AVR to CVSD Converter

Transform Audio Visual Research AVR into CVSD modulation

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Research Audio Rescue

Extract audio from the legacy AVR format and convert to CVSD — make Atari ST research recordings accessible in a supported format.

No Emulator Required

Convert AVR files without an Atari ST emulator or SoX command line. The entire process runs in your web browser.

Secure Processing

Uploaded AVR files are deleted immediately after conversion. Output files are purged within 24 hours.

How to convert AVR 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

AVR (Audio Visual Research) is an audio format that originated on the Apple Macintosh around 1989, created by the Audio Visual Research company for their editing and synthesis tools. It stores raw audio samples preceded by a fixed-length header containing sample rate, bit depth (8 or 16 bits), channel configuration, and loop point markers. Unlike complex container formats, AVR uses a flat binary structure with no compression, preserving the full waveform quality at the expense of larger files. The format served professional Macintosh audio workstations during the late 1980s and early 1990s, when the Mac platform dominated creative computing. One advantage is uncompressed storage guaranteeing zero artifacts and perfect signal integrity through editing operations. Native loop markers represent another feature, letting sound designers define seamless repetition points within the file — ahead of its time for sample-based music production. Tools like SoX maintain AVR support, ensuring archivists can access and convert these legacy recordings. While eclipsed by WAV and AIFF, AVR remains a notable piece of early digital audio history.
Initial release: 1989
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 AVR to CVSD?

CVSD is used in military secure voice. Converting AVR to CVSD serves specialized communication hardware.

What can open CVSD files?

SoX and military communication devices handle CVSD.

What is the AVR format?

AVR (Audio Visual Research) is an audio format developed for the Atari ST computer. It was used in academic and research audio applications.

Is AVR widely supported today?

AVR is a niche legacy format. SoX and Audacity can read it on modern systems, but mainstream media players do not support it.

Can I convert multiple AVR files at once?

Yes. Upload several AVR recordings and batch-convert them all simultaneously — efficient for processing research audio libraries.