Thank you Alister, I better see now. In fact, after some observations, it seems that it cuts sometimes some images before my Mark In point or after the Mark Out point, I suspect it cuts where it detects the nearest I-Frame to complete an entire Long GOP. It that case, it probably doesn't re-encode a...

hi, I usually Mark In (I) and Mark Out (O) all my clips to choose the good part in it (more clean and remove extra lenght) and then I create New clip using In/Out selection and after that I delete the original. As this is a really fast step, I suppose there is NO re-encoding but only shortening ? I ...