CVS to AU Converter

Move your CVS audio to AU format in seconds online

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Format Upgrade

CVS recordings become far more usable as AU. The conversion unlocks simple well-documented structure that CVS cannot provide.

No Installation

Skip the software installations. This browser-based tool handles CVS to AU conversion entirely online, from any modern browser.

Works Everywhere

No platform restrictions. Convert your CVS audio to AU on any operating system through a standard web browser.

How to convert CVS to AU

1

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

2

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

3

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

About formats

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 Though modern wideband codecs have superseded CVS, it retains historical importance and niche utility in legacy telephony and embedded communication devices.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
AU is an audio file format introduced by Sun Microsystems for its Unix workstations and the NeXT platform. It features a minimal 24-byte header specifying data offset, size, encoding type, sample rate, and channel count, followed by the audio payload. AU supports numerous encodings, including uncompressed linear PCM at various bit depths, mu-law and A-law companding (logarithmic compression used in telephone systems), and several ADPCM variants. This versatility made AU a workhorse across early Unix environments, web audio (Java applets defaulted to AU), and telephony applications. One advantage is simplicity: the compact header and straightforward structure make it trivial to parse, generate, and stream programmatically. The built-in mu-law option provides another benefit, delivering reasonable voice quality at just 8 KB per second — half the rate of 16-bit uncompressed audio — invaluable when storage and bandwidth were scarce. Although modern formats have largely supplanted AU in consumer applications, it retains a foothold in scientific computing and audio processing pipelines where minimal overhead and reliable cross-platform behavior are valued.
Developer: Sun Microsystems
Initial release: 1992

Frequently Asked Questions

What is the benefit of converting CVS to AU?

CVS suffers from not recognized by modern audio software. AU offers cross-platform Unix support.

What programs can play AU?

You can open AU with VLC, Audacity, SoX, and Unix/Linux media players.

Is there quality loss from CVS to AU?

No quality is lost. AU stores audio without additional compression, so your CVS recording carries over at full original fidelity.

Does this converter work on mobile devices?

Absolutely. Since conversion happens in the browser, any device with internet access and a modern browser will work.

How long does CVS to AU conversion take?

Most conversions finish within seconds. Processing time depends on recording length, but the cloud-based engine handles it quickly.

What if my CVS recording is very long?

The converter handles recordings of various lengths. For very large or numerous files, premium plans provide extended capacity.