Transparent Video in Stride

[ravel]

Hi there, I am working on an AR Project and would like to use stride this time.

One major feature I need is having a Transparent Video played on an geometrie like a plane.
At the moment I am loading a image stack of PNGs into the filetexture and select each image (30 fps) via index of an getSlice. It works for small videos, but there is no function for preloading the next images.

Than I try to get a nice looking result out of the transparent texture. The half transparent pixels are not transparent. I tried to use the blend (trancparency.MaterialAttribute) in the combination with the same texture for alpha. Doesn’t work.
Now I created a project in Stride. The material with the transparency of an image looks great, but how do I replace the Texture Image with a Video?

Looking forward to your thought on this topic and would be so grateful about help.

[sebl]

you could add a green background to your video instead of alpha and then use a chromakey tfx.

that way you could use e.g. vl.mediafoundation to play the videos

[ravel]

[ravel]

was thinging about it. How does the keying look like in the edges of the graphics? Isn’t in the half transparent area leftovers from the color?

[sebl]

try it out. you can tweak the edges with the chromakey parameters.

it depends on your usecase

[bjoern]

There are codecs/containers that support alpha in video. For example VP9/webm.
Sample attached.

While the video plays nicely with alpha in firefox and chromium for example - either embedded in html or just the video-file - the alpha channel is ommited when played back using vl.mediafoundation. Just quickly skimming the code I couldn’t find any obvious reasons. Also a short search didn’t yield any answers concerning the support of alpha channel in videos in media foundation.
Maybe @elias can shed some light on this.

VL.Cef Webrenderer supports alpha in webm if the video is embedded in html. So if you don’t need much control over the video, e.g. just a loop, this could be an option.

WebmTest.7z (146.5 KB)

[tonfilm]

Btw, latest preview has a mediocre help patch for keying with TextureFX.

[ravel]

Thank you so much for your help. Usually I am to shy to write in the Forum (Gamma is forcing me :/). Now I am so happy to learn from you.
I tried the Webm Version. could be I’m getting stucked with the same Problem. How to get a alpha Texture on a Stride model?

WebmTest.zip (151.1 KB)

[LukeMc]

I had a similar problem yesterday - maybe this could help?

Stride - Transparency in materials?

Thank you, I have it now. For anyone else with the same question, here’s a patch. [image] I had to turn on advanced and experimental in the node search, to find those nodes. And it’s worth reading that page of the stride docs, as the alpha behaviour switches above 0.5. Still working out how that works. Also, it doesn’t seem to take effect when the patch is loaded - I have to toggle the group on and off

[bjoern]

mh. discourse seems to destroy gifs.
https://imgur.com/a/O7RG7KB

[ravel]

@bjoern

https://imgur.com/a/O7RG7KB

ahhh. Here we go. I didn’t turn the Cast Shadow off. Great !!! thank you so much!

[ravel]

I went a different way now. Using a black and white alpha Channel video to key out the alpha. Just need to sync the videos now. Is seeking the videos to a stopwatch a good idea in Gamma?

[sebl]

You can combine both videos in one, where you later grab the rgb part and the mask. You then also need only one player.

[ravel]

@sebl how can I combine the videos?

[tonfilm]

i think what sebl means is that you use your video editor to make one video where the image and the mask are combined. either side-by-side or over-under, much like 3d movies store the left and right eye. if you do that, your mask and the image can never run out of sync.

then you combine the mask with the image in a TextureFX to get the final video texture with alpha channel.

[antokhio]

You also can use LumaKey or ChromaKey, if you video is on solid color background…

[ravel]

Ah, good idea to have two videos next to each other. thanks.
And I’ll try the chromakey at some stage, too. I just don’t want to have the hassle with keying out stuff by accident.

Thank you all so much for your support. Best community ever !!! : *

[bjoern]

Need some HINTS for research - Stride - SystemOutOfMemoryException

Here we go, inside you find a little demo patch showing howto load (and unload) a set of textures. I was testing it with 1280p *.bmp files I generated with ffmpeg before. It should also allow to do what you need, having 25 of out 3000 loaded at a time. You’ll need at least version 2021.3.0-21 for it to run. TextureLoader.vl (57.2 KB)