Opacity (GPU) for Chroma Key Advanced Issue


I have stumbled upon a bug? error? contradiction? I am not too sure what to call it, however, It is stopping me from reaching my goal with a certain clip.

So what I have observed when using Shotcut filters, I cannot seem to apply the ‘Opacity’ filter to a clip that has already been given the ‘Chroma Key Advanced’ filter, I am able to ADD the filter, but it just does not want to apply the ‘Opacity’ settings onto the clip, the only way for me to apply the filter is to not have the ‘Chroma Key Advanced’ filter applied, which is not the point of interest.

I am using the ‘Chroma Key Advanced’ to filter out and use a greenscreen as an overlay, but when the ‘Opacity’ filter is applied, it does not really seem to do its work.

I will be looking forward for any responses regarding this issue whether it may be a bug, a contradiction rule or if there are/is any alternatives to achieving the goal.

Shotcut version 20.04.12 (currently using)
[ADDITIONAL INFO: I have the GPU Processing feature turned on for smoother playback]

TLDR: Opacity does not work alongside the Chroma Key Advanced filter. Send Help.

The opacity filter works properly. The filter should be applied after the Chroma key filter.



Thanks for the reply Sauron, I just made a quick observation and I am assuming that it works without having the GPU Processing turned on…


As you can see, I have 2 separate tabs which includes GPU and Video, when you have the feature turned on. [I use the GPU processing feature to allow smooth playback]

This video above shows the clip with both the Opacity and Chroma Key filters applied, but the Opacity filter simply does not work.

Now this video above is without the Chroma Key filter, however, the opacity does work BUT you are not able to filter out the greenscreen overlay.

So the problem now becomes;
Not being able to use the Opacity filter with the Chroma Key filter WHILST using the GPU processing feature. I wonder if this is intended or just simply a bug, I assume it is an error due to the fact that if it was the intention to not allow both these filters to be mutual, you would not be able to apply either one of the filters in the first place.

I still do not have any solution…

GPU processing is experimental. It can produce weird results.
My demo was done without GPU processing. Both the Chroma key and opacity filters worked as they are supposed to.


Sorry for asking, but where can I turn on/off GPU for the preview?
(Linux Mint 19.3 Cinnamon, GTX 1060 6 GB with NVidia driver 440)

See here: GPU processing option dissapeared

Be careful though. GPU processing (experimental) uses different filters from non-GPU processing and old projects that used it won’t work without it.

With GPU Effects, all GPU filters are processed before the CPU filters. This is to prevent significant performance degradation by transferring uncompressed video to and from GPU RAM repeatedly. After all, performance is the main reason for using the GPU. As you may have noticed, there is no GPU version of Chroma Key. These are not bugs but rather current limitations.

GPU Effects is unsupported, and that is well known. Shotcut used to issue a warning dialog every time you started the app with that turned on. But after some time, I decided that if you go out of your way to turn on something that is hidden you already understand that and removed the warning dialog.

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Thank you for the reply! This answer was very logical as it has been mentioned that the GPU processing feature is experimental, which never came into my mind. Thanks again! :grinning:

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