New Video Sync Unit

Benedikt, October 13 2021

With our new video synchronization unit, you can now also automatically synchronize videos recorded with your smartphone or tablet camera. As with our old sync unit, through the microphone-in audio jack. For professional cameras or analogue systems, we provide a version with a BNC connector.

Picture of the video synchronization unit connected to a smartphone

A brief attempt to explain our video synchronization

How are we able to provide an effortless and precise synchronization of any videos with our sensor data? This is a mystery for most people and there are - to our knowledge - only two other companies on this planet who are able to do this for non-specialist users. One of these companies, Dish.TC, has become our preferred provider for our new synchronization unit.

So what's the trick?

GPS. This system can not only provide your location but provides also one of the world's most precise clocks (with a time accuracy of ≤ 30 nanoseconds!). The sensor worn by the athlete has a GNSS receiver and records therefore also the GPS time. Thus, we know exactly when each sample has been measured on our sensor.

The sync unit has a GPS receiver as well. It therefore measures the exact same time as the sensor on the athlete. Even though they are completely independent and never need to be together. The sensor on the athlete is not aware that there is a sync unit and the sync unit is not aware that there are other sensors around.

The trick of the sync unit is now to convert the GPS time in some form that can be recorded by a video camera. The video camera can record two things: images and sound. There are image-based solutions that require to film a constantly changing QR-code at the beginning of each video. Which is not very practical for in-field measurements and also not really precise. The sound-based solution is much better: cameras are made to store the sound they record perfectly synchronized with the images. So, all we need to do is to generate a sound that encodes the time and send this sound to the camera.

Use standards from the 1960s

To encode the time on the sound we can use some self-made encoding scheme as we did for our first-generation sync unit. Or one can be smart, not re-invent the wheel, and use a standard from the film industry from the 1960s: Linear Timecodes (LTC). This is what Dish.TC did. So they became our preferred provider of our new video synchronization units.

Remains the question on how to send the sound to the camera. We could do it with a loudspeaker. But then everyone would go crazy after seconds (did you know that the LTC sound has been used as a sound effect for science fiction movies?). Thus, the only other way is to use the microphone-in line, which most of today's mid- and high-end cameras have.

A picture is better than 1000 words...

Yes, there is quite some science working behind the scenes. Fortunately, all automatized and invisible to you, dear user. What you need to know is how easy it is to use our video synchronization. For this, we have prepared three short videos.

Step 1: Connect the sync unit to the camera

Switch on the sync unit somewhere outdoors and wait 20 minutes. With a standard audio cable, connect the sync unit with the microphone-in connection of your camera.

Step 2: Record your athlete

Record any number of videos of your athletes. The video duration should be at least 5 seconds and we recommend to keep your videos below 30 seconds. Besides this, you can record the videos however you want. For illustration purposes we just recorded a video with a few short and fast movements of the sensor.

Step 3: Upload and view your videos

Upload the data and video to our webapp. This is so simple and boring that we do not even think of making a video of this. But of course, you would like to see how this video with the speed data overlay looks like. In the example below we play the video at 20% speed slow-motion.

You want to use it yourself?

Contact us. The sync units are available now and can be shipped immediately. Don't wait until it is too late and all your competitors are improving their performance way faster because of the time they save with our objective video analysis.