GSRT to AU Converter

Re-encode Grandstream VoIP GSRT audio as AU online

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Format Freedom

Convert proprietary GSRT audio to AU — Unix audio format accessible on modern platforms and devices.

Online Conversion

No audio tools required locally. Upload GSRT, get AU back — all processing runs on our cloud infrastructure.

Any Platform

Convert from any device with a browser — desktops, laptops, tablets, and smartphones all work perfectly.

How to convert GSRT 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

GSRT is a purpose-built ringtone format developed by Grandstream Networks for its line of IP phones and VoIP endpoint devices. Each file begins with a fixed-size header identifying sample rate (typically 8 kHz or 16 kHz), bit depth, and payload length, followed by PCM or mu-law encoded audio data optimized for the small speakers found in desk phones. The design prioritizes minimal decode complexity — Grandstream handsets run on embedded processors with limited memory, so the format avoids transform stages or complex bitstream parsing. Ringtones are usually provisioned through a web management interface or a centralized configuration server, letting IT administrators push branded audio to an entire fleet of phones at once. Although GSRT occupies a narrow niche within enterprise VoIP telephony, its straightforward binary layout means conversion tools can map the payload directly to WAV with minimal effort. Key advantages include rock-solid playback reliability on Grandstream hardware, negligible latency from file read to speaker output, and seamless integration with the provisioning ecosystem for company-wide ringtone deployment.
Initial release: 2002
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

Why convert GSRT to AU?

GSRT only works on Grandstream IP phones. AU lets you use the audio outside the Grandstream ecosystem on standard devices.

What applications open AU files?

SOX, Java applications, and Unix/Linux systems can handle AU files. Most are available as free downloads for major operating systems.

How is the AU audio quality?

AU provides good quality at standard settings. The output clarity depends on the original GSRT recording quality.

How fast is the conversion?

Both formats produce manageable file sizes. The GSRT to AU conversion finishes almost instantly on our infrastructure.

Are my files kept private?

GSRT uploads are removed right after processing. All AU output files are cleaned from servers within 24 hours.