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System Design: Netflix-Like Video Streaming Platform
Context
Design a large-scale video streaming platform that supports web, mobile, and TV clients for millions of concurrent viewers worldwide. The system should prioritize availability, low-latency playback, security, and cost efficiency.
Assumptions
- Peak: 5–10 million concurrent streams globally.
- Target startup latency < 2 seconds; low rebuffering; 99.9%+ availability for playback.
- Mix of on-demand VOD content; live streaming is not a primary requirement, but optional considerations are welcome.
Requirements
Design the system to cover the following components:
- User Authentication and Profiles: Implement features for sign-in, session management, multi-factor authentication (MFA), device limits, parental controls, and support for multiple profiles per account.
- Content Catalog and Metadata: Manage information such as titles, seasons/episodes, genres/tags, content availability windows, regional rights, and various subtitle/audio tracks.
- Search and Personalized Recommendations: Provide full-text search capabilities, browse pages, personalized content rows, and effective cold-start handling for new users.
- Video Ingestion and Transcoding Pipeline: Design a secure content uploader, quality control (QC) processes, per-title encoding, thumbnail generation, caption processing, and packaging into HLS/DASH formats.
- DRM and Adaptive Bitrate Streaming: Integrate Digital Rights Management (DRM) solutions like Widevine, FairPlay, and PlayReady, along with license services. Support Common Media Application Format (CMAF), HLS/DASH manifests, and optionally Low-Latency HLS (LL-HLS).
- CDN and Edge Caching Strategy: Implement a multi-CDN approach, edge authorization, origin shielding, and strategies for cache warming and purges.
- Storage and Geo-Replication: Define storage for master video files versus various renditions, object storage layout, lifecycle tiers for content, and cross-region replication strategies.
- Playback Session Management: Handle session creation, enforce concurrency limits, manage heartbeats, collect Quality of Experience (QoE) metrics, and enable resume playback functionality.
- APIs and Service Discovery: Design external API gateways, internal gRPC communication, schema management, rate limiting, idempotency, and potentially a service mesh.
- Multi-Region Failover and Data Consistency: Address active-active versus active-passive deployment models, routing mechanisms, and data models with appropriate consistency choices.
- Observability and A/B Testing: Implement metrics, traces, and logs; define QoE Service Level Objectives (SLOs); establish an experimentation platform; and set up guardrails.
- Cost Optimization: Detail strategies for encoding ladder optimization, codec choices, storage lifecycle management, CDN offload techniques, and compute efficiency.
Deliver a high-level architecture and justify key trade-offs. Include back-of-the-envelope capacity estimates and call out pitfalls and edge cases.
AI interview prep
Core dilemma
Delivering a highly available, low-latency, secure, and personalized video streaming experience globally to millions of concurrent users, while aggressively optimizing for cost efficiency across content delivery, storage, and processing.
Mid-level signals3
Senior signals5
Red flags5
3 tradeoffs and 3 stress tests locked
Interview prep
Unlock the interviewer X-Ray rubric, tradeoff matrix, stress tests, clarifying questions, and key concepts.
System Design: Netflix-Like Video Streaming Platform
Context
Design a large-scale video streaming platform that supports web, mobile, and TV clients for millions of concurrent viewers worldwide. The system should prioritize availability, low-latency playback, security, and cost efficiency.
Assumptions
- Peak: 5–10 million concurrent streams globally.
- Target startup latency < 2 seconds; low rebuffering; 99.9%+ availability for playback.
- Mix of on-demand VOD content; live streaming is not a primary requirement, but optional considerations are welcome.
Requirements
Design the system to cover the following components:
- User Authentication and Profiles: Implement features for sign-in, session management, multi-factor authentication (MFA), device limits, parental controls, and support for multiple profiles per account.
- Content Catalog and Metadata: Manage information such as titles, seasons/episodes, genres/tags, content availability windows, regional rights, and various subtitle/audio tracks.
- Search and Personalized Recommendations: Provide full-text search capabilities, browse pages, personalized content rows, and effective cold-start handling for new users.
- Video Ingestion and Transcoding Pipeline: Design a secure content uploader, quality control (QC) processes, per-title encoding, thumbnail generation, caption processing, and packaging into HLS/DASH formats.
- DRM and Adaptive Bitrate Streaming: Integrate Digital Rights Management (DRM) solutions like Widevine, FairPlay, and PlayReady, along with license services. Support Common Media Application Format (CMAF), HLS/DASH manifests, and optionally Low-Latency HLS (LL-HLS).
- CDN and Edge Caching Strategy: Implement a multi-CDN approach, edge authorization, origin shielding, and strategies for cache warming and purges.
- Storage and Geo-Replication: Define storage for master video files versus various renditions, object storage layout, lifecycle tiers for content, and cross-region replication strategies.
- Playback Session Management: Handle session creation, enforce concurrency limits, manage heartbeats, collect Quality of Experience (QoE) metrics, and enable resume playback functionality.
- APIs and Service Discovery: Design external API gateways, internal gRPC communication, schema management, rate limiting, idempotency, and potentially a service mesh.
- Multi-Region Failover and Data Consistency: Address active-active versus active-passive deployment models, routing mechanisms, and data models with appropriate consistency choices.
- Observability and A/B Testing: Implement metrics, traces, and logs; define QoE Service Level Objectives (SLOs); establish an experimentation platform; and set up guardrails.
- Cost Optimization: Detail strategies for encoding ladder optimization, codec choices, storage lifecycle management, CDN offload techniques, and compute efficiency.
Deliver a high-level architecture and justify key trade-offs. Include back-of-the-envelope capacity estimates and call out pitfalls and edge cases.