Moving from Silk to Satin
Office 365 notification MC267133, updated July 30, describes the introduction of Teams music mode to the Teams desktop client to improve the ability to transmit high quality music in Teams meetings and calls. This is Microsoft 365 roadmap item 83520 and Microsoft is rolling out the new feature to tenants in late August with the intention of completing the deployment in late September. The addition of music mode matches the “high-fidelity, professional-grade audio” available on Zoom.
Music mode is enabled by the Satin codec (coder/decoder), introduced by Microsoft in February 2021 to replace the Silk codec (developed by Skype). According to Microsoft, Satin can “deliver super wide band speech starting at a bitrate of 6 kbps, and full-band stereo music starting at a bitrate of 17 kbps, with progressively higher quality at higher bitrates.” To be able to deliver high quality sound over networks where packet loss and low performance is an ongoing fact of life, Satin “uses a deep understanding of speech production, modelling and psychoacoustics to extract and encode a sparse representation of the signal. To further reduce the required bitrate.” I am no audiophile, but Microsoft’s description of the development of Satin can be summed up by saying that a heap of analysis and modelling delivered a new codec capable of transmitting high-quality sound over networks where this wasn’t possible before.
Going back to music mode, Microsoft says that “users will be able to conduct online music lessons, transmit music performances, or other non-speech content.” The reason why is that the Satin codec can transmit music in a way that sounds good where it just wasn’t possible in the past.
Adaptive Sampling, Controls, and Devices
Network throughput tends to fluctuate over time, especially on Wi-Fi or cellular networks. This doesn’t matter so much for voice and video (Teams mobile clients can configure a reduced data usage mode), but it does for high-fidelity music playback. When music mode is used, Teams adjusts the sampling rate automatically up to 32 kHz at 128 kbps using the available bandwidth to deliver the best possible sound quality (the transmission of acceptable human voices requires a much lower bitrate). The lowest bitrate for good quality sound is 48 kbps. Because sound quality is linked to available bandwidth, Microsoft recommends that you use music mode only when connected to wired networks. I haven’t noticed any issues using music mode in calls on my home office Wi-Fi network.
In environments like a studio with low background noise and microphone control, users (including guests joining calls in other tenants) can control the audio stream further by turning off noise cancellation and disabling echo cancellation if using closed back headphones. If using professional microphones with external gain adjustment, you can disable the auto-adjust microphone sensitivity setting.
On the other hand, for meetings hosted from home offices or conference rooms, you’ll probably leave these features turned on.
To use high fidelity music in Teams meetings or calls, Microsoft recommends professional equipment. They don’t like Bluetooth headsets, probably because the quality delivered to something like Apple AirPods would not be good. However, that also rules out the expensive Surface Headphones 2 (with “rich Omnisonic sound”), which I bought recently and enjoy using. I wonder how many of the headsets featured on Microsoft’s site qualify? On the upside, Microsoft says that the built-in microphones and speakers on the Surface Book will deliver “a good sound experience.”
Using Music Mode
The important thing to realize about using music mode is that you must enable the feature in Teams settings before you join a call or meeting (Figure 1). This is where you can decide to enable echo cancellation, noise cancellation, or auto-adjust microphone sensitivity. If you forget to enable music mode before starting a call, you’ll have to leave the call, enable music mode, and restart.
With music mode enabled, you’ll see a music note symbol in the control bar to toggle music mode on and off. You can leave music mode enabled for the entire meeting or turn it off once music finishes to reduce the demand for bandwidth and codec processing. In addition, music mode doesn’t suppress background noise as well as regular mode does.
Important for Some
I don’t think I have ever played music in a Teams call or meeting, so I am not the target audience for this feature. Introducing music mode is a competitive response to one of the biggest competitors for Teams. The Satin codec makes a difference and is a good foundation for music mode. I hope those of you who’ll appreciate the update will enjoy it.