Video analysis is critical for athlete development. There are two ways to add sensor data to video, manually or automatic. Adding sensor data to video makes the process more objective and easier to understand for the athlete.
This article goes over the differences, as well as pros and cons, of manual and automatic syncing of video to data.
Syncing data to video is required to ensure your speed, acceleration and time data is lined up correctly with the video. Video and data that is out of sync by even 0.2s would result in turn data being displayed after the critical point in the turn.
This article goes over the following:
What is enhanced video analysis?
Enhanced video analysis is involves the marrying of objective data with video. Combining both data and video gives athletes and coaches a clearer understanding of what is happening and its impact on speed, acceleration and other metrics.
Difference between automatic and manual video syncing
|Manual Video-Data Syncing||Automatic Video-Data Syncing|
|Description||Manually lining up the start of the CSV data with a known point in the video, such as a gate or terrain feature.||Video software can automatically line up the CSV data with the start of the video by reading an LTC (Linear Timecode) audio signal, or embedded GPS timecode.|
|Accuracy||Variable, but possible to be accurate to 0.1s||Exact to 0.03s for 30fps, up to 0.01s for 120fps|
|Time to produce each video (not including rendering)||5-10 minutes for the first video, 1-2min per video||30 seconds for the all videos|
|Camera Requirements||None||Camera with a microphone port and LTC generator, or GPS enabled action camera|
|Data Requirements||Quantriq must start at known physical point that the camera can see.||None|
Automatic syncing is when the video software (e.g. Dartfish or Telemetry Overlay) can automatically link a video with data recorded from Protern.
- Pros: Fast, simple and extremely accurate syncing of video to data
- Cons: Requires the video to have an LTC timecode (Linear timecode), or a GPS enabled action camera like a GoPro, DJI, or Insta360
What is LTC?
LTC, or Linear Timecode, is an audio timecode that certain software can decode to understand exactly when each frame of the video was recorded. It was developed over 40 years ago for the Film and Television industry. In order to link video with GPS timecoded data (i.e. Protern data), the LTC needs to record Universal Coordinated Time and date (UTC). Click here for more information on LTC Generators that work with Protern.
To automatically sync the video and data, all that is required is Protern data (full session or Quantriq runs) and timecoded video. The video software will automatically determine what data to include in the video for a fast and accurate sync.
There two ways to get video that can be automatically synced:
- GPS enabled action camera
Many action cameras, such as GoPro, DJI and Insta360, use their onboard GPS to embed a UTC time that software like Telemetry Overlay can decode. Note, that phones and standard cameras with GPS do not record a GPS timecode in the video.
- Video camera with a microphone port and an LTC Generator
If your video camera has a microphone port, then you can use an LTC Generator to record an audio timecode. There are two LTC Generator options:
- Dish timecode device
Dish is a device that inserts the LTC timecode via the microphone input of your camera. The timecode comes from a GPS sensor built into the device. The Dish can be mounted on the hot shoe attachment of your camera. Having a dedicated piece of hardware to generate the LTC timecode is helpful for large teams, or those who are regularly doing enhanced video analysis.
- Protern Clock iOS app
Protern Clock: LTC Generator iOS app inserts an LTC timecode via the microphone input on your camera. You will need a 3.5mm audio cable, and possibly an adapter for your iPhone or iPad, to connect to your camera's microphone input. The app gets its time from highly accurate Internet connected time servers located around the world.
- Dish timecode device
Manual syncing of video and Protern data involves lining up the video with the start of the Protern data.
- Pros: Possible to sync data with almost any video without any preparation or special equipment (UTC time code in the video).
- Cons: Syncing can be less accurate than the automatic method and is more time consuming
While this process is more time consuming and less accurate, it can be useful if you do not own a camera with a microphone port or can use a GoPro.
Learn more: How to manually sync Protern data with video.