An end user's media player understands playback better than a content delivery network can from its limited server-side data. Common Media Client Data (CMCD) is an open specification that lets you include this expanded playback information as metadata in requests from your media player.

What it does

This behavior lets you leverage CMCD to prefetch segment URLs from your origin sever to speed up delivery. There are some prerequisites and steps you need to follow to add it. See the Adaptive Media Delivery documentation for complete details.