i3rs

An open-source, cross-platform alternative to MoTeC i2 Pro for motorsport telemetry analysis. Built entirely in Rust.

i3rs opens MoTeC .ld log files and provides time-series graphs, lap navigation, multi-panel workspaces, and cursor-synchronized analysis -- all in a single native binary with no runtime dependencies.

Features

• MoTeC .ld/.ldx parsing -- reads the binary log format produced by MoTeC M1 ECUs, including channel metadata, sample data, and lap timing from .ldx sidecar files
• Memory-mapped file access -- opens 100MB+ files instantly via memmap2; channel data is decoded on demand
• Min-max decimation -- renders 200+ channels at 60fps by downsampling to pixel resolution while preserving visual peaks and valleys
• Multi-channel graphs -- overlay or tiled modes, dual Y-axes, color-coded lines, drag-and-drop channels
• Lap detection & navigation -- parses lap boundaries from data or .ldx files, lap markers on the timeline, click-to-zoom
• Dockable panel layout -- multiple graph panels, channel browser, cursor readout, and timeline overview in a resizable tabbed workspace
• Cross-panel synchronization -- cursor position and zoom range stay in sync across all panels
• Workspace + project persistence -- save reusable race-weekend project files with session lists, math channels, overlays, and worksheet layouts
• Global channel preferences -- reuse preferred colors and display units across sessions and projects
• Session comparison + themes -- inspect session metadata side by side and switch between light, dark, and high-contrast themes
• Cross-platform -- runs on macOS, Windows, and Linux via wgpu backends (Vulkan/Metal/DX12/OpenGL)
• Packaging scaffold -- repository-managed cargo-packager config for macOS .dmg, Linux .AppImage, and Windows .msi builds

Building

Requires Rust 2024 edition (rustc 1.85+).

cargo build --release

Packaging

i3rs now includes a checked-in cargo-packager configuration for release artifacts.

cargo install cargo-packager --locked
cd crates/i3rs-app
cargo packager --release --formats appimage

Use platform-native formats on each OS:

• macOS: cargo packager --release --formats app dmg
• Linux: cargo packager --release --formats appimage
• Windows: cargo packager --release --formats wix

More detail is in docs/packaging.md.

Releasing

PRs are verified in GitHub Actions with linting, tests, a crates.io dry run for i3rs-core, and cross-platform builds. PRs also verify that the web/wasm bundle builds successfully with Trunk. Pushes to main are scaffolded to publish i3rs-core and i3rs-cli to crates.io when the workspace version is new, and separately package desktop/web artifacts into a GitHub release when the app package version in crates/i3rs-app/Packager.toml is new.

Release details and required secrets are documented in docs/releasing.md.

Usage

GUI Application

# Open with file picker
cargo run --release -p i3rs-app

# Open a specific file
cargo run --release -p i3rs-app -- path/to/session.ld

You can also drag and drop .ld files onto the application window.

Use File > Save Project... to capture the current worksheet layout, math channels, and referenced .ld sessions into a reusable .i3rsproj file. Use View > Session Details to compare the current run against another project session, and right-click plotted channels to save global color/unit defaults.

Web / Wasm

Build the web bundle with Trunk:

rustup target add wasm32-unknown-unknown
cargo install trunk --locked
cd crates/i3rs-app
trunk build --release

The generated bundle is written to crates/i3rs-app/dist/. The release workflow also publishes this bundle as a GitHub release asset named i3rs-web.tar.gz.

CLI

Print the legacy text summary for a log file:

cargo run --release -p i3rs-cli -- path/to/session.ld

When installed, the executable is named i3rs; the examples below use cargo run for source-tree development.

The CLI also exposes machine-readable commands for agentic/session analysis:

# Session metadata, channels, and lap windows
cargo run --release -p i3rs-cli -- summary path/to/session.ld --format json
cargo run --release -p i3rs-cli -- channels path/to/session.ld --filter speed --format json
cargo run --release -p i3rs-cli -- laps path/to/session.ld --format json

# Extract how values change through a lap instead of relying only on min/max
cargo run --release -p i3rs-cli -- extract path/to/session.ld \
  --channel "Engine Speed" --channel "Throttle Position" \
  --lap "Lap 1" --x lap-percent --resample points:200 --format csv

# Per-lap statistics and lap-to-lap comparison
cargo run --release -p i3rs-cli -- stats path/to/session.ld \
  --channel "Engine Speed" --group lap --format json
cargo run --release -p i3rs-cli -- compare-laps path/to/session.ld \
  --channel "Engine Speed" --laps "Lap 1,Lap 2" \
  --reference "Lap 1" --x lap-percent --resample points:200 --format json

See docs/cli-analysis.md for command output shapes and the repeatable run spec format.

Show CLI help or install agent skill files for the CLI:

cargo run --release -p i3rs-cli -- help
cargo run --release -p i3rs-cli -- install-skill

install-skill writes $CWD/.agents/skills/i3rs/SKILL.md and $CWD/.claude/skills/i3rs/SKILL.md.

Project Structure

crates/
  i3rs-core/    Core library: .ld/.ldx parsing, data model, lap detection, downsampling
  i3rs-app/     Desktop GUI application (egui + egui-dock)
  i3rs-cli/     Command-line file inspector
docs/
  PLAN.md           Development roadmap (Milestones 1-9)
  cli-analysis.md   Machine-readable CLI command reference
  ld-file-format.md MoTeC .ld binary format specification
test_data/
  VIR_LAP.ld        Sample telemetry log (~4.8MB, single lap at Virginia International Raceway)
  VIR_LAP.ldx       Associated lap metadata (XML sidecar)

Key Dependencies

Crate	Purpose
memmap2	Zero-copy memory-mapped file access
half	IEEE 754 float16 decoding
eframe / egui	Immediate-mode GUI framework
egui_plot	Line chart rendering with pan/zoom
egui-dock	Dockable, tabbable panel layout
quick-xml	.ldx sidecar XML parsing
rfd	Native file open dialogs

Test Data

The test_data/ directory contains a small sample dataset for development and testing:

• VIR_LAP.ld -- a single-lap telemetry recording from Virginia International Raceway (~4.8MB)
• VIR_LAP.ldx -- the accompanying XML sidecar with lap timing data

These files are produced by a MoTeC M1 ECU and exercise the full parsing pipeline: header, event/venue/vehicle metadata, channel metadata linked list, and multi-type sample data.

Roadmap

See docs/PLAN.md for the initial roadmap.

License

MIT