#Lync Question 28: How much bandwidth does the Skype SILK codec use?

Now the it has been announced that Lync is moving to the Skype SILK codec.

Microsoft Lync-Skype connectivity v2 – Adds Video and More

You maybe ask how much bandwidth does SILK use? Previously published was the below figures from Skype in Silk Datasheet


Sadly SILK Super-Wideband (24Hz) is not currently supported by Lync or Skype for Business, it is limited to 16Hz (wideband)

At Lync Conference 2014 in the “Technical deep-dive into Lync-Skype Video” session by Carl Olivier and William Looney the following figures:


So to answer the question 36 kbps when using Wideband and 13 kbps with Narrowband.

For the difference in MOS scores between the figures on the datasheet and Lync Conference I am assuming SILK has been further improved to accommodate Lync integration.

NOTE: MOS figures for SILK narrowband and super wideband are currently not published (I’ve looked everywhere)

During the session Q&A, it was asked whether the Super-Wideband codec will be supported by Lync? Not at the moment and it isn’t a high priority for them.

Lync/Skype v1 calls did not support FEC end-to-end however Lync/Skype v2 calls will use in-band FEC compared to Lync’s out of band FEC. ICEv19 has been added to the Skype client with STUN\TURN for supporting Lync edge servers for media relay as well as H.264 SVC for video interop.

The following figures have been published by Microsoft here

Audio codec Scenario Audio payload bit rate (KBPS) Bandwidth audio payload and IP header only (Kbps) Bandwidth audio payload, IP header, UDP, RTP and SRTP (Kbps) Bandwidth audio payload, IP header, UDP, RTP, SRTP and forward error correction (Kbps)
SILK Wideband Peer-to-peer 36 52 64 100
SILK Wideband Peer-to-peer 26 42 54 80
SILK Wideband Peer-to-peer 20 36 48 68
SILK wideband/narrowband Peer-to-peer 13 29 41 54


Plan network requirements for Skype for Business 2015

SILK Datasheet


UPDATE #1 (14/03/2014) Updated with further information from Lync Conference
UPDATE #2 (18/12/2015) Updated published figures
UPDATE #3 (18/12/2015) it would seem the SILK DataSheet link is now broken, I kept an offline copy so you can get it here

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