Overview

scheng enables developers to construct programmable video instruments using:

• Directed signal graphs
• GPU shader execution
• Real-time parameter control
• Structured runtime planning

Rather than being a fixed VJ application, scheng is an engine and SDK for building custom instruments with predictable execution behavior. It provides a graph-based execution model, explicit shader and node contracts, and a modular SDK surface for building deterministic, extensible visual systems.

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Architecture at a Glance

scheng is organized as a multi-crate workspace separating core responsibilities:

1. Graph Layer
   Declarative signal topology and node relationships.

2. Runtime Layer
   Frame planning and deterministic execution.

3. Shader Contracts
   Explicit interfaces between nodes and GPU forms.

4. Control Inputs
   OSC, keyboard, transport, and external state.

5. Output Targets
   Render targets and external integrations.

Each layer is intentionally isolated to enforce clarity, extensibility, and real-time safety.

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Core Concepts

Graph
A declarative structure defining signal flow between nodes.

Node
A unit of execution implementing a defined contract. Nodes consume and produce textures.

Instrument
An executable built on the scheng SDK that wires graph, runtime, and controls.

Runtime
The system responsible for frame scheduling and dispatch.

Transport
Time and playback control propagation through the graph.

Control Surface
External systems that modify node parameters in real time.

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Design Principles

• Explicit execution contracts
• Clear separation of concerns
• Deterministic frame behavior
• Extensibility without runtime modification
• GPU-first architecture

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What scheng Is Not

scheng is not:

• A GUI-based patch editor
• A turnkey VJ application
• A video editing suite
• A high-level scripting framework

It is a programmable engine for constructing video instruments.

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