Widevine is Google's DRM system, built into Android, Chrome, Android TV, and a vast range of third-party devices and smart TVs. It is one of the three DRMs a platform must support (with PlayReady and FairPlay) to reach every screen, and it is the workhorse for the Android and Chrome ecosystem.
Widevine defines security levels that matter enormously for what content you may serve. L1 means all crypto and media processing happen inside the device's hardware trusted execution environment — required by studios for HD/4K. L3 means processing happens in software, with no hardware backing, and is typically capped to standard definition. A platform must read the device's Widevine level and apply policy accordingly, downgrading resolution where only L3 is available.
On the wire Widevine uses Common Encryption (cenc, increasingly cbcs) and integrates with browsers through EME and the Widevine Content Decryption Module. Its license server issues the keys and policy after checking entitlement.
