SNDT to SLN Converter

Online SNDT to SLN conversion — fast and simple

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Secure Conversion

All SNDT to SLN conversions happen over encrypted connections. Source files are deleted immediately, and output is purged within 24 hours.

Multiple Files

No need to convert SNDT recordings one by one. Upload an entire batch and get all your SLN results simultaneously.

True to Source

Your SNDT recording converts to SLN with maximum accuracy. The conversion engine preserves audio characteristics from the original file.

How to convert SNDT to SLN

1

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

2

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

3

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

About formats

SNDT is the audio format associated with Sndtool, an early MS-DOS sound utility from the early 1990s that appeared alongside the spread of Sound Blaster cards in PCs. Unlike the headerless Sounder format, SNDT files include a brief header with the sample rate and data length — a meaningful improvement that let playback software determine timing automatically. Audio data is stored as 8-bit unsigned PCM, typically at 8000 to 22050 Hz in mono. Sndtool functioned as a simple waveform recorder and player, often distributed as shareware or bundled with sound card drivers. A key advantage over competing DOS audio formats was this self-describing header, which eliminated the guesswork of playing unfamiliar files — a real problem before standardized multimedia frameworks existed. The format was also efficient to decode, requiring no decompression and minimal CPU overhead on the 286 and 386 processors of the time. SNDT files served as building blocks for early PC games and multimedia presentations, where developers needed reliable audio across the limited Sound Blaster hardware ecosystem. Today, SNDT survives in retro software archives and is supported by SoX for conversion to modern formats.
Developer: Sndtool (MS-DOS)
Initial release: 1992
SLN (Signed Linear) is a headerless raw audio format storing 16-bit signed linear PCM samples at 8000 Hz mono, most closely associated with Asterisk — the open-source PBX framework developed by Digium (now Sangoma Technologies). Within Asterisk, SLN serves as the native internal audio representation: every codec transcoding operation passes through signed linear as an intermediate step. This makes SLN the backbone of Asterisk's codec translation architecture. The format contains nothing but raw samples — no headers, no metadata, no framing — so parameters must be known in advance. While this lack of self-description might seem limiting, it is actually an advantage in telephony where sample format is fixed by convention and every overhead byte matters across thousands of simultaneous channels. The 8000 Hz rate aligns with the G.711 standard for traditional telephony, capturing the full 300-3400 Hz voice band. Asterisk also supports extended variants (sln16, sln32, sln48) for wideband audio. SLN files require no decoding — just direct memory mapping — making them ideal for real-time mixing, conferencing, and prompt playback in high-density VoIP environments.
Initial release: 1999

Frequently Asked Questions

Why convert SNDT to SLN?

SNDT audio is inaccessible without specialized vintage tools. Signed Linear is the native format for Asterisk PBX — needed when creating audio prompts for telephony servers.

What software plays SLN?

Open SLN with Asterisk PBX system or SoX. These tools handle the format natively and provide reliable playback.

Can I convert multiple SNDT recordings at once?

Yes — upload several SNDT files and convert them all to SLN simultaneously. Batch conversion saves significant time on collections.

Will audio quality degrade during conversion?

Quality depends on the target codec. Lossless formats keep every sample from your SNDT source. Lossy codecs apply minimal compression.

Does the converter work with damaged recordings?

The converter reads whatever audio data is available in the SNDT file. Severely corrupted sections may not transfer, but valid data converts.

Is my data encrypted during transfer?

All uploads and downloads use encrypted HTTPS connections. Your SNDT audio and the resulting SLN output are protected throughout the process.