Smarter Live Streaming at Scale: Rolling Out VBR for All Netflix Live Events

Netflix explains their January 26, 2026 transition from CBR to VBR encoding for all Live events, detailing the engineering challenges and solutions involved.

• •VBR adjusts bitrate dynamically to scene complexity, using fewer bits on simple scenes (e.g., waiting rooms) and more on complex ones (e.g., confetti shots), unlike CBR which holds a fixed rate
• •The switch achieved ~5% fewer rebuffers per hour, ~15% fewer bytes transferred on average, and ~10% reduction in traffic at peak minute across multiple A/B tests
• •VBR introduces a delivery stability risk: servers appear under-utilized during low-bitrate dips and accept extra sessions, then become overloaded when scene complexity spikes bitrate back up
• •Netflix addressed this by reserving server capacity based on each stream's nominal bitrate rather than its current traffic, keeping steering behavior consistent with CBR