Dev Blog

Behind the scenes of Sim RaceCenter — how we build AI-powered broadcast production for sim racing.

Dev Log

Engineering narratives, post-mortems, and development updates.

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Lifting the Hood: How Sim RaceCenter Reads iRacing Telemetry

A deep dive into how our Director App reads live iRacing telemetry using Node.js, Shared Memory, and Fast FFI — plus how you can build your own client.

·Sim RaceCenter Team·4 min read
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From Raw Telemetry to Race Events: The Publisher Integration

How the Director app's iRacing extension was upgraded from streaming raw telemetry to publishing structured race events — and how this fundamentally changes what the AI Director knows about a race in progress.

·Sim RaceCenter Team·13 min read
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Closing the Template Quality Gap: What Live Testing Revealed About AI Broadcast Direction

After weeks of live testing the AI Director, we identified systematic gaps in template selection, timing, and content quality. This post documents what we found and designs five improvements — including Race Director's Notes and Session Summaries — to close the gap between technically correct sequences and compelling broadcast storytelling.

·Sim RaceCenter Team·18 min read
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When the AI Director Goes Silent: Debugging a Live Executor Cascade

A post-mortem of a production incident where parse failures, rate limits, and connection timeouts cascaded to take the AI Director offline during a live broadcast.

·Sim RaceCenter Team·3 min read
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The PortableSequence Spec: One Format to Run Them All

How we designed a single wire format that carries every broadcast sequence — AI-generated, operator-built, or injected — from cloud to camera.

·Sim RaceCenter Team·5 min read
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The Sequence Execution Stack

How the Director App processes broadcast sequences through a three-layer stack — from queue management and variable resolution in the Scheduler, through step dispatch in the Executor, to intent handlers in extensions.

·Sim RaceCenter Team·6 min read
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Director Orchestrator & Session Lifecycle

How the Director App manages sessions and coordinates its subsystems through a mode-based finite state machine — from discovery through check-in to active broadcast direction.

·Sim RaceCenter Team·7 min read
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How the AI Director Selects Sequence Templates

A deep-dive into the two-phase Planner–Executor architecture that drives real-time broadcast decisions in Sim RaceCenter.

·Sim RaceCenter Team·7 min read
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iRacing Broadcast Knowledge Base

Domain knowledge for AI-powered broadcast direction of iRacing sim racing events — covering the platform, race procedures, camera systems, and professional directing principles.

·Sim RaceCenter Team·16 min read
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Race Control API

A technical overview of the serverless backend that powers Sim RaceCenter — the AI Director pipeline, data model, and security architecture.

·Sim RaceCenter Team·6 min read
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The iRacing Telemetry Pipeline

How the Director App reads iRacing shared memory via koffi FFI to extract session data, telemetry variables, camera groups, and live race state — powering the AI's understanding of what's happening on track.

·Sim RaceCenter Team·8 min read
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The Director Extension System

How the Director App's extension architecture enables modular integration with iRacing, OBS, Discord, and YouTube through a two-tier registry, intent handlers, and a sandboxed utility process.

·Sim RaceCenter Team·7 min read
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The Director Application

How the Director desktop app serves as the on-machine broadcast execution engine — managing extensions, executing sequences, and coordinating local integrations in real time.

·Sim RaceCenter Team·5 min read
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Sim RaceCenter: AI-Powered Broadcast Production for Sim Racing

An overview of Sim RaceCenter — what it does, who it's for, and how it transforms live sim races into professional-quality broadcasts.

·Sim RaceCenter Team·4 min read