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Overview of enhanced video analysis - Syncing video and Protern data

Video analysis is critical for athlete development. Adding sensor data to video makes the process more objective and easier to understand for the athlete.

What's in this article

This article includes a broad overview on enhanced video analysis. In particular, it covers the following:

  1. What is automatic and manual syncing
  2. Pros and cons of different video angles
  3. Types of data to display on video

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.

 


Automatic and manual video syncing - What is it?

Automatic syncing

Automatic syncing is when the video software (e.g. Dartfish or Telemetry Overlay) can automatically link each video frame with data recorded from Protern.

  • Pros: Fast, simple and extremely accurate syncing of video to data
  • Cons: Requires the video to have an accurate Universal Coordinated Time (UTC) timecode.

All that is required is the full Protern session and time coded video. The video software will automatically determine what data to include in the video for a fast and accurate sync.

There three ways to get UTC time coded video:

  1. GPS enabled action camera
    Some action cameras use their onboard GPS to embed this time (e.g. GoPros), but most cameras, including phones, do not. 
  2. Dish time code device
    Dish is a device that gets an extremely accurate UTC time code from the GPS satellite network. It converts the time into an audio signal called Liner TimeCode (LTC) that can embedded in the video via the camera's microphone port. The video software can read the audio time code and sync the video with the Protern data.
  3. Protern Clock: LTC Generator iOS app
    Similar to the Dish device, the Protern Clock: LTC Generator app generates an audio UTC time code. Instead of a dedicated device, the app runs on an iPhone or iPad. The iOS device needs to be plugged into the microphone port of the camera.

Manual Syncing

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.

 


Pros and cons of different video angles

Follow cam

A follow cam is when the coach follows behind the athlete with a camera. Generally a small and light camera like a phone or GoPro is used. 

Syncing with Protern data

  • Automatic syncing: GoPros record UTC time if they have a GPS satellite lock and can be used for automatic syncing.
  • Manual syncing: Phones do not record UTC time, so manual syncing would be required.

Pros and cons

  • Pro: The rear view is easier for the athlete to understand the movements they are doing
  • Con: Time consuming for the coach as you can only film one athlete at a time before having to go back up the hill.

Static cam

A static camera is a camera located in one place on the hill. This could be on a tripod, or a coach standing on the side of the course. Dedicated cameras with a high optical zoom are often used.

Syncing with Protern data

  • Automatic syncing: Cameras with a microphone port can use the Protern LTC Clock iOS app or Dish to add an audio UTC time code
  • Manual syncing: Cameras without a microphone port can still be used to sync with Protern data.

Pros and cons

  • Pros: High-zoom, high resolution cameras can be used; Easy to capture all the athletes
  • Cons: Can sometimes be difficult to see angles of skier correctly

Point of View (POV)

POV is useful in SkiCross as one athlete's camera can act as a follow cam for the other athletes to see line choice.  A helmet mounted 360° type camera is ideal to ensure all the angles and action is covered regardless of the position of the athlete.

Syncing with Protern data

  • Automatic syncing: Many 360° include a GPS chip and can record UTC time for automatic syncing. Check with your video program to make sure it can support your camera.

Pros and cons

  • Pros: 360° need some processing to get the right angles at the right time
  • Cons: Extra step is required to process the video before it can be synced with Protern data

Drone

Drones are used rarely, as most mountains do not allow them on the hill. They can be used as a fast follow cam (i.e. they can fly back up to capture the next athlete), however the high angle is less useful for feedback.

Syncing with Protern data

  • Automatic syncing: Many drone cameras include a GPS chip and can record UTC time for automatic syncing. Check with your video program to make sure it can support your camera.

Pros and cons

  • Pros: Capture some interesting views; Great for social media!
  • Cons: Probably not allowed at your mountain

 


Types of data to display on video

Speed

Speed is the most common metric displayed on the video. The value can be shown as a graph or a speedometer. For either view, it is helpful to compare two videos to see the actual speed difference in different sections.

Acceleration

Acceleration data shows how much the skier speeds up and slows down during the run. This, paired with speed, gives the athlete an objective measurement of the impact of a tactic or technique. 

Kristoffersen speed data

Turn details

Protern can generate a number of turn related metrics, including average g-force, energy dissipation, and entry and exit speed among others. This level of video integration can helpful for more in-depth analysis sessions rather than everyday analysis. 

Turn Analysis - GS