Art of Codeartofcode
Lesson 12 of 16

40. Design Video Upload and Streaming (YouTube)

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The interview prompt
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40.1 What do you ask first?
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40.2 How big is this, really?
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40.3 What are the doors?
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40.4 What do we store?
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40.5 What does the whole system look like?
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40.6 How does the upload pipeline work?
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40.7 How does transcoding work?
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40.8 How does adaptive bitrate work?
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40.9 How does CDN delivery work at this scale?
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40.10 How do you count views?
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40.11 What would you say in the last five minutes?
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Score yourself
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Variations to practise
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Sources
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Code lab
40. Design Video Upload and Streaming (YouTube)

40.11 What would you say in the last five minutes?

3 min read+10 XP

Step 6: Wrap-up (5 minutes)

  • Bottlenecks: egress (CDN and ISP caches), transcoding capacity (autoscaled queue workers), storage growth (tiers, fewer qualities for the long tail).
  • Single points of failure: none central: uploads, processing and delivery are all replicated or retryable; the CDN layer is multi-provider.
  • Cost: encode popular videos in better codecs (smaller files save egress), drop unused qualities, move cold originals to archive storage.
  • Next with more time: recommendations, comments, search (Chapter 19), live streaming (Chapter 41), content moderation, and DRM for paid content.

Memory code: "Process in parallel, deliver from the edge, adapt every segment."