F4V to SLN Converter

Extract Asterisk SLN audio from F4V Flash video

Drop files here. 1 GB maximum file size or Sign Up
to
Facebook Amazon Microsoft Tesla Nestle Walmart L'Oreal

PBX Ready

SLN is the native format for Asterisk PBX — extract audio from F4V ready for VoIP prompts and hold music.

Raw Telephony Audio

SLN provides raw PCM data that Asterisk reads directly — no decoding overhead for your PBX system.

Secure Extraction

F4V uploads are deleted after processing. SLN files are removed from servers within 24 hours.

How to convert F4V 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

F4V is a multimedia container format developed by Adobe Systems as an evolution of the Flash Video ecosystem. Introduced in December 2007 with Flash Player 9 Update 3, F4V is based on the ISO base media file format (MPEG-4 Part 14) and was created to support the H.264 video codec and AAC audio within the Adobe Flash platform. Unlike its predecessor FLV, which used a proprietary container structure, F4V adopts the standardized MP4-compatible atom/box architecture, making it more interoperable with other media tools and workflows. The format supports advanced features including high-profile H.264 encoding, multichannel AAC audio, and timed text for subtitles and captions. F4V represented a strategic move to address the growing demand for H.264 content on the web, as the older FLV container could not efficiently package this newer codec. During its peak years, F4V powered much of the high-quality video content delivered through Flash-based streaming platforms and video players on the web. The container supports both progressive download and dynamic streaming delivery, offering content publishers flexible distribution options. While the decline of Flash Player in favor of HTML5 video has reduced the creation of new F4V content, the MP4-based structure means the contained media streams are readily accessible through modern tools.
Developer: Adobe Systems
Initial release: December 3, 2007
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 F4V to SLN?

SLN is the native raw audio format for Asterisk PBX systems. Extracting from F4V provides audio ready for VoIP telephony setups.

What uses SLN files?

Asterisk PBX systems use SLN as the internal audio format for hold music, IVR prompts, and voicemail greetings.

Is SLN uncompressed?

Yes — SLN is raw signed linear PCM audio without headers or compression, making it the simplest format for Asterisk.

What sample rate does SLN use?

Asterisk SLN files typically use 8 kHz for narrowband or 16 kHz for wideband telephony audio.

Can I batch convert?

Upload multiple F4V files and extract SLN audio from each one simultaneously.