Syncing Your GPX Overlay with Video Footage
Accurate synchronization is key to making your data overlays meaningful. GpxOverlay provides flexible methods to ensure your speed gauge, map position, heart rate, and other widgets perfectly match the action happening in your video.
Why Sync?
GPS data (GPX) and video are recorded separately. Slight time differences or starting/stopping recordings at different moments mean the data needs to be aligned with the visual footage. Proper syncing ensures that when you see a sprint on video, the speed gauge shows the corresponding high speed, or when you pass a landmark, the map overlay shows the correct position.
Synchronization Methods in GpxOverlay:
1. Manual Time Selection / Time Offset
This method involves finding a specific, easily identifiable moment in both your GPX data (e.g., the start of a climb, reaching a peak speed) and your video footage (e.g., passing a specific sign, starting an effort). You then tell GpxOverlay the timestamp of that event in your GPX data. GpxOverlay uses this reference point to align the rest of the data. You might also apply a time offset if you know the exact difference (e.g., "GPX started 5 seconds before video").
- Pros: Doesn't require video upload to GpxOverlay. Can be precise if you have a clear reference point.
- Cons: Can be time-consuming to find the exact matching moment. Relies on accurate time identification.
2. Video-Based Synchronization
Upload your video file directly to GpxOverlay. The tool will display the video alongside a representation of your GPX data (like the map or elevation profile). You can then visually scrub through the video and the data simultaneously to find the perfect alignment point. Click to set the synchronization, and GpxOverlay handles the offset calculation.
- Pros: Often faster and more intuitive. Visual confirmation makes alignment easier.
- Cons: Requires uploading your video file.
Tips for Accurate Syncing:
- Choose a clear, distinct event for manual syncing (e.g., starting watch/camera simultaneously, passing a unique landmark, a sudden stop/start).
- Use the preview function extensively to check alignment before generating the final overlay.
- Small misalignments can be noticeable, so take the time to get it right!
By correctly syncing your data, you ensure your GpxOverlay widgets accurately reflect the performance and journey captured in your video.