Design a video platform

Hard45 minFree, no account

Petabytes of storage, a transcoding pipeline, and a bandwidth bill that is the architecture.

The question

Design YouTube: upload a video, it becomes watchable at several qualities, millions of people stream it.

Focus on upload, processing and playback. Recommendations are out of scope.

Functional

Upload a video of up to several hours.
It becomes available at multiple resolutions with adaptive switching.
Stream with fast start and seeking.

Non-functional

500 hours uploaded per minute; 1B hours watched per day.
Playback starts in under two seconds anywhere.
Processing a ten-minute video completes within minutes, not hours.

45:00Commit to an answer before you open the solution. Reading it first teaches you to recognise good answers, which is not the skill being tested.

Stuck?

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The worked solution

written by a person · not a grade

Score yourself

0 of 5 marked

Computed egress and made the CDN the centre of the design25
Kept video bytes out of the API tier on upload15
Parallelised transcoding by segment and made it idempotent25
Explained adaptive bitrate as a file layout plus a manifest20
Tiered storage and questioned eager transcoding15

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