bobfromsaint pete beach

Q: Modifying Alpha Channel in Motion 5

I have used chroma key successfully in many video projects in Motion 5, however I am now interested in modifying and in some cases, removing an alpha channel from an imported clip. I have read the Users Manual and learned about exporting the video using Apple ProRes 4444 and ensuring the menu dropdown choice option include color or color and alpha, however I believe my question comes before exporting.

 

I have purchased video clips for use in my projects with alpha channels removed and would like to explore using that kind of editing feature myself.

 

Am I just exercising wishful thinking here or is removing alpha channel data possible within the Motion 5 editor no matter where I export the video?

 

Thanks for any assistance for a novice-to-medium-level-skilled editor.

 

Bob T. an editor in the making ...

iMac, OS X El Capitan (10.11.5)

Posted on May 21, 2016 7:35 AM

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Q: Modifying Alpha Channel in Motion 5

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  • by Karsten Schlüter,

    Karsten Schlüter Karsten Schlüter May 21, 2016 8:15 AM in response to bobfromsaint pete beach
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    May 21, 2016 8:15 AM in response to bobfromsaint pete beach

    well, ... no alpha means..? something, some content, e.g. a solid color

     

    and this is defined in the Project Properties, look:

     

    Bildschirmfoto 2016-05-21 um 17.04.36.png

     

    both settings look in canvas same: black.

     

    but when you export with the setting on the right, instead of an alpha=transparency, the selected color fills the background.

     

    is that what you're looking for?

  • by bobfromsaint pete beach,

    bobfromsaint pete beach bobfromsaint pete beach May 21, 2016 8:23 AM in response to Karsten Schlüter
    Level 1 (4 points)
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    May 21, 2016 8:23 AM in response to Karsten Schlüter

    No. My setting is always on "Transparent." I need to do what you see in this clip screen capture (windows are transparent) to another clip - a partial alpha channel removal for parts of the clip

     

    Car and Driver No Alpha.jpg

  • by Karsten Schlüter,

    Karsten Schlüter Karsten Schlüter May 21, 2016 8:44 AM in response to bobfromsaint pete beach
    Level 7 (32,668 points)
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    May 21, 2016 8:44 AM in response to bobfromsaint pete beach

    hm?

    that looks like a green screen recording... and green replaced with black....

     

    or do you want to luma key?

    Bildschirmfoto 2016-05-21 um 17.40.32.png

  • by bobfromsaint pete beach,

    bobfromsaint pete beach bobfromsaint pete beach May 21, 2016 9:07 AM in response to Karsten Schlüter
    Level 1 (4 points)
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    May 21, 2016 9:07 AM in response to Karsten Schlüter

    Let me display captures of the clip I need to work with:

     

    Here is the original - an audience plus stage and curtain -

    Audeince Stage for Alpha Change.jpg

     

    What I want is explained in the rectangle in the capture below -

    Audience for Alpha Change.jpg

    I believe what I want to do is different than just chroma keying but I am all ears & eyes to your counsel.

  • by Karsten Schlüter,

    Karsten Schlüter Karsten Schlüter May 21, 2016 9:17 AM in response to bobfromsaint pete beach
    Level 7 (32,668 points)
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    May 21, 2016 9:17 AM in response to bobfromsaint pete beach

    ... using the Mask tool…

     

    Bildschirmfoto 2016-05-21 um 18.14.42.png

     

    setting Blend mode to Substract ..... ?

  • by bobfromsaint pete beach,

    bobfromsaint pete beach bobfromsaint pete beach May 21, 2016 10:38 AM in response to Karsten Schlüter
    Level 1 (4 points)
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    May 21, 2016 10:38 AM in response to Karsten Schlüter

    You are not understanding my intent. I need a small rectangular section of the stage area to be masked NOT the curtains! And I need the mask to be dynamic - that is grow as the curtain is raised (you cannot see that motion in a still screen capture).

     

    What I have done as a workaround is the following:

    • Created a mask for the rectangular are I showed you in the picture
    • Keyframed the timing and the exposure of the mask to match the curtain rising

    It works but I was hoping I could just permanently remove the alpha channel so there would always be a gap as the curtain rises just ike in real life where you can see the person on the stage starting with hiss feet, then legs, then torso and ultimately the head.

     

    Here is the clip as described in the above bullets: https://youtu.be/vbYD6e4XIto

  • by fox_m,Helpful

    fox_m fox_m May 22, 2016 6:45 AM in response to bobfromsaint pete beach
    Level 5 (5,507 points)
    Video
    May 22, 2016 6:45 AM in response to bobfromsaint pete beach

    The curtain video is from VideoHive? So it has no alpha to begin with (it's a PhotoJPEG codec.)

     

    ok...

     

    Place the video/media you want to reveal over the curtain video. Crop or resize it to the size you need (final).

     

    Draw a Rectangle shape to completely cover the overlay video/media (but not much larger). Line up the bottom of the rectangle with the bottom of the curtains.

    Keyframe a vertical move animation to match the rising curtain. (You might need to keyframe every 5-10 frames to get a decent match.)

     

    Select the overlay video and add an Image Mask (type Command-Shift-M).

    Drag and drop the rectangle shape onto the Mask Layer.

    Go into the Mask inspector and select the Invert Mask checkbox.

     

     

    This is one of many different techniques available in Motion that will accomplish the same thing...

  • by bobfromsaint pete beach,

    bobfromsaint pete beach bobfromsaint pete beach May 22, 2016 6:52 AM in response to fox_m
    Level 1 (4 points)
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    May 22, 2016 6:52 AM in response to fox_m

    Thank you for your reply and validation! That method is actually what I did even before posting my question. I thought maybe working with alpha channel would be more effective than masking.

     

    If you don't mind me tapping your experience and talent for one follow-up question: If I used that mask technique and then exported the project to a rendered video with the ProRes 4444 and No Alpha settings, would I essentially have a template I could use for other projects? What I have donE for now is saved the project so I can swap in a different element behind the screen and as you might expect, it works fine.

     

    Thanks again for your diligent follow-up and sharing your tutorial expertise. I learned a lot!