computer science

SILK

SILK is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand SILK rather than just read about it. In short: SILK is an audio compression format and audio codec developed by Skype Limited, now a Microsoft subsidiary. It was developed for use in Skype, as a replacement for the SVOPC codec.

Key takeaways

SILK belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect SILK to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of SILK from memory before moving on to harder problems.

Reference excerpt

SILK is an audio compression format and audio codec developed by Skype Limited, now a Microsoft subsidiary. It was developed for use in Skype, as a replacement for the SVOPC codec. Since licensing out, it has also been used by others. It has been extended to the Internet standard Opus codec.

Details

Skype Limited announced that SILK can use a sampling frequency of 8, 12, 16 or 24 kHz and a bit rate from 6 to 40 kbit/s. It can also use a low algorithmic delay of 25 ms (20 ms frame size + 5 ms look-ahead). The reference implementation is written in the C programming language. The codec technology is based on linear predictive coding (LPC). The SILK binary SDK is available.

License The SILK codec is patented and licensed separately from the SILK SDK. The codec is open-source, freeware, available royalty free with restrictions on use and distribution. The SDK was initially available only by application by giving details of name, address, phone, and description of how SILK will be used. As of 2012 (version 1.0.9) the SDK can by downloaded without application, but the licence restricts the use to internal evaluation and testing purposes only, excluding software distribution or use in any commercial product or service.

History SILK replaces the previously used SVOPC in Skype, which was a in-house solution to replace the iSAC and iLBC, which again were licensed from Global IP Solutions. The SILK codec was a separate development branch from SVOPC and it has been under development for over 3 years. It was announced in January 2009 on the Consumer Electronics Show and was integrated in Skype for the first time in version 4.0 beta 3 from January 7, 2009, with the final version being released on February 3. On March 3, 2009, Skype Limited announced that the SILK codec will be available soon under a royalty free license to third-party software and hardware developers. The first draft of the SILK Speech Codec description was submitted to the Internet Engineering Task Force (IETF) as a candidate for the standardisation of a new Internet wideband audio codec on July 6, 2009, thereby openly publishing the format along with the source code of the reference implementation. There is also a first draft of the RTP Payload Format and File Storage Format for SILK Speech and Audio Codec.

Opus

SILK is a foundation (with CELT) of the hybrid codec Opus (at the time called "Harmony") that was submitted to the IETF in September 2010, and was chosen as the final candidate for the new standard. Opus was published as an IETF proposed standard in September 2012 and Skype announced that they would be using Opus going forward.

Usage The stable version of SILK was first introduced in Skype 4.0 Beta 3 for Windows, released on January 7, 2009. The final version of Skype 4.0 was released on February 3, 2009. On March 22, 2011, the Steam game platform started using the SILK codec for its integrated in-game and community voice chat. Later on 14 April, in Team Fortress 2, the codec was implemented into the in-game voice chat. On January 29, 2013, the updated to SteamPipe platform GoldSrc started using the SILK codec for the in-game voice chat. It has been found being used on Zoom.

Illustrations

Worked examples

Example 1 — a first encounter with SILK

Start with the simplest possible case. Write down what SILK claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to SILK before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about SILK ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of SILK

In research: SILK appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses SILK in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: SILK is common in secondary-school and first-year university syllabi. It links to neighbouring topics Audio codecs, Free software programmed in C++, Microsoft free software, so understanding it makes those chapters shorter.
In everyday life: Look for SILK outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “SILK” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study SILK in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what SILK means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain SILK out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is SILK in simple terms?

SILK is an audio compression format and audio codec developed by Skype Limited, now a Microsoft subsidiary. It was developed for use in Skype, as a replacement for the SVOPC codec.

Why does SILK matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study SILK?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on SILK.