SLN to SND Converter

Re-encode Asterisk PBX recordings as SND audio online

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Broad Compatibility

Move SLN audio from the Asterisk-specific format into SND — a widely recognized container for general-purpose audio tools.

Cloud Conversion

All processing runs on our servers. No local SoX installation or command-line expertise needed for the SLN to SND conversion.

Privacy First

Your telephony recordings stay private. Uploaded SLN files are erased after processing, SND outputs within 24 hours.

How to convert SLN to SND

1

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

2

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

3

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

About formats

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
SND is a multi-platform audio file extension used across several computing ecosystems since the late 1980s. On Sun and NeXT workstations, .snd files follow the AU format structure — a header with magic number 0x2e736e64, data offset, encoding type, sample rate, and channel count, followed by raw audio. On MS-DOS PCs, the same .snd extension was used by early sound utilities like Sounder and SoundTool for simple 8-bit unsigned PCM recordings. Macintosh systems also employed .snd for sound resources embedded in the resource fork. Because the extension is shared across incompatible formats, audio processing tools typically inspect the file header to determine which variant they are handling: files beginning with the AU magic number are treated as Sun/NeXT audio, while headerless files are interpreted as raw PCM with assumed parameters. The Sun/NeXT variant supports multiple encodings including mu-law, A-law, 8-bit and 16-bit linear PCM, and ADPCM, making it versatile for both speech and general audio. One advantage of the AU-style SND is its self-describing header, which enables any compliant player to determine sample format and rate without external metadata. The MS-DOS SND variants hold historical value as artifacts of the era when Sound Blaster cards first brought digital audio to personal computers. SND files from all platforms can be processed and converted using SoX and other audio tools.
Initial release: 1988

Frequently Asked Questions

Why convert SLN to SND?

SND is a generic sound format used by various audio tools and legacy systems. Converting SLN to SND broadens compatibility beyond Asterisk.

What programs open SND files?

Audacity, SoX, QuickTime, and many Unix audio utilities can open and play SND files natively.

Is SND the same as AU?

SND shares similarities with the AU format and is sometimes used interchangeably, but specific implementations may differ between platforms.

Can I convert multiple files at once?

Upload a batch of SLN recordings and process them all to SND simultaneously in one session.

Is my audio data protected?

SLN uploads are deleted right after conversion, and SND outputs are purged from servers within 24 hours.