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

Netflix switched all Live events from CBR (Constant Bitrate) to VBR (Variable Bitrate) encoding on January 26, 2026. VBR adapts bitrate to scene complexity, reducing average bytes delivered by ~15% and peak traffic by ~10%, while cutting rebuffers by ~5%. The main engineering challenge was preventing servers from over-admitting sessions during low-bitrate phases only to be overwhelmed when complex scenes spike bitrate. The fix was reserving capacity based on nominal bitrates rather than current traffic. Netflix also retuned the bitrate ladder using VMAF comparisons to ensure VBR quality matched CBR, slightly raising nominal bitrates on low-end streams. Future work includes using actual segment sizes in adaptive bitrate algorithms and applying smarter capacity reservation discounts.