Live From The Stadium
Design the live video backend for a global sports platform that broadcasts a stadium match to a worldwide audience, including the chat sidebar that runs next to the player.
Requirements
Functional:
- Ingest one production feed per venue and deliver it to web, mobile, and TV players.
- Adaptive bitrate playback so a phone on 3 Mbps and a TV on 25 Mbps both get a watchable picture.
- A 4 hour rewind window that stays available for the length of the event.
- One live chat room per stream, with moderation, per-user send limits, and replay of recent messages on reconnect.
Non-functional:
- p95 glass-to-glass latency under 10 seconds, p99 under 15 seconds.
- Playback start under 2 seconds, rebuffer ratio under 0.5 percent.
- A sent chat message reaches the room within 2 seconds.
- Survive the loss of one CDN provider or one availability zone mid-event without an operator in the loop.
Scale
- 5,000,000 concurrent viewers at kickoff peak, 12M DAU on match days.
- 3.5 Mbps average sustained per viewer once bitrate selection settles.
- 2 second segments, cut into 500 ms parts, over a 6 step rendition ladder totalling about 12 Mbps.
- Chat: 3,300 messages per second baseline, 33,000 per second in the 20 seconds after a goal, 200 bytes each.
- 5.4 GB of encoded video per stream-hour, roughly 500 events per season.
Out of scope
DRM license issuing, ad insertion, payments and entitlement checks, VOD editing and highlight clipping, and the venue camera and switcher hardware.
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