As the developer of VidSync I have never personally used the one other piece of software that does some of the same things in fish measurement, SeaGIS EventMeasure and the related suite of applications. It has been around longer than VidSync, which has been around for 15 years. As best I can tell from their documentation, I think VidSync is much more full-featured (especially in the variety of playback controls and ways to organize and annotate measurements), but I’m obviously biased and I welcome readers to study both tools and make up their own minds on that.
One obvious distinction between the systems is Mac (VidSync) vs Windows (EventMeasure). Another is the price of the systems themselves. EventMeasure costs thousands of dollars for the software and thousands more for the calibration hardware. VidSync is free, and you can build the calibration hardware yourself for a couple hundred dollars at a sign printer and hardware store.
Although they use very different mathematical methods, both systems have independently reported similar, high precision and accuracy in internal tests by their own developers. I’m writing this post to call attention to an interesting study that came out this year (which I wasn’t aware of until after publication) comparing the accuracy of the two systems on equal footing. In short, they found both systems have similar, high precision and accuracy. You can see the study at:
López-Macías, J., Bravo-Ormaza, E., Chinacalle-Martínez, N. et al. Comparison of Two Stereo-Video Software for the Assessment of Marine Resources. Thalassas 39, 395–404 (2023). https://doi.org/10.1007/s41208-022-00507-4