M4V to VOX Converter

Extract M4V audio as Dialogic VOX ADPCM format online

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Apple Video to Telephony

Extract voice from M4V video and encode as VOX ADPCM — the standard for Dialogic-based IVR systems and telephone voice prompts.

Space-Efficient

VOX ADPCM keeps telephony audio files tiny. Convert M4V audio into compact prompts that minimize storage on your phone system.

Any Device Works

Run the M4V to VOX conversion from any computer or mobile device with a browser. No Dialogic tools or Apple software required.

How to convert M4V 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

M4V is a video container format developed by Apple Inc. and introduced alongside the iTunes Video Store in October 2005. Technically, M4V is nearly identical to the standard MP4 format (MPEG-4 Part 14), with the primary distinction being optional FairPlay DRM protection applied to purchased content from the iTunes Store. Unprotected M4V files are fully compatible with any player that handles MP4, as the underlying container structure and codec support are the same. The format typically contains H.264 video and AAC audio, supporting resolutions up to 4K and features like chapter markers, subtitle tracks, and metadata tags for title, artwork, and ratings. Apple chose the M4V extension to distinguish iTunes content from generic MP4 files, primarily so that DRM-protected purchases would be recognized by the Apple ecosystem of devices and software. M4V files play natively on macOS, iOS, iPadOS, and Apple TV, and unprotected versions work seamlessly in most major media players across all platforms. The format gained significant traction as the iTunes Store became a dominant platform for purchasing and renting digital movies and TV shows. Compatibility with the broader MP4 ecosystem means that video and audio streams within DRM-free M4V files can be processed by virtually any modern editing or transcoding tool without conversion.
Developer: Apple Inc.
Initial release: October 2005
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 M4V to VOX?

VOX is the Dialogic ADPCM standard for IVR and telephony. Converting M4V audio creates phone prompts and announcements from Apple video.

How compressed is VOX?

VOX stores 12-bit audio in 4-bit ADPCM, achieving roughly 4:1 compression. Very efficient for telephony prompt storage and delivery.

Is VOX headerless?

Yes — VOX has no file header. The telephony system must know the sample rate (typically 8kHz) when loading and playing VOX files.

Will M4V music convert well?

VOX is speech-oriented. Music from M4V sounds degraded — this format excels at clear voice reproduction for phone system use.

Do DRM M4V files work?

DRM-protected iTunes M4V files cannot be processed. Unprotected M4V videos convert to VOX without any restrictions.