As it stands now, "fade" only happens on one layer.

Ordinarily, this isn't an issue, or even noticeable.

However, when you're working with something with transparency, such as pictures or video with different aspect ratios (or even a "Transparent" color input), it creates issues.

With a crossfade, where the fade in occurs simultaneously with a fade out, it'd provide a smoother transition for those times when you'd otherwise see the "cut" that's meant to occur in the background.

For those who haven't experienced this, I made a video of the most jarring example--a fade between a Transparent color input and Color Bars.

You'll notice on the fade from the Transparent input to the Color Bars, it looks normal, because the fade is a fade in.

When going the other way, it's still only a fade in, and since the "in" is transparent, nothing fades at all--instead, it cuts at a time that's meant to be covered by the fade in, but isn't when the incoming layer has transparency where the outgoing layer doesn't.



This is, as I said, the most jarring example, but it's universal behavior. A crossfade would provide a smoother transition in these circumstances.

The effect you are looking for is not a crossfade, but to replace all transparent elements with black.
To do this, add a blank input, then add your input as a layer on top of that.

It will then transition as expected.

Hi,

I did indeed read your question in depth, and I did tests to confirm adding a black background does achieve the desired result in your examples.

Perhaps you could provide a different example of what you are looking for, as all the examples you mentioned would be solved with going with a black background.

Regards,

Martin
vMix

I, again, strongly disagree, because it would transition to black, which is not transparent.

I further disagree that anything I said would be solved with a black background, because black is not transparent, but I apologize if that was unclear.

Obviously, the problem would be "solved" by filling the screen with no transparency whatsoever, because the problem is that the new input fades in and then it cuts to eliminate the bottom layer.

That could be done with black, blue, green, and even a full frame image.

The problem is that not everything ever fills the screen or is over a solid color.

Dynamic/animated/video backgrounds are extremely common. Hence transparency, which I keep mentioning for a reason. And that reason is that, as I keep mentioning, I'm dealing in transparency.

If you need specific examples, here's a fade of an 8x10 landscape image to a 4x6 portrait image over an animated background:



And here it is if I take your suggestion:



Yes, it fades now. That was never in question. I even acknowledged from the very beginning that the fade takes place on the top layer and if that layer covers anything, there's no problem.

But you'll notice that both look terrible.

What would look good? A crossfade, that fades in the new layer while simultaneously fading out the old layer so it doesn't just sit there prominently while something comes in on top of it until it just cuts out.

Obviously, if I were dealing in black, this wouldn't be an issue, but as I've now said multiple times, I'm not dealing in black--I'm dealing in transparency.

If you need another example, here's another one I'm dealing with now.

I want to transition from this title:



to this NDI input:



You'll notice that both are on transparent backgrounds, with the black in the first at a translucent alpha level.

This is by design. Because I want to be able to see the background that I am transitioning over.

If I make the background black on each, I will not be able to see the background I'm transitioning over.

As I've said multiple times now, I'm dealing in transparency. And black is not transparent.

Here's how it looks when I cut, using the same background as earlier:



It's a bit jarring for my taste, which is why I want it to Fade. Many would say that being less jarring is pretty much the entire point of a fade.

But here's how that fade looks:



Now, just to hammer my point home, since you requested examples, here's the best case scenario for how it'd look taking your suggestion of putting it over a black background instead of maintaining the transparency like I've specified as crucial since post 1:




Does that help?

When I'd said transparency was crucial and replacing the transparent layers with black wouldn't cut it, I'd kind of expected to be taken at my word without needing to prove that transparency was integral and that replacing it with black wouldn't cut it. Otherwise, I'd have to just replaced it with black in the first place, rather than even posting about this.

I fixed the video links--thanks!

Nothing is going to be completely and utterly perfect, but it'd absolutely be less jarring than the cut out that's happening now.

At something like a 500ms fade, which was in use there, it wouldn't be on screen long enough for people to really register what they're seeing.

In fact, rather than test it with a stable alpha level, I went ahead and checked that first example, via script, using the Overlay method I mentioned a couple comments up.

Since Overlays are the only elements of vMix that fade out, a script that sets a simultaneous in and out is a great way to demonstrate proof of concept with real time animations.

Here's the 8x10 to 4x6 using an Overlay simulated crossfade:



Is it perfect? No, but it's certainly a lot closer than anything posted above.

If you pause it at about 6 seconds, you can see the midpoint thing you're talking about, but at 500 ms (again, the same duration as the previous videos), I can't say I caught it in real time.

The downside of this method is, again, that it only works if you have 2 free overlay channels (I often don't) and it's a hassle to set up.

But I would absolutely accept and benefit from this option, hence why I requested it. Even if you did see the midpoint in real time, I don't think one can really deny that it looks significantly cleaner and smoother than anything I posted above.

There's an old saying about perfect being the enemy of good.

For the pitfalls a crossfade has, I would still find it quite useful, and, in many cases, better than the current options.

EDIT:

Here's the pause I mentioned at 0:06:



Yes, you can see through both layers. But compared to the examples I posted above, it seems like an extremely small issue, especially since, again, it's quite quick in real time.

Ok thanks, I think this feature request is a bit clearer now.
It would essentially be a new transition option only available to a mix input or key/fill output.

It would have to be called something other than crossfade, to avoid confusing to users who would see it dip to black if they used it on an ordinary output expecting it to be a transition.

Something like "Alpha Layer Fade" perhaps.

If I understand this thread correctly this is also something I would like to see implemented.
My use case is using vMix for Fill/Key playout with an ATEM switcher. I managed to do a workaround by transitioning out the Key in ATEM Control, but that way I'm loosing overlays every time I want to fade from vMix to ATEM's program. Another issue with my workaround is having to use two different pieces of software, which I'd like to avoid.