MKV to SLN Converter

Extract signed linear audio from MKV for Asterisk PBX

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Asterisk Native

SLN is what Asterisk PBX expects natively. Extract MKV audio directly into the format your phone system uses for prompts and music.

Custom PBX Audio

Turn any video audio into custom hold music, IVR prompts, or greetings for your Asterisk PBX. No telephony tools needed for conversion.

Cloud Extraction

All processing runs on convertio.tools. No Asterisk server access needed for the conversion — upload MKV and download SLN.

How to convert MKV 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

MKV (Matroska Video) is an open-standard multimedia container format developed by the Matroska project, which announced the format in December 2002. Named after the Russian matryoshka nesting dolls, the format is built on the Extensible Binary Meta Language (EBML), a simplified binary variant of XML that provides a flexible and forward-compatible structure. MKV can hold virtually unlimited numbers of video, audio, and subtitle tracks within a single file, supporting codecs from H.264 and HEVC to VP9 and AV1 for video, and AAC, FLAC, Opus, and DTS for audio. A standout feature is comprehensive subtitle support, handling formats from simple SRT text to complex ASS styled subtitles and bitmap-based PGS tracks from Blu-ray discs. MKV also supports chapter markers, attachments (such as fonts needed for styled subtitles), and tagging metadata, making it one of the most feature-rich containers available. The open specification ensures that any developer can implement MKV reading and writing without licensing fees, which has driven widespread adoption across media players, streaming tools, and encoding software. The ability to encapsulate virtually any codec combination in a single, well-organized file has made MKV the preferred container for high-quality video distribution, archival, and personal media libraries.
Developer: Matroska
Initial release: December 6, 2002
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 MKV to SLN?

SLN is Asterisk PBX's native audio format — raw signed linear PCM. Required for custom prompts, hold music, and IVR recordings on Asterisk.

What uses SLN files?

Asterisk, FreePBX, and compatible VoIP PBX systems use SLN for playback. It is the default format for Asterisk sound files.

What sample rate does Asterisk use?

Standard Asterisk uses 8 kHz mono SLN. Wideband configurations use 16 kHz. Match your output to your PBX configuration.

Is SLN compressed?

No — SLN is raw, uncompressed signed linear PCM. Files are straightforward but larger than compressed telephony formats like GSM.

Can I make IVR prompts from MKV?

Yes — extract the audio, and the SLN file can serve directly as an IVR prompt or on-hold recording in your Asterisk PBX system.