This is interesting. Recently, I added a time stamp. In a section, it is only supposed to go to 00:12:36:04. But when I export and watch the video, it is at least 00:12:36:06. There is a difference of :02! And after that, there is a frame or two of a video clip (without filters) that should not be there. Does this help solve the issue?
(To clarify, the previous clip keeps playing, but now with no filters.)
Moreover, as the left eyeball lingers in another scene for a few frames, and it is controlled by the filter “V3” (the bottom one of the two layers being used for that clip), we can gather that V3 is lagging by some fractions of a second, even though in the shotcut GUI it says it isn’t. Why is this happening?
So all of this revolves around the video layers (V4, V3, V2, V14) being consistently desynched by a few frames. Any ideas how to solve this?
From your MLT file, the <profile> (Video Mode in Shotcut) says frame_rate_num="65868750" frame_rate_den="2195909" (~29.996120057798387820260311333484). You will see that the time values in the XML are in the format HH:MM:SS.ms to make them adjust for frame rate changes (in Export or changing Video Mode). Quite likely, the conversions between these time values and the frame rate of source clips to that project frame rate is experiencing rounding or truncation errors. You can probably avoid this by using a better project frame rate by opening the project, choosing a particular Video Mode whose fps matches the majority of your clips (hopefully they are not this wonky rate), and then reviewing everything.