Masking problems

I have a piece of footage that I filmed in front of a green screen using a model of the millennium falcon with the camera zooming out. Now to make the model appear as if the model is flying towards the camera, I have reversed the footage using one of the temporal tools. I have masked out the area around the green screen. However, as soon as I have adjusted the size at different points I watch back what I have done and it does something weird. The playback shows the masking frame, with the green keyed out; however, outside of the masking frame I can see what the mask is supposed to get rid of. This doesn’t happen if I turn off the reverse function.
Any help please. I’ve updated my graphics drivers and it's still happening.


  • Jernau
    Jernau Posts: 71
    edited December 2011
    You may have discovered a bug (or perhaps "feature" is a better word) in HitFilm.
    I managed to replicate your findings by applying a 'Time Reverse' effect and then keyframing the Mask Path on the same layer. The Mask shape in the Viewer didn't match up with how the Mask was being applied to the footage.
    I'm pretty sure what's happening is that the Mask is being applied to the footage in forward time, even though the footage has been reversed. (This means that if you keyframe the Mask Path for the "first" frame, it will actually be applied to the "last" frame.)
    The work-around is to keyframe the Mask Path before you apply the 'Time Reverse' effect.
    I'll leave it to the HitFilm team to say if this is something they can fix or not.
  • SimonKJones
    SimonKJones Posts: 4,448 Enthusiast
    Masks are applied before effects, so this will indeed be masking the effect *before* the time reverse. If you want to mask the reverse/retimed clip, you should make it an embedded comp.