One of the main challenges of merging data streams with videos is to get a precise synchronization between the data and the video. In some cases, it is possible to link a data point to a precise event in the video (e.g. a swimmer diving at the start of the 100m freestyle). However, in many other situations there is no obvious event on the video and the data stream that you can use as synchronization point. Think about long distance running or cycling for instance, where you may get a data stream of 1+ hour and you want to synchonize it with a 5 minutes video that happens in the middle of the route.


Dartfish offers two ways to synchronize video and data at any point with a precision of more than 1/10th of a second: QR Code and Linear Timecode

  • With the QR Code synchronization, at the end of each video recording the coach has to film a mobile device on which an app displays a QR Code that indicates the time. Dartfish software can then extract the time from this QR Code and use it to synchronize the imported data streams
  • The Linear Timecode (LTC) leads to the same result but with a different process. The coach connects an audio source to his camera. This audio source can be a small box or even a mobile phone running an app. This audio is then recorded in the video and can be interpreted as a time data stream by Dartfish


QR Code Synchronization

LTC Synchronization


QR Code Synchronization

Film a QR code displayed on a mobile app during your training session



Requirements

  • myDartfish Pro or myDartfish Pro S
  • Genlock Android app
  • Android mobile device
  • CSV data stream from a sensor meeting the specific format (see below)


Install the Genlock app


During the training

  • Set up the sensor as usual
  • Place the mobile device next to you and start Genlock
  • Capture the video with your camera
  • Film the QR Code for 5s and stop the recording. Make sure the image is not blurry and the camera is stable whn capturing the QR code

After the training

  • Open the csv file from the sensor and make sure that the following points are valild
    • The first column is the time
    • Time format is YYYYMMDDHHMMSSCCC (example: 20190116T121955700)
    • Column delimiter is ","
  • Launch Dartfish software
  • Go to Edit and add the video to the montage
  • Import the data stream from the csv file
  • Pause the video when the QR Code is visible
Tip: for an ideal synchronization, make sure to pause the video with 1-2s of QR Code visible before and after the playhead


  • Click on Detect Synchronization

  • Click on Detect Synchronization
  • Select QR-Code detection
  • Close the window and click on Reset Synchronization

The data stream is now accurately synchronized to the video


LTC Synchronization

Connect an LTC audio source to the camera during recording


LTC setup with the ProTern app


Requirements


During the training

  • Set up the sensor as usual
  • Connect the LTC generator to your camera
    • DISH DM: connect the box to your camera with an audio jack cable
    • Protern Clock LTC Generator: launch the app and connect your mobile phone audio output to your camera audio input
  • Capture the video with your camera

After the training

  • Open the csv file from the sensor and make sure that the following points are valild
    • The first column is the time
    • Time format is YYYYMMDDHHMMSSCCC (example: 20190116T121955700)
    • Column delimiter is ","
  • Launch Dartfish software
  • Go to Edit and add the video to the montage
  • Import the data stream from the csv fil
  • Click on Detect Synchronization

  • Click on "Detect Synchronization"
  • Select Linear Time Code
  • Close the window and click on Reset Synchronization

The data stream is now accurately synchronized to the video