DVMS to CVU Converter

From DVMS to CVU — hassle-free online audio conversion

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Fast Cloud Engine

The heavy lifting happens in the cloud. Your computer stays responsive while DVMS audio converts to CVU on remote servers.

Broader Reach

Moving from DVMS to CVU transitions your audio from an obscure encoding to raw unfiltered delta modulation — a significant practical improvement.

Your Data Stays Private

Your DVMS audio is deleted immediately upon conversion. Any CVU results are purged within 24 hours for your security.

How to convert DVMS to CVU

1

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

2

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

3

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

About formats

DVMS (Dutch Voice Messaging System) is a telephony-grade audio encoding born from the Netherlands' early push toward digital voicemail infrastructure. Deployed through KPN (formerly PTT Telecom) in the mid-1980s, the format stores mono voice data at a narrow 8 kHz sample rate, prioritizing compact message size over sonic breadth. Audio is compressed with a proprietary variant of logarithmic companding similar to European A-law encoding, squeezing recordings to roughly 8 kbit/s while keeping speech intelligible. Each file carries a small header identifying sample rate, compression type, and message metadata, which made automated routing across early PBX and voicemail systems straightforward. Although DVMS never gained traction outside Dutch telecom circles, it influenced how European carriers designed later voice messaging protocols. Tools like SoX and several legacy telephony libraries still read and write DVMS files, allowing archival playback of decades-old messages. Among its practical advantages: extremely small file sizes (a one-minute message occupies roughly 60 KB), reliable speech clarity despite aggressive compression, and a simple container layout that is easy to parse programmatically.
Developer: Dutch PTT Telecom
Initial release: 1984
CVU is an unsigned variant of the CVS telephony audio format, differing in how delta-encoded values are represented in the binary stream. While CVS stores slope delta values as signed quantities, CVU treats them as unsigned, shifting the numerical interpretation of each sample. Both share the underlying CVSD modulation technique — 1-bit adaptive delta coding where step size varies according to recent output bit patterns — operating at comparable rates, typically 16 kbps for narrowband voice at 8 kHz. The signed-versus-unsigned distinction matters at the decoder, where correct interpretation determines proper waveform reconstruction. CVU files appear in telephony and embedded communication contexts where hardware adopted the unsigned convention. A practical advantage is straightforward interfacing with systems using unsigned arithmetic natively, avoiding sign extension in decoders. Like its signed counterpart, CVU achieves extreme bandwidth efficiency, compressing voice into compact bitstreams for constrained links. SoX supports CVU, providing a reliable path for converting these niche telephony recordings into modern formats for analysis or archival.
Developer: CCITT / ITU-T
Initial release: 1970

Frequently Asked Questions

What makes CVU a better choice than DVMS?

Since DVMS has outdated voice mail standard limited to German telephony systems, switching to CVU provides preserves unprocessed telephony signal.

What can I use to play CVU?

You can open CVU with SoX and CVSD-compatible telephony tools.

Will I lose audio quality converting DVMS to CVU?

DVMS stores voice at very low quality. Moving to CVU makes the audio playable everywhere — quality stays consistent with the source.

Can I do this conversion from my phone?

Yes. The online converter is platform-independent — use it from any computer, tablet, or smartphone with a web browser.

Are there limits on DVMS to CVU conversion?

Standard conversions work without restrictions for typical use. Premium plans provide additional speed and capacity for large workloads.

Is registration needed for this conversion?

No account is needed for standard conversions. Simply upload your DVMS recording, choose CVU, and download the result.