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Issue - Aplha transition problem - Not proper alpha channel handling on fade transition
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erzyk  
#1 Posted : Monday, June 15, 2020 6:31:31 AM(UTC)
erzyk

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Poland

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Hi,

last time, using vMix as a playout and title system I noticed that the alpha channel on all output behaves faulty on fade transition. I recorded a short video showing this (in the bopttom right corner there is a NDI monitor with checkerboard enabled).
The problem becomes visible every time when I try to fade into a source with transparency (PNG files, vMix titles etc.). The former content is not faded out in alpha channel, but is cut hard on the transition end. It applies to fade and merge transitions. It works perfectry the other way round - fading from content with transparency into something with no transparency.

Link to my recording

The improper transparency fade-in applies to alle alpha (premultiplied and straight) configurations...

What can be the problem with no proper fading out of the alpha channel?
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IceStream  
#2 Posted : Monday, June 15, 2020 9:21:05 AM(UTC)
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@ erzyk

As near as I can tell, that is the default behavior of the "Fade" Transition, that is, the Preview screen fades in overtop of the Program screen (it is not a cross fade where the program screen fades as well).
As such, when using an Input with alpha channel, once the transition is 99% complete, the bottom screen will jump to the preview screen, which will look like a cut because of the alpha channel.


Ice
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erzyk  
#3 Posted : Tuesday, June 16, 2020 12:44:48 AM(UTC)
erzyk

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Poland

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OK, so this means that there is no option to do a crossfade between a source or two sources with alpha?
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DoyleTX  
#4 Posted : Friday, August 12, 2022 3:06:21 AM(UTC)
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Is this still the functionality? Seems like it. I'm experimenting with using vMix as a graphics (and playback) machine with key/fill output. But if it can't do a simple fade without cutting the alpha output, that's just not going to work. Someone suggested a 6 step way of making it work, but to me this just seems like a simple software fade out the program while fading in the preview fix. Kind of frustrating.
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erzyk  
#5 Posted : Friday, August 12, 2022 7:26:16 PM(UTC)
erzyk

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Poland

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@DoyleTX yes unfortunately vMix programmers did not fix this till this day...

The only solution I'm using to get around is to use Fade or Merge transition interchangeably. Check it for your own case, should do the job before they fix it.

Best!
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