8. Netflix


Design a video streaming service where content can be uploaded and viewers can search and play videos

Functional Requirements
  • Users should be able to create and account and subscribe for a plan.
  • Users should be able to manage multiple profiles.
  • Users should be able to search for a video title.
  • Users should be able to watch a video.
  • Netflix employees should be able to upload a video from backend to make it available on Netflix platform.
Nonfunctional Requirements
  • System should be highly reliable. Any video uploaded should not be lost.
  • System should be highly available.
  • Users should be able to stream videos in Realtime without any lag.
  • Video recommendations

  • Most popular videos

  • Subtitles

  • Grouping of videos (e.g. TV Series, treat each video as independent)

  • Average number of videos users watch daily = 3

  • Number of videos watched per second= (#active users _ #average videos watched daily)/86400 = 3472(100M _ 3/86400)

  • Size of the content stored on a daily basis = #average size of video uploaded every min _ #pairwise combination of resolutions and codecs _ 24_ 60 = 36 TB/day (=2500MB _ 10 _ 24 _ 60)

Estimated Usage

Let’s do some back-of-the-envelope calculations to estimate the bandwidth and storage required.

  • Total number of daily active users = 100 million
  • Average number of videos watched by each user per day = 5
  • Average size of one video = 500 MB
  • Average number of video uploaded per day from backend = 1,000

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