PVF to SLN Converter

Transcode PVF audio to Asterisk Signed Linear format online

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Cross-Format Audio

Transform PVF recordings into SLN — bringing voice-optimized audio into a format with real-world usability.

Fast Conversion

PVF files are compact — the conversion to SLN completes in just a few seconds on our servers.

Online Conversion

Encoding happens in the cloud — your device stays free while our servers handle the PVF to SLN conversion.

How to convert PVF 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

PVF (Portable Voice Format) is a simple audio file format designed for voice message storage in Linux-based telephony systems, most notably ISDN4Linux and its vbox voicemail application. The format emerged from the European ISDN ecosystem of the late 1990s, when Linux servers increasingly handled PBX and answering machine duties over digital phone lines. PVF files store raw signed 16-bit PCM samples at 8000 Hz mono, preceded by a minimal plain-text header specifying data format and byte ordering. This deliberate simplicity is one of the format's primary strengths — with no compression and a human-readable header, PVF files are trivially easy to parse, pipe, and manipulate using standard Unix tools. The 8 kHz rate matches the Nyquist requirement for telephone-bandwidth speech (300-3400 Hz), making PVF a natural intermediate format for voice processing pipelines. Another advantage is cross-architecture portability: the explicit byte-order declaration means PVF files move between big-endian and little-endian systems without ambiguity. The SoX audio toolkit provides native PVF read/write support, enabling straightforward conversion to modern formats.
Developer: ISDN4Linux Project
Initial release: 1997
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 PVF to SLN?

PVF is a niche telephony voice format. SLN gives your voice recordings broader compatibility with standard players and tools.

What applications open SLN files?

Asterisk PBX and SOX can handle SLN files. Most are available as free downloads for major operating systems.

Is SLN suitable for music?

No. SLN is optimized for speech and voice. Music loses significant quality — use AAC or MP3 for music content instead.

How fast is the conversion?

Processing is fast — PVF files are lightweight and SLN encoding completes in seconds on our server hardware.

Are my files kept private?

Your PVF files are erased after conversion completes. SLN downloads are purged from our servers within 24 hours automatically.

Do I need to register?

No account required. Upload your file, convert, and download the result directly from your browser at convertio.tools.