TTA to SLN Converter

Encode True Audio as raw SLN for Asterisk online

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PBX Audio

SLN is Asterisk native — converting from lossless TTA produces crystal-clear telephony prompts and messages.

Rate Control

Choose the exact SLN sample rate your Asterisk system needs — 8 kHz or 16 kHz from lossless TTA.

Secure Handling

TTA uploads are erased immediately. SLN telephony audio is purged within 24 hours.

How to convert TTA 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

TTA (True Audio) is a real-time lossless audio compression codec developed by Aleksander Djourik, with its origins tracing back to the early 2000s. The format reconstructs the original PCM stream bit-for-bit upon decoding, guaranteeing that no sonic detail is lost during storage or transfer. TTA handles standard CD-quality audio as well as high-resolution content up to 32-bit integer samples, making it suitable for everyday listening and professional archiving alike. Processing speed is one of TTA's defining strengths — the codec achieves fast encoding and decoding without heavy CPU demands, keeping it lightweight even on older hardware. The file structure supports ID3v1, ID3v2, and APEv2 metadata tags, so track information and album art travel with the audio. Hardware support appeared in several portable players, giving TTA a practical edge over some competing lossless formats. The open-source reference implementation ships under the GNU GPL, encouraging community adoption and third-party integrations. While newer codecs like FLAC have captured a larger share of the lossless audio landscape, TTA continues to serve users who value its simplicity and transparent compression.
Developer: Aleksander Djourik
Initial release: 2003
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

What is SLN?

SLN (Signed Linear) is headerless raw PCM — the native audio format for Asterisk PBX telephony systems.

Why convert TTA to SLN?

Asterisk PBX uses SLN for prompts, hold music, and IVR. Lossless TTA provides clean voice for telephony audio.

What uses SLN?

Asterisk PBX, FreeSWITCH, and open-source telephony platforms use SLN as their internal format.

What sample rate?

Standard Asterisk uses 8 kHz narrowband or 16 kHz wideband. Match your PBX configuration.

Is it secure?

TTA uploads are deleted immediately. SLN outputs are removed within 24 hours.