38 lines
1.6 KiB
Markdown
38 lines
1.6 KiB
Markdown
|
# Architecture
|
||
|
|
|
||
|
|
## Decision: modular engine first
|
||
|
|
|
||
|
|
The processing graph is the common model for audio sources, instruments,
|
||
|
|
effects, mixers, and outputs. The sequencer produces time-based content and
|
||
|
|
events consumed by graph nodes. The default workspace remains sequencer-first;
|
||
|
|
the graph editor is an advanced view of the same project.
|
||
|
|
|
||
|
|
## Layers
|
||
|
|
|
||
|
|
1. **FLTK/C++ GUI:** input, drawing, windows, view state.
|
||
|
|
2. **C core:** project model, commands, parameters, persistence, validation.
|
||
|
|
3. **C engine:** prepared processing graph, DSP, transport timing, event delivery.
|
||
|
|
4. **Backend:** hardware and system audio/MIDI integration.
|
||
|
|
|
||
|
|
The GUI must not directly modify engine internals. It calls a stable C API.
|
||
|
|
|
||
|
|
## Graph execution
|
||
|
|
|
||
|
|
The first implementation should reject cycles. Compile a graph off the audio
|
||
|
|
thread: validate, topologically sort, determine buffer requirements, allocate
|
||
|
|
resources, and publish a prepared immutable execution plan. The audio thread
|
||
|
|
must not traverse a graph being edited.
|
||
|
|
|
||
|
|
The current scaffold is deliberately incomplete: `xt_graph_process_offline()`
|
||
|
|
validates the graph and applies gain nodes in insertion order. It is a test
|
||
|
|
placeholder, not the final graph execution algorithm.
|
||
|
|
|
||
|
|
## Ownership and threads
|
||
|
|
|
||
|
|
- GUI thread owns FLTK widgets and view state.
|
||
|
|
- Project/control thread owns mutable project data and graph compilation.
|
||
|
|
- Audio thread owns the active processing plan and DSP state.
|
||
|
|
- Backend callbacks follow the backend's documented threading contract.
|
||
|
|
|
||
|
|
Do not free an active plan until the audio thread has released it. Pick and
|
||
|
|
document a bounded handoff/reclamation strategy before real-time graph swaps.
|