MKV to VOX Converter

Extract MKV audio as Dialogic VOX ADPCM format online

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Video to Phone System

Extract voice audio from MKV and encode as VOX ADPCM — the industry standard for Dialogic IVR platforms and telephony prompts.

Maximum Compression

VOX ADPCM at 4 bits per sample keeps telephony files tiny. Convert lengthy MKV audio into compact phone system prompts.

Secure Processing

MKV uploads are removed after conversion. VOX output files are deleted within 24 hours — your audio content stays private.

How to convert MKV to VOX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose vox or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your vox file right afterwards

About formats

MKV (Matroska Video) is an open-standard multimedia container format developed by the Matroska project, which announced the format in December 2002. Named after the Russian matryoshka nesting dolls, the format is built on the Extensible Binary Meta Language (EBML), a simplified binary variant of XML that provides a flexible and forward-compatible structure. MKV can hold virtually unlimited numbers of video, audio, and subtitle tracks within a single file, supporting codecs from H.264 and HEVC to VP9 and AV1 for video, and AAC, FLAC, Opus, and DTS for audio. A standout feature is comprehensive subtitle support, handling formats from simple SRT text to complex ASS styled subtitles and bitmap-based PGS tracks from Blu-ray discs. MKV also supports chapter markers, attachments (such as fonts needed for styled subtitles), and tagging metadata, making it one of the most feature-rich containers available. The open specification ensures that any developer can implement MKV reading and writing without licensing fees, which has driven widespread adoption across media players, streaming tools, and encoding software. The ability to encapsulate virtually any codec combination in a single, well-organized file has made MKV the preferred container for high-quality video distribution, archival, and personal media libraries.
Developer: Matroska
Initial release: December 6, 2002
VOX is a headerless audio format built around Dialogic ADPCM encoding, widely adopted in telephony, interactive voice response (IVR) systems, and voice mail platforms since the 1980s. Each audio sample is compressed into 4 bits using an algorithm developed by Oki Electric and implemented in hardware on Dialogic Corporation's telephony interface cards. VOX files typically use a sampling rate of 6000 or 8000 Hz, producing extremely compact recordings optimized for speech intelligibility rather than musical fidelity. Because the format carries no header, playback software must know the sample rate and encoding parameters in advance — a trade-off that reduces overhead but demands careful file management. The primary advantage of VOX is storage efficiency: a one-minute voice recording at 8 kHz occupies roughly 240 KB, making it practical for systems storing thousands of prompts. Dialogic ADPCM conforms to the ITU-T G.726 standard, ensuring interoperability across telephony equipment from different vendors. Even as modern call centers migrate to IP-based systems with codecs like Opus, vast libraries of VOX recordings persist in legacy IVR deployments and compliance archives worldwide.
Initial release: 1983

Frequently Asked Questions

Why convert MKV to VOX?

VOX is the Dialogic standard for IVR and telephony audio. MKV video audio can be compressed into phone prompts and voice messages.

How much does VOX compress?

VOX stores 12-bit audio in 4-bit ADPCM — roughly 4:1 compression. Very efficient for storing large numbers of telephony voice prompts.

Does MKV audio quality matter?

VOX is a speech-grade format. Even high-quality MKV audio is downsampled — what matters is clear speech content, not audiophile fidelity.

Is VOX a raw format?

Yes — VOX has no file header. The telephony system receiving the file must know the sample rate and ADPCM encoding parameters.

Can I batch-process MKV files?

Upload multiple MKV videos and convert them all to VOX at once. Efficient for creating telephony prompt libraries from video content.