System designMediumsd-g603

Subject Image video storage deliveryLevel Mid–Senior~40 minCommon in Storage & CDN interviewsIndustries Technology

Question

Design an image and short-video storage + delivery pipeline for a social product. Constraints: millions of uploads/day, every asset needs multiple derivatives (thumbnails, several resolutions, formats like WebP/AVIF/H.264), p95 delivery under 50 ms via CDN, and you want to avoid pre-generating every variant for assets that are never viewed. Cover ingest, derivative generation, and delivery.

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.