AVR to CVS Converter

Transform Audio Visual Research AVR into CVSD telephony

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Research Audio Rescue

Extract audio from the legacy AVR format and convert to CVS — 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 CVS

1

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

2

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

3

Let the file convert and you can download your cvs 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
CVS is a telephony audio encoding based on Continuously Variable Slope Delta modulation, representing voice through a 1-bit delta scheme where step size adapts to track input amplitude. Developed within CCITT (now ITU-T) standards during the 1970s, CVS encodes by comparing each sample to the previous one and outputting a single bit — up or down — with slope magnitude adjusting based on recent bit patterns. This yields extremely low bit rates, typically 16 kbps at 8 kHz sampling, efficient for narrowband voice over constrained channels. CVS files store signed delta-encoded data and are commonly processed using tools like SoX. A significant advantage is bandwidth economy: the 1-bit-per-sample approach demands minimal transmission capacity, essential for military radio links and early digital telephone infrastructure. The adaptive slope mechanism also prevents overload distortion on rapidly changing signals while keeping granular noise acceptable during quiet passages. Though modern wideband codecs have superseded CVS, it retains historical importance and niche utility in legacy telephony and embedded communication devices.
Developer: CCITT / ITU-T
Initial release: 1970

Frequently Asked Questions

Why convert AVR to CVS?

CVS uses CVSD modulation for military voice. Converting AVR targets specialized secure communication systems.

What can open CVS files?

SoX and military telephony systems process CVS files.

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.