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Openai·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
Jun 2026

Summary

System design round at OpenAI for a software engineer role. One question, big scope. I left feeling like I'd barely scratched the surface of what they were probably looking for.

Questions Asked (1)

Q1

Design a text-to-video generation system similar to Sora.

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

This one is massive and I underestimated the scope going in.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then propose a high-level architecture that separates the text encoder, video generation model, and serving infrastructure. Dive into key components like diffusion transformers, spatiotemporal compression, and scalable inference, while discussing trade-offs in quality, latency, and cost.

Pro tip: Emphasize how you would handle the massive compute and memory demands of video generation, such as using latent diffusion and model parallelism, and discuss how to ensure safety and alignment in generated content.

1. Clarify Requirements and Constraints

Ask about expected video length, resolution, generation time, and scale (e.g., number of requests per day). Clarify if the system needs to support fine-tuning or customization.

2. High-Level Architecture

Outline the main components: text encoder (e.g., CLIP), video generation model (e.g., diffusion transformer), and serving layer. Explain how they interact and the data flow.

3. Deep Dive into Model and Training

Discuss the model architecture, such as using a diffusion model in latent space with spatiotemporal attention. Cover training data, compute requirements, and techniques like progressive distillation for faster inference.

4. Serving and Scaling

Describe how to deploy the model for low-latency inference, including optimizations like model parallelism, quantization, and caching. Address load balancing and autoscaling.

5. Trade-offs and Safety

Discuss trade-offs between quality, speed, and cost. Mention safety measures like content filtering and watermarking to prevent misuse.

Key Points to Mention

  • Use of latent diffusion models to reduce computational load by operating in a compressed latent space.
  • Spatiotemporal transformers to capture both spatial and temporal dependencies in video.
  • Techniques for efficient inference such as model parallelism, quantization, and distillation.
  • Scalable serving infrastructure with load balancing, caching, and autoscaling.
  • Safety and alignment considerations, including content moderation and watermarking.
  • Trade-offs between video quality, generation speed, and cost, and how to balance them based on requirements.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.