Satin is a lossy

speech codec Speech coding is an application of data compression of 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 technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...

. Satin was designed to supersede the earlier

Silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...

codec in their applications, and implements a

neural network A neural network is a network or circuit of biological neurons, or, in a modern sense, an artificial neural network, composed of artificial neurons or nodes. Thus, a neural network is either a biological neural network, made up of biological ...

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.Kur ...

, 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 Packet loss concealment (PLC) is a technique to mask the effects of packet loss in voice over IP (VoIP) communications. When the voice signal is sent as VoIP packets on an IP network, the packets may (and likely will) travel different routes. A pa ...

system.

History

Silk was developed by

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

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 proprietary business communication platform developed by Microsoft, as part of the Microsoft 365 family of products. Teams primarily competes with the similar service Slack, offering workspace chat and videoconferencin ...

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. 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