I have just encountered this problem that has baffled me and my colleagues. But I know you clever people will put us straight right away!!
I have rendered out 11 mp4 files from my project to make editing easier when changes are requested. I did this because my original rendering for the whole project took 22hrs and I can't afford to do that every time a little change is made. The original mp4 file is 40 mins long.
So I now have these rendered mp4 files and when I put them all back together, all seemed ok... except that the full length of the project was now 3 mins short!! I narrowed this down to one particular mp4 file. Remember all of these mp4 files are from the same project with same settings!! I noticed that the mp4 file was just 31 seconds long. So I rendered it out again. The mp4 file on my machine is perfect. 3m 20s long and the settings are all exactly the same as all other mp4 files I have rendered out.
Yet a simple drag and drop or an import into AE and the file is showing as 31 seconds long! I even have the pre-comp open in another instance and it clearly shows it as 3m 20s long.
I have attached an image to hopefully explain what I mean and hope someone can throw some light on it. Makes no sense at all to me, but sure it will to you clever lot.
exact render settings? Work Area? Markers? Audio? SOurce timecode? There could be any number of reasons, though I agree that it's extremely baffling And disconcerting.
Thanks for the reply. But as I said, the settings are exactly the same as all other mp4 files that were fine.