTX) - Reduces data during silent periods
  • Comfort Noise Generation (CNG) - Fills silence with natural background noise instead of jarring gaps

These features mean your converted speech audio sounds natural and plays smoothly, even at very low bitrates. In our testing, speech remains intelligible even at the lowest 4.75 kbps setting, though we recommend higher bitrates for content you plan to share.

Alternative Formats to Consider

AMR excels for speech on mobile devices, but it may not be ideal for every situation:

  • MKV to MP3 - Better for music or when you need universal compatibility across all devices and platforms
  • MKV to AAC - Higher quality audio, good balance of size and fidelity for both speech and music
  • MKV to WAV - Uncompressed audio for editing or archival, much larger files
  • MKV to M4A - Apple-friendly format with good quality

Choose AMR specifically when you need the smallest possible files for speech content, or when targeting mobile phones that require AMR format.

Device and Browser Compatibility

Our MKV to AMR converter works entirely in your web browser:

  • Operating Systems: Windows, macOS, Linux, ChromeOS
  • Browsers: Chrome, Firefox, Safari, Edge, Opera
  • Mobile: iOS Safari, Android Chrome

The converted AMR files play on virtually all mobile phones, including older feature phones. For desktop playback, VLC media player, QuickTime, and RealPlayer all support AMR.

Pro Tip

For the clearest speech in AMR format, ensure your source MKV has clean audio without heavy background music. AMR handles voice well but struggles when speech competes with other sounds. If possible, use content where speech is the dominant audio.

Common Mistake

Expecting music to sound good in AMR. This format is engineered for speech frequencies only (200-3400 Hz for narrowband). Music, sound effects, and ambient audio will sound muddy or distorted. Use MP3 or AAC for music content.

Best For

Extracting lectures, interviews, voice memos, or spoken content from MKV videos when you need extremely small files for mobile devices or messaging systems that use AMR natively.

Not Recommended

Don't use AMR for music extraction, podcast production where quality matters, or any content where audio fidelity is important. The extreme compression sacrifices everything except basic speech intelligibility.

Frequently Asked Questions

AMR (Adaptive Multi-Rate) is an audio format optimized for speech. It was adopted as the standard voice codec for mobile networks (GSM and 3G) in 1999. AMR files are extremely small because they're designed specifically for voice, not music.

For speech content, the quality remains clear and intelligible. AMR is designed for voice frequencies (200-3400 Hz for narrowband). However, music and complex audio will lose significant quality because AMR discards frequencies outside the speech range.

Dramatically smaller. AMR uses bitrates from 4.75 to 12.2 kbps for narrowband, compared to audio in MKV files which often uses 128-320 kbps. A 10-minute recording might be 100MB as MKV video but under 1MB as AMR audio.

Yes. VLC media player (free, available for Windows/Mac/Linux) plays AMR files natively. QuickTime on Mac and RealPlayer also support AMR. Some versions of Windows Media Player may require an additional codec.

AMR-NB (narrowband) uses 8 kHz sample rate and captures frequencies up to 3400 Hz. AMR-WB (wideband) uses 16 kHz sample rate and captures up to 7000 Hz, providing noticeably clearer speech at the cost of slightly larger files.

Choose AMR when you need the smallest possible file size for speech content, when targeting mobile phones that require AMR format, or when creating voice messages for MMS. Choose MP3 when you need universal compatibility or are working with music.

The converter extracts the primary audio track from your MKV file. If your MKV contains multiple audio tracks (like different languages), it will use the default track. The video content is discarded, leaving only the audio in AMR format.

Yes, AMR is specifically designed for voice recordings. It's the format many phones use internally for voice memos and voice messages because it produces very small files while keeping speech clear and understandable.

Yes, many mobile phones accept AMR for custom ringtones, especially older or basic phones. Extract a voice clip from your MKV video and the resulting AMR file can often be used directly as a ringtone.

Conversion is fast because AMR files are small and the encoding is efficient. A typical 10-minute video converts in seconds. Longer videos or slower internet connections may take proportionally longer for upload.

Conversion happens in your browser using client-side processing. Your files are not uploaded to external servers, keeping your content private. This also means conversion works offline once the page has loaded.

Our converter handles MKV files with any common audio codec including AAC, MP3, AC3, DTS, FLAC, Vorbis, and Opus. The audio is decoded and re-encoded to AMR regardless of the original codec.

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