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Lower third bar length expression

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alex judson
Lower third bar length expression
on Sep 19, 2013 at 6:45:25 pm

Hi all, I'm new to scripting and am having quite a bit of trouble trying to figure this one out. Any help would be appreciated.

I am trying to create a lower third bar that will cover a change of text underneath it. It needs to be modular to cover different lengths of messages, and be easy/quick to change from one length to another.

What I have so far is a comp "MATTE_LENGTH" with 5 layers (1X_BAR, 2X_BAR, 3X_BAR…) that have position keyframes in X-axis. Each layer has different keyframes to get a solid to move across the frame and back at custom lengths/timings. In the main comp "BAR_WIPE" I have the nested "MATTE_LENGTH" pre-comp, another pre-comp "BAR" with a simple solid bar that does not animate and a third "MATTE" layer. The "BAR" layer uses the "MATTE" layer as a matte. The "MATTE" layer has this expression on the X Position attribute:

comp("MATTE_LENGTH").layer("5X_BAR").transform.xPosition


This works well, but I have 2 problems. If I slide any of the layers in the main comp, all the timings come from the comp "MATTE LENGTH" and I lose the animation. Also I have to manually change the expression to adjust the length to 1X_BAR, 2X_BAR, 3X_BAR… etc. and this leaves room for error. Is there a way to control the lengths from a checkbox or slider control? and is there a way to add a start time to the expression?

here is a link to the aep:
https://www.hightail.com/download/OGhmV284Q1BrWThLSk1UQw

Thanks in advance,
Alex


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Kevin Camp
Re: Lower third bar length expression
on Sep 21, 2013 at 9:32:13 pm

I'm not near AE right now, so i can't tell for sure what your trying to do.... But You may find this trick helpful. You can make a plate that is the exact size of your text by ganging up several effects on your text layer.

First add fast blur and set it to 5 or so.

Then add the shift channels effect and set alpa to full.

Add an effect to change the color, like fill, ramp or 4-color gradient, etc.

Then add cc composite to put the text on top of the bar.

At this point the bar will change size depending on what you type. You can adjust the size of the bar with the blur. You can separate the height and width by duplicating the fast blur and setting one to vertical and the othe to horizontal. You can adjust the opacity of the bar by adding transform prior to cc composite and setting the opacity there.

Hopefully that can help you out. If I get a chance I'll take a look at your project.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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greg janza
Re: Lower third bar length expression
on Jan 28, 2014 at 10:31:25 pm

kevin- thanks for that tip. it works great. one thing that I'm running into though is that when I bring a rendered tiff file with alpha into fcp7 and lay it on top of my video the white text is not 100% on top but it instead it has partial opacity. my bar is set to 75% opacity by way of your suggestion to use transform. How do I set the cc composite effect to make the text have 100% opacity? thanks!


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greg janza
Re: Lower third bar length expression
on Jan 29, 2014 at 12:46:20 am

no need to respond kevin. I noticed that if you uncheck the RGB only box within cc composite the text has full opacity.


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Peter Dowson
Re: Lower third bar length expression
on May 3, 2018 at 9:19:32 am

OMG thank you thank you thank you!
I was searching for just this solution to make life even sweeter with editable dynamic linked lower thirds and automated background in premiere :)


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