.mov has alpha channel - how to key out background?

AllanFinney
AllanFinney Website User Posts: 7

Hi - I've been looking in the manual and on the forums but can't figure out how to do this so it may be a pretty basic question - how do I replace a background from a .mov clip that says it has an "alpha" channel? The clip was downloaded here - https://www.videvo.net/video/dna-strand-rotate-loop-with-alpha-matte/1658/  Any help would be greatly appreciated!

Comments

  • FilmSensei
    FilmSensei Moderator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,067 Ambassador

    @AllanFinney

    I downloaded the video and took a look at it. It is a 30 second clip where the first 15 seconds is the video and the second 15 seconds is the alpha matte. You will want to put the clip into a 15 second composite shot. Drag and drop the clip in twice. On the bottom clip drag it to the left so that the alpha matte matches the regular video. You may need to turn down the opacity of the top clip to see them both. After they are lined up, hide the alpha matte clip and reset the opacity of the regular video. Drag the Set Matte Effect onto the regular video and source the alpha matte. Change the matte source to Luminance. That's it!

    If you really have trouble, I would be happy to make a quick video walking through the step for you.

  • Triem23
    Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 19,833 Ambassador

    To expand on what @FilmSensei writes.

    Change the Matte Source to Luminance and the Blend Mode to Replace. (Jay, did you leave the Blend in Add? Did that work?)

     

  • FilmSensei
    FilmSensei Moderator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,067 Ambassador

    @Triem23 I left the Blend Mode at Normal. It worked just fine.

  • AllanFinney
    AllanFinney Website User Posts: 7

    All right - Thanks - that's it! I would have never figured this out so thanks for taking the time! Much appreciated.

  • FilmSensei
    FilmSensei Moderator, Website User, Ambassador, HitFilm Beta Tester Posts: 3,067 Ambassador

    @AllanFinney

    Awesome! If you need anything else, please don't hesitate to ask.

  • Triem23
    Triem23 Moderator Moderator, Website User, Ambassador, Imerge Beta Tester, HitFilm Beta Tester Posts: 19,833 Ambassador

    Allan I suggest you get comfortable with the Set Matte effects and it's options. Set Matte will be the key to a lot of other things you may want to do. As one example, want to fill text with video? That's Set Matte.