Capstone: NSA for a Content Platform

Platform Profile: StreamVerse

For this capstone, we design the NSA for StreamVerse — a video/audio content platform serving 80M subscribers globally with original content, user-generated content, and live streaming.

Scale Challenges

Content Platform NSA Principles

Target Architecture

flowchart TB
    subgraph L5["🖥️ Client Experience Layer"]
        direction LR
        C1[Smart TV]
        C2[Mobile]
        C3[Web]
        C4[Gaming Console]
    end

    subgraph L4["🎯 Personalization Engine"]
        direction LR
        P1[Recommendation API]
        P2[Home Feed Builder]
        P3[Search & Discovery]
        P4[Notification Engine]
    end

    subgraph L3["🎬 Content Services"]
        direction LR
        S1[Catalog Service]
        S2[Playback Service]
        S3[Creator Platform]
        S4[Rights Engine]
    end

    subgraph L2["📊 Data & ML Platform"]
        direction LR
        D1[Interaction Events]
        D2[Content Graph]
        D3[ML Models]
        D4[A/B Platform]
    end

    subgraph L1["🌍 Global Infrastructure"]
        direction LR
        I1[Multi-Region Cloud]
        I2[CDN / Edge]
        I3[Encoding Farm]
        I4[Observability]
    end

    L5 --> L4
    L4 --> L3
    L3 --> L2
    L2 --> L1

    style L5 fill:#e8f4f4,stroke:#3B9797
    style L4 fill:#f0f4f8,stroke:#16476A
    style L3 fill:#e8f4f4,stroke:#3B9797
    style L2 fill:#f0f4f8,stroke:#16476A
    style L1 fill:#e8f4f4,stroke:#3B9797
                            

Content Pipeline

Content ingestion is the lifeblood of the platform — from upload to playable asset in under 2 hours for standard content:

flowchart LR
    U[Upload] --> V[Validation]
    V --> T[Transcode
Multiple bitrates]
    T --> AI[AI Processing
Tags, thumbnails, chapters]
    AI --> QC[Quality Check]
    QC --> R[Rights Check
Region availability]
    R --> CDN[CDN Distribution
Edge pre-warm]
    CDN --> Live[Available to Users]

    style U fill:#e8f4f4,stroke:#3B9797
    style AI fill:#f0f4f8,stroke:#16476A
    style CDN fill:#3B9797,stroke:#3B9797,color:#fff
    style Live fill:#132440,stroke:#132440,color:#fff
                            

{
  "content_pipeline": {
    "ingestion": {
      "upload_max_size": "200GB",
      "supported_formats": ["MP4", "MKV", "MOV", "ProRes", "H.265"],
      "validation": ["codec_check", "audio_levels", "resolution_verify"]
    },
    "transcoding": {
      "profiles": [
        { "resolution": "4K HDR", "bitrate": "16 Mbps", "codec": "AV1" },
        { "resolution": "1080p", "bitrate": "5 Mbps", "codec": "H.265" },
        { "resolution": "720p", "bitrate": "2.5 Mbps", "codec": "H.264" },
        { "resolution": "480p", "bitrate": "1 Mbps", "codec": "H.264" }
      ],
      "adaptive_streaming": "DASH + HLS"
    },
    "ai_enrichment": {
      "auto_tags": "scene detection + object recognition",
      "thumbnails": "AI-selected best frames per genre",
      "chapters": "audio/scene boundary detection",
      "subtitles": "whisper-based ASR + translation (20 languages)"
    }
  }
}

Recommendation Engine

The recommendation system is StreamVerse's most critical competitive advantage — 80% of viewing hours come from recommendations:

Global Delivery Architecture

Delivering video to 80M users across 45 countries with sub-second start times requires a sophisticated multi-tier delivery system. The fundamental challenge: popular content (top 5% of titles) represents 60% of traffic, while the long tail (bottom 80%) is accessed infrequently but must still be available instantly when requested.

CDN Tiering Strategy

StreamVerse uses a 3-tier CDN architecture that optimizes the cost/performance tradeoff:

• Edge tier (200+ PoPs): Stores top 500 titles per region in SSD cache — covers 60% of stream starts. Sub-100ms response time. Cost: highest per GB but delivers majority of traffic.
• Mid-tier (12 regional nodes): Stores top 50K titles on HDD+SSD mix — covers 35% of starts. 200-500ms first-byte time. Balances cost and coverage.
• Origin (3 master regions): Complete library (2M titles) in object storage — handles remaining 5% (long tail). 500ms-2s first-byte, but pre-fetched to mid-tier on first request.

Adaptive Bitrate & Quality of Experience

Every stream session dynamically adapts video quality based on network conditions, device capability, and user preferences:

• Initial quality: Start with lowest viable quality for instant playback (<1s), then ramp up as buffer fills
• Bandwidth estimation: Client reports throughput every 2 seconds; server-side model predicts next 30 seconds of available bandwidth
• Device-aware: 4K HDR only on capable displays; mobile defaults to 720p (saves bandwidth without visible quality loss on small screens)
• Data saver mode: For users on metered connections, reduces bitrate 50% with AI-optimized encoding that preserves perceptual quality

flowchart TD
    subgraph Origin["Origin (3 regions)"]
        O1[US-East Master]
        O2[EU-West Master]
        O3[APAC Master]
    end

    subgraph MidTier["Mid-Tier CDN"]
        M1[US Regional]
        M2[EU Regional]
        M3[APAC Regional]
        M4[LATAM Regional]
    end

    subgraph Edge["Edge (200+ PoPs)"]
        E1[Edge Cache A]
        E2[Edge Cache B]
        E3[Edge Cache C]
        E4[Edge Cache N]
    end

    subgraph Users["Users"]
        U1[Smart TV]
        U2[Mobile]
        U3[Web]
    end

    Origin --> MidTier
    MidTier --> Edge
    Edge --> Users

    style O1 fill:#16476A,stroke:#16476A,color:#fff
    style M1 fill:#3B9797,stroke:#3B9797,color:#fff
    style E1 fill:#e8f4f4,stroke:#3B9797
                            

Real-Time Personalization

Every user session is personalized in real-time — from homepage layout to thumbnail selection:

Conclusion

Gap Analysis: Current vs Target

Architecture Decision Summary

A content platform NSA is defined by three forces: scale (500M daily streams), personalization (every user gets a unique experience), and global reach (content delivered from 200+ edge locations). The architecture must support all three simultaneously while enabling rapid content experimentation and creator empowerment.