Satin is a lossy

speech codec Speech coding is an application of data compression to digital audio signals containing speech. Speech coding uses speech-specific parameter estimation using audio signal processing techniques to model the speech signal, combined with generic d ...

developed by

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

. Satin was designed to supersede the earlier

Silk Silk is a natural fiber, natural protein fiber, some forms of which can be weaving, woven into textiles. The protein fiber of silk is composed mainly of fibroin and is most commonly produced by certain insect larvae to form cocoon (silk), c ...

codec in their applications, and implements a

neural network A neural network is a group of interconnected units called neurons that send signals to one another. Neurons can be either biological cells or signal pathways. While individual neurons are simple, many of them together in a network can perfor ...

and novel signal processing to improve performance over its predecessor.

Features

Satin is designed to deliver good sound quality despite limited bandwidth or high

packet loss Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is either caused by errors in data transmission, typically across wireless networks, or network congestion.Ku ...

, such as over unreliable WiFi or cellular networks. Satin can produce output bitrates of 6 to 36 kbps, and operates on super-wideband audio (a 32 kHz sampling rate). Sound is encoded by processing a sparse representation of the input, then decoded with the help of a neural network that infers the high frequencies from the low ones. Because neural networks are computationally complex, optimization and vectorization of the network were required to achieve acceptable performance. To improve resilience to packet loss, each packet is encoded independently and the codec has its own packet loss concealment system.

History

Silk was developed by

Skype Skype () was a proprietary telecommunications application operated by Skype Technologies, a division of Microsoft, best known for IP-based videotelephony, videoconferencing and voice calls. It also had instant messaging, file transfer, ...

and can compress wideband speech in 14 kbps. Satin is considered to be Silk's successor, and was initially announced and implemented for

Microsoft Teams Microsoft Teams is a team collaboration platform developed by Microsoft as part of the Microsoft 365 suite. It offers features such as workspace chat, video conferencing, file storage, and integration with both Microsoft and third-party applicat ...

in 2020. As of February 2021, it was used for all two-way calls in both Teams and Skype. According to Microsoft, a future release will add support for music in full-band stereo at bitrates of at least 17 kbps.

Quality

Microsoft claims that Satin's quality is significantly better than Silk, achieving mean opinion scores up to 1.7 points higher in low-bitrate

A/B testing A/B testing (also known as bucket testing, split-run testing or split testing) is a user-experience research method. A/B tests consist of a randomized experiment that usually involves two variants (A and B), although the concept can be also exte ...

. Microsoft also notes that Satin's bitrate savings allows for sending more redundant data to increase resistance to packet loss.{{Cite web , date=2021-02-17 , title=Satin: Microsoft's latest AI-powered audio codec for real-time communications , url=https://techcommunity.microsoft.com/t5/microsoft-teams-blog/satin-microsoft-s-latest-ai-powered-audio-codec-for-real-time/ba-p/2119234 , access-date=2022-07-22 , website=TECHCOMMUNITY.MICROSOFT.COM , language=en

Support

As of February 2021, Skype and Microsoft Teams implemented Satin for all two-person calls, and an expansion to larger Teams meetings was planned.

References

External links