WMA to CVSD Converter

Produce filtered CVSD delta modulation from WMA

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Military Voice Codec

CVSD is the standard for military voice — convert Windows WMA for specialized systems.

Secure Processing

WMA uploads are deleted after conversion and CVSD results purged within 24 hours.

Online Encoding

No military codec tools needed — convert WMA to CVSD in your browser.

How to convert WMA to CVSD

1

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

2

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

3

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

About formats

WMA (Windows Media Audio) is a family of proprietary audio codecs developed by Microsoft and first released in 1999 as part of the Windows Media framework. Created to compete with MP3 and AAC, WMA Standard uses perceptual coding to deliver what Microsoft claimed was near-CD quality at bitrates as low as 64 kbps — roughly half the data rate MP3 typically needed for comparable results. The codec family grew to include WMA Professional for surround sound and high-resolution audio, WMA Lossless for bit-perfect archival compression, and WMA Voice optimized for spoken content at very low bitrates. Deep integration with Windows, Windows Media Player, and the Zune ecosystem gave WMA a strong distribution advantage throughout the 2000s, and digital rights management (DRM) support made it attractive to online music stores of that era. Encoding and decoding are handled natively by Windows, requiring no third-party software for playback on any Windows machine. Cross-platform support has improved through libraries like FFmpeg and GStreamer, though WMA remains less universally compatible than MP3 or AAC on non-Microsoft devices. The format still appears in legacy media libraries, though newer codecs have largely taken its place for streaming and portable use.
Initial release: 1999
CVSD (Continuously Variable Slope Delta modulation) is a voice digitization method standardized for military and telephony use by NATO and the CCITT during the 1970s. It encodes differences between consecutive samples as a single bit — 1 if the current sample exceeds the prediction, 0 otherwise — while a syllabic companding filter adjusts step size by monitoring runs of identical bits. Operating at 16 to 64 kbps, CVSD balances voice intelligibility against bandwidth, making it the encoding of choice for secure military links and tactical radio systems. The bitstream can be decoded with straightforward hardware, originally built into dedicated integrated circuits. One advantage is implementation simplicity — encoders and decoders need minimal resources, enabling real-time processing on low-power embedded hardware. Robustness under noisy conditions is another strength, as single-bit errors affect only local samples rather than corrupting entire frames. SoX provides software encoding and decoding support, letting modern systems work with legacy CVSD recordings from military archives and vintage telecommunications infrastructure.
Developer: CCITT / NATO
Initial release: 1970

Frequently Asked Questions

Why convert WMA to CVSD?

CVSD adds output smoothing on top of standard CVS delta modulation, improving speech clarity in military radios and telephony. WMA is incompatible with these platforms, making conversion essential.

Which devices and applications use CVSD audio?

Military voice radios, secure telephony terminals, legacy PBX systems, and SoX on desktop platforms all work with CVSD. The format is built for robust speech transmission in noisy channels.

How does CVSD differ from regular CVS?

CVSD applies a low-pass output filter that smooths the reconstructed waveform, resulting in better speech intelligibility than raw CVS. Both use delta modulation but CVSD sounds cleaner.

Is CVSD suitable for anything besides voice?

No — CVSD is engineered solely for speech at low bitrates. Music, sound effects, and ambient recordings lose nearly all fidelity when encoded to this format.

Can I convert a batch of WMA files to CVSD at once?

Yes — upload multiple WMA recordings and Convertio encodes each to CVSD in parallel. Download results individually or as a single combined archive when processing completes.