Repeated frames in videos

Hi, I was browsing the videos and it seems there are quite a few repeated frames.
e.g. taking a random video from the training set, 00WK7DR6FyPZ5u3A.mp4 appears to repeat every 6th frame.
I checked this on the CVision annotation tool linked from the instructions.
Any idea what the underlying issue behind that is? I’d like to understand whether the repeated frame corresponds to 1,2,3,3,5,6, where frame 4 is skipped entirely but time is preserved, or to 1,2,3,3,4,5…, where the true timing of the sequence is broken but frame 4 is shown. I suspect the former?

Hi fishysisi,

It is 1,2,3,3,5,6. This is an artifact of the encoding process and how skipped frames were handled when re-encoding so they were clean enough to play in most video players. Due to time constraints it was not possible to re-encode the videos with duplicate frames removed and timing preserved. Please let me know if you have any further questions on this subject.