Art of Codeartofcode
Lesson 15 of 16

40. Design Video Upload and Streaming (YouTube)

1
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
14
Variations to practise
15
Sources
16
Code lab
40. Design Video Upload and Streaming (YouTube)

Sources

3 min read+10 XP

Source notes

  • YouTube's statement of more than 500 hours of video uploaded every minute (2019): reported by Tubefilter, May 2019. Checked 2026-10-08.
  • HLS segment guidance and adaptive streaming: see Chapter 26's source notes (Apple HLS authoring specification, RFC 8216, MPEG-DASH).
  • ISP-embedded caches: Netflix Open Connect and Google Global Cache documentation.
  • Ladder bitrates, watch hours, encode speed, view thresholds and popularity skew are interview assumptions agreed in Step 1, not figures for any real service. Arithmetic computed 2026-10-08.
  • Resumable upload, segment-parallel transcoding time, ladder storage, ABR vs fixed playback, popularity share and view de-duplication: tested 2026-10-08 (code/ch40_video.py, all checks pass).