This article is part 1.4 of the "21 Thoughts on Video Streaming in 2021"-series.

Will Law's (Chief Architect at Akamai) final 2021 prediction is about Common Media Client Data:

Data analytics continues to grow in importance as it provides the metrics to further optimize delivery. Common Media Client Data (CMCD) will be particularly pivotal as it ties together client client-side QoE and server-side QoS data silos as well as facilitating dynamic delivery optimization by CDNs.

Keep reading to get 1) context and 2) my take.


Common Media Client Data (CMCD) allows "clients" to send "data" to CDNs. CDNs can use the received data to improve their service.

  • To put it differently: the big idea of CMCD is that video apps can send meaningful data to the server hosting their video streams. These servers can then use this data to optimize their service, and proactively fix issues.
  • Without CMCD, you have to analyse your data on video analytics services (e.g. Conviva, Mux, Youbora, MediaMelon), go through logs, identify issues and, if it's related to the CDN, investigate how you can solve it. With CMCD, your life becomes a bit easier.
Example CMCD request from client to CDN as illustrated by Will Law at Miles High Video

Related links:

My take

Data analytics are underrated and underused. Let's hope we, Man and Machine, are more data-driven in 2021.

It will take some time before video apps correctly implement CMCD, as well as the CDNs. Dash.js and Akamai are currently leading the way. I expect some services might start experimenting with CMCD in 2021, but it's too soon to tell whether mass adaptation will happen.