GyLog Sync Direct (v2.1.6-beta)

GyLog Sync Direct is an open-source macOS tool by NagiLab for filmmakers and video creators using external gyro logs with Gyroflow and DaVinci Resolve.

NagiLab builds creator-led tools for video, photography, AI media, and practical creative production workflows.

End-to-end macOS utility for processing mirrorless footage together with GyLog gyro logs, producing ready-to-use .gyroflow projects that load directly into the Gyroflow OFX plugin for DaVinci Resolve — with no manual sync, no lens profile loading, and no Gyroflow Desktop step required.

This tool is part of the GyLog ecosystem by NagiLab. Legal and App Store distribution may be handled by Kumo, Inc. where required.

What it does

For each video clip in your batch, GyLog Sync Direct:

1. Slices the master .gcsv to the clip's time range
2. Auto-detects mount tilt (install_angle) from the gcsv header and writes it to gyro_source.rotation
3. Applies the IMU axis remap based on the Phone connector side selector (USB-C/Lightning right → ZYx, left → zYX)
4. Embeds the optical-flow sync offset (median of 5 sync points, outliers >500ms rejected, then applied uniformly across the clip for drift-free correction on long takes)
5. Optionally embeds your lens profile's calibration_data so DaVinci OFX applies lens distortion correction automatically
6. Optionally overrides the rolling-shutter frame_readout_time with a value you supply (e.g. from horshack-dpreview's RS database)
7. Exports a per-clip .gyroflow project file ready for OFX consumption
8. Writes a per-folder CSV processing report so you have a record of what was processed with what settings

Recent changes in v2.1.6-beta

• Fixed camera timestamp handling when QuickTime metadata is interpreted with the wrong timezone.
• Improved Magic Lantern / Canon EOS M workflows by using paired MLV file timestamps when MOV creation time is missing.
• Improved folder drops that contain MLV files by automatically finding matching MOV files.
• Updated the signed and notarized macOS build metadata to v2.1.6-beta.

Workflow

1. Drop mirrorless clips + master GCSV (+ optional lens profile) into the app, set Phone connector side and (optional) Rolling Shutter value, hit Sync
2. Each clip gets a paired {name}.gcsv (sliced) and {name}.gyroflow project; if RS override was set, the file is named {name}_RS{value}ms.gyroflow so multiple RS attempts can coexist
3. Drop the video clip into a DaVinci Resolve timeline, apply the Gyroflow OFX plugin on the Color page — it auto-loads the matching .gyroflow from the same folder and applies stabilization
4. Adjust FOV / smoothness in OFX as needed and export

First time? See the full step-by-step TUTORIAL for mount setup, lens profile creation, rolling-shutter tuning, and DaVinci usage.

Advanced Options

• Camera Clock Drift (sec) — manual offset if your camera and phone clocks weren't synced at shoot time (rare, ≤2-minute clips rarely need this)
• Sync search range (ms) — how far the optical-flow sync looks for the true offset; default 5000ms
• Phone connector side — Right (USB-C/Lightning on right of camera, the default Xperia mount) or Left
• IMU orientation override (advanced) — force a specific 3-letter axis code (e.g. ZYx, XyZ) for unusual mounts (vertical phone, upside-down, screen-down, etc.). Find the right value with Gyroflow Desktop's Auto-detect IMU orientation on one clip
• Rolling Shutter (ms) — manual frame_readout_time override. Look up your camera at horshack-dpreview's RS DB or measure empirically with Gyroflow Desktop's Frame Readout Time slider
• Lens profile — file picker for a Gyroflow lens profile JSON. When set, embedded as calibration_data so DaVinci applies lens correction without a manual "Load lens profile" step

Mount orientation

The IMU axis remap defaults to:

• Right (default) → ZYx — verified for Sony Xperia / similar Android phone with USB-C on the right of the camera and screen up
• Left → zYX — phone flipped 180° around its long axis (USB-C on the left)

Mount tilt (forward/back pitch, left/right roll) is automatically captured by GyLog's Calibrate Mount feature and embedded as install_angle:R{roll}_P{pitch} in the gcsv header. The full Euler range is supported: flat-on-top (~0°), tilted forward (e.g. -52° in the standard A7R II + Xperia rig), or even vertical (~±90°).

For unusual mounts (vertical phone parallel to the camera back, upside-down, etc.), use the IMU orientation override field.

iPhone-on-mirrorless rigs (with install_angle from Calibrate Mount) share the same Right/Left selector as Android. iPhone standalone (no install_angle, recording with the iPhone's own camera) is detected automatically and uses XYZ (IMU axes match camera axes on the same device).

Companion apps

• GyLog for iOS — iPhone IMU logger and standalone gyro recorder (App Store)
• GyLog for Android — Android IMU logger, primary companion for mirrorless rigs (Play Store release in progress)

Requirements

• macOS 13 (Ventura) or later
• Apple Silicon (Rust bridge built for arm64)
• DaVinci Resolve with the Gyroflow OFX plugin for the final stabilization

Building from source

# Install Rust + librsvg (for app icon generation):
brew install rust librsvg

# Build the Rust bridge + Swift app:
bash build_app.sh

# Build only (skip code signing + notarization, for development):
SKIP_SIGN=1 bash build_app.sh

The Rust bridge requires a one-time cargo build of gyroflow-core which pulls in OpenCV and FFmpeg (~10 minutes on first build).

License

Licensed under the GNU General Public License v3.0 — see LICENSE.

This project incorporates gyroflow-core from the Gyroflow project (© 2021–present AdrianEddy and contributors, GPL-3.0). Any binary distribution of this tool must make the corresponding source code available under the same license — this GitHub repository fulfills that obligation.

Acknowledgements

• Gyroflow — the stabilization engine this tool wraps (GPL-3.0). Please consider supporting Gyroflow if you find this workflow valuable.
• OpenCV — optical flow analysis (Apache-2.0)
• Arm KleidiCV — ARM-optimized image primitives (Apache-2.0)
• Intel oneTBB — parallelism framework (Apache-2.0)
• horshack-dpreview Rolling Shutter Database — community reference for camera RS timing

Full dependency list with copyright and license details: THIRD_PARTY_LICENSES.md

Reporting bugs

Open a GitHub issue with:

• macOS version + Mac model

• Camera + phone model + mount orientation

• A short clip + gcsv that reproduces the issue (if file size allows)

• The CSV processing report (GyLogDirect_*.csv) generated next to the clips

  Maintainer workflow

This project is maintained as a creator-led open-source tool.

NagiLab plans to use AI-assisted development tools, including Codex, to improve code review, issue triage, documentation, testing, release preparation, and long-term maintenance.

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