System designHardsd-g245

Subject Adaptive bitrateLevel Senior–Staff~45 minCommon in Distributed systems interviewsIndustries Technology, Software development

Question

Design the client-side adaptive-bitrate (ABR) system for a global VOD service streaming HLS to 200M devices spanning fiber to congested 3G. The goal is to maximize quality-of-experience: high average bitrate, near-zero rebuffering, few quality switches, and fast startup. Design the rendition ladder, the segment/manifest format, and the ABR decision logic, and explain how the player decides what to fetch next under changing throughput.

What a strong answer looks like

Clarify scale and constraints first. Propose a clean component breakdown, then go deep on the hard parts — data model, bottlenecks, consistency, failure modes — and name the trade-offs you are making.

Learn the concepts

Narrate your design

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Run or narrate your approach, then ask the coach.