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Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks

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William Collings
Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 13, 2018 at 7:40:39 pm

So I created a animation, only 6 seconds long of a neon sign, literally pops between being on/off twice, no fade ins/outs or anything like that. Needs to have a transparent background otherwise there's a big black box cover up part of his stream when it goes off.

The animation uses a glow a effect, and literally that's it. But when I attempt to render/export it in all the accepted formats/known to work formats for animations with a transparent background that work with the service, it either breaks the glow animation (I'm ending up with giant red blocks everywhere there should be a glow) or just renders it out with the background.

I tried rendering it in a format that's not supported by the services like stream labs and then converting it to a format that they do with online converters like cloudconvert because there were posts about using it to do just this (minus the glow) and it tossed out a ffmpeg error about the glow.

I've even tried taking PNG's of the animation, replacing the animation with them and just stretching them out since no moving parts thinking that would work, which resulted in the same end product, blocks of red everywhere.

As far as I can tell the entire problem is the glow aspect/need for transparent background, but that's the entire animation itself.

I'm willing to try anything, I've been 2 days at this now for a 6 second animation.


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Steve Bentley
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 13, 2018 at 9:04:08 pm

A couple of things:
First, use a "straight" alpha when you export. Straight extends the image past the alpha's edge and then when you composite later that alpha acts like a cookie cutter trimming the image back to where the image glow really ended. A "premultiplied" alpha can leave a black band around glowing things because the alpha ends exactly where the glow ends, so you are cutting the glow off in the RGB image and then cutting it off again in the alpha, and this can leave a little halo of the background color when composited.

Second thing is that you probably used a "screen" function to put the glow over the neon object. But screen doesn't always render properly when there is no background layer. Screen is a math function but when there are no pixels in a nonexistent background to do the math on you get errors in the image.

One way to go is to render your image as it should be with no alpha but make the glow bigger than it should be. You could also render on the color of the glow instead of black. Then render it again but turn all the color off and crush the levels of some of the elements so you get what amounts to an alpha of the neon with glow - all grayscale but in the RGB channels. Then use that as the track matte when you composite later on.

For both of these techniques make sure to interpret your footage as "Straight" alpha when you import the elements back in to composite. Also make sure if you render out to a movie (like QT) that you choose Millions+ so you get an alpha or RGBA for some other formats.



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William Collings
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 2:09:43 am

Ok you're going to have to break this down a bit more for me. To say I'm "novice" to this would be a understatement, I've been using AE for about a year on and off so I offered to make it for him. I'll attach a png with the glow animation and a example render of how it breaks.

The format I rendered the example video in will only open in media player classic, I had to use that format to get it under 100MB to upload.

https://f1.creativecow.net/file/12530/12530_neonsign11gopro017.png.zip

https://f1.creativecow.net/file/12532/12532_neonsigngpalpha.mov.zip


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Steve Bentley
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 5:55:58 am

I see whats happening.
First, your alphas look good.

I assume the problem is when the light turns off, you see near-black letters when you don't want to see anything. Or you see a big square of black when the letters turn off.

There's two ways to solve this. Have your friend use a Screen function when he supers this footage over his own. Light is additive so its an appropriate way to add a neon sign to a shot. When the light goes out, even though the black letters remain and are part of the alpha it will render properly due the Screen function not letting the black composite on top of the background shot. ("screen" lets pixels of the supered layer "add" to the brightness of the background layer - that is a gross simplification of what the screen function does but its close enough for this). So black pixels won't add any brightness. You could also use "Add" or "Lighter Color" or "Lighten", but for glowy things, "Screen" is usually the best.
If you use the "screen" function you don't even need the matte - rendering your glowing letters element on black with no matte and you will get the same result.
Your "off" letters are slightly pink, just a bit brighter than black so they will still show up a little with a screen function even when the glow is turned off.

The second way is to turn off not just the glow (when the sign is not lit) but also turn off the layer the glow is generated from (the text) during the off-blink, so nothing is left in the alpha for those frames. Then using a "normal" blend mode, the alpha will control what gets composited on the background. If you look at the alpha with this method you will see white glowing letters and then nothing (all black) during the off-blink. Think of the alpha as a mask - the white parts let the RGB channels pass through, the black parts let nothing through.


But I think you would still want to see the structure of the light when the sign is off and that's probably what you were going for with the dark but not black "off" letters. When a neon tube isn't glowing you can still see the tube and the holders for the tube and the metal base that is a backer for the light or the structure of the channel letters, as they are called. At night this isn't as important but can add some good realism. If there are no other lights in the scene to light the underlying structure it's acceptable to just "turn the neon light off" and it's a good enough illusion.
For extra realism don't forget to have other objects close to the sign in the background footage get some of the light that would be coming from the lit letters. This can be done with simple masks. It doesn't have to be much but it really grounds the sign in the shot. The flashlight that lights a page of a book you are reading is also bouncing off the page and lighting up the room too.
I think what you have here is correct, but perhaps not what you were expecting.

The only other comment is that neon or nighttime signage tends to blow out and over exposes at the core of the text. Like a lightsaber, the center tends towards white or a hot version of the actual color. Go watch Blade Runner (the original). This sign doesn't really look like its glowing because its not "hot" enough. You can also try duplicating the sign layer and screening it again over its twin and the background - this will keep adding to the glow and core brightness. Also try Hardlight and Vividlight blend functions as they might be better to kick the brightness up. You can also add a Glow effect to the sign layer - but I don't like the Glow effect's roll-off and prefer just adding multiple copies with a blend function that works best.

Keep in mind that if you deliver this element in a compressed format - like H.264 - the alpha will be thrown away.

Let me know if I still haven't hit the heart of the problem.



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William Collings
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 5:59:05 pm

Ok I might have confused you, either that or you didn't see what I see in the video? I'll include a screenshot of what I see in the video and what it looks like when trying to render with alpha in the needed formats.

The problem is not the black/darkened letters. The problem is there is supposed to be no background, it needs to be transparent, but when I render with alpha, it either breaks and turns into this image , or keeps the background for no apparent reason depending on the format selected. Sometimes both.

https://f1.creativecow.net/file/12535/12535_ccshow.png.zip


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Steve Bentley
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 6:19:14 pm

That's the pure RGB you are seeing. If you take the PNG or the movie into AE you don't get that (assuming you interpret for an alpha).
Perhaps what ever you are looking at it in can't handle an alpha or you just opened it in pshop or media player. With these you will only ever see the RGB on its own, but in pshop you can apply the alpha a a mask to produce the final result.
You are doing everything right, it might just be how and where you are viewing the render.

I would not complain if someone gave me this element to work with in AE. It's alpha is correct for the look you are after and composites perfectly.



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William Collings
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 7:52:35 pm

Oh, you were right! It's strange because even on my desktop is was showing as that, but it works in the streamlabs preview! Guess I need to start double checking my work in that. Thank you! You helped me sort this out so much quicker than I thought it would be, I've been 3 days trying to figure out what went wrong.


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Dave LaRonde
Re: Created a glow animation for a streamer/friend, transparent background, when trying to export/render it to a format that streamlabs accepts animation always breaks
on Jul 14, 2018 at 11:37:43 pm

There's a good, fsil-safe method to check alpha channels on animations.

Blow off the viewers and import them into a video editing application.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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