8. Design a Video Streaming Platform

The brief

Design an on-demand video platform from resumable upload through transcoding and playback. Explain when a video becomes playable, how viewers select bitrate and how popular content is delivered. Handle failed processing, deletion and a sudden audience spike without assuming live streaming is in scope.

• Upload 100,000 videos/day averaging 500 MB and ten minutes of playback each.
• Serve 1 million concurrent viewers at peak, with average delivered bitrate of 3 Mb/s.
• Offer three playback renditions. Processing can fail and a new video can become popular immediately.

Constraints

Playback startup target≤ 3 seconds

Declare p95 startup time for a cached video on an adequate network; state excluded network conditions.

Playable publication

Expose only complete manifests and ready segments; represent processing failures honestly.

Deletion and cache policy

Define removal from discovery, authorization and cached delivery with explicit propagation limits.

What to cover

1. 01

   Upload and processing states

   Show durable upload, job identity, renditions, retries and publication.

2. 02

   Playback path

   Describe manifests, segmented delivery, bitrate selection and access checks.

3. 03

   Capacity estimate

   Calculate ingress storage, approximate processing demand and peak egress bandwidth.

4. 04

   Spike and outage walkthrough

   Trace a failed rendition and a cold popular video; compare origin protection strategies.

Worked designs

Explore the architecture and decisions, then build on an example with Coach.

Official design

Design a Video Platform like YouTube

Upload tens of gigabytes and stream to any screen: resumable multipart uploads, a chunked transcoding DAG, adaptive bitrate over a CDN: one-hour boards for junior, senior and staff, with the theory behind them.

Explore the design

Review rubric

AI feedback uses these criteria. Scores are practice feedback.