Design a Live Streaming Platform
Last updated: March 3, 2025
Quick Overview
Design low-latency live video streaming with real-time comments, gifting, viewer count aggregation, and recording for VOD conversion.
ByteDance
March 3, 202512
4
2,986 solved
Design low-latency live video streaming with real-time comments, gifting, viewer count aggregation, and recording for VOD conversion.
TikTok Live is a major product. Tests understanding of real-time streaming protocols and interactive feature design.
What the Interviewer Expects
- Design low-latency RTMP/WebRTC ingest and transcoding
- Implement real-time comment and gift systems
- Build viewer count aggregation at scale
- Handle stream recording for VOD conversion
- Address latency versus quality trade-offs
Key Topics to Cover
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- How do you achieve sub-3-second end-to-end latency?
- How do you handle stream quality adaptation for viewers on poor connections?
- How do you detect and filter spam comments in real-time?
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Practice System Design ProblemsSample Answer
Ingest and Distribution
Streamer sends video via RTMP to the nearest ingest server. The server transcodes to multiple bitrates in real-time and packages into low-latency HLS ...
Real-Time Features
Comments and gifts flow through a WebSocket gateway. Use pub/sub (Redis Pub/Sub or a custom message broker) to fan out events to all viewers in a stre...
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