[Guide written using Keysight 1.6.2 and Da Vinci Resolve 18.5]

Welcome! It's a very common request to have a video running "behind" Keysight. Unfortunately, this is not possible natively within Keysight itself; but a few extra minutes of work and you can get a result like this!

You will need:

• To be in the Advanced mode in the menu
  
• Two renders of your midi file. One "normal" render, and one "mask" render. We'll go over this more in the next section, but this template may help[drive.google.com]
  
• A video editor. I am using Da Vinci Resolve (the free version) because I know a lot of people are doing the same, and I have prepared this Fusion Composition template.[drive.google.com] I have also outlined a method to get this working in Adobe Premiere Pro as well

First thing's first, you want to disable any fade-in / fade-out for your render in Midi > Post FX. Having a fading render will result in opacity weirdness in the final composition.


Next, render out your video as normal


Now we need to make a black and white render of this same preset in order to have information on what should be opaque, and what shouldn't be. This .kspreset file[drive.google.com] could be a useful shortcut, but let's break down what needs to happen to go from a "normal" preset to a "mask" preset (and fair warning, this is an Advanced guide, so I'm not going to screenshot every single menu toggle in the interests of not having a colossally long guide)...

• Disable all effects other than Note Objects
  
• If Note Objects have a Border, make sure this is removed with Note Objects > Border > Shape, None
  
• Set Note Object material to "Basic", with an emissive strength of 2.25
  
• Set Note Object colour to Static mode, with one slot of pure white
  
• Disable Scene Lights and Light Bars under Widgets
  
• Under Scene > Lighting, set Bloom Strength to 0.00 and Void Colour to pure black
  
• Under Scene > Frame, enable "Frame uses custom material" and set that material to Basic, white emissive colour, with 2.25 emissive strength. Copy this material using the little icon on the left above the material modes
  
• Scene > Piano, enable "Piano is replaced with flat plane", disable "Show piano felt", and paste the copied material to White Key Material
  
• If using Damper Visualisation, Scene > Damper visualisation > Material, enable "use custom material" and paste your copied material
  
• Scene > Backdrop, set backdrop to use a Basic material with pure black colour
  
• If using Octave Lines, Scene > Octave Lines, paste your copied material

If you want to use the Mask.kspreset file[drive.google.com] and your intended preset is pretty "stock": simply make sure the Note Object shape is set to match the intended preset and you should be good to go! (So if your intended preset uses Flat notes, the Mask.kspreset is in Rounded by default and you will need to change it to Flat)

Now that you have a Mask preset, simply re-render your midi file using it! You may want to make sure you have 4:1 pixels per pixel under Quality for this one, so the edges of note objects are nice and smooth once masked over the top of a video.

This portion of the guide uses Da Vinci Resolve and a Fusion node composition export to make the process of adding a video background very quick and easy. But if you happen to be a Premiere user and do not wish to learn Resolve (I don't blame you, I'm pretty set in my ways in using Premiere), then skip down to the next section!

Here is a quick video showing the whole process, and then we'll break it down into text and screenshots

Make a new project, switch to Edit mode, and add your video background + normal render + mask render to the media pool


Add your normal render to the timeline


Head into the Fusion tab


Head to File > Import > Fusion composition and select this file[drive.google.com]


Drag and drop each video into the respective box


Connect the square from each media source to the corresponding yellow inputs in the node graph. The "normal render input" needs to connect to both AlphaMul nodes


Done! Now simply head back to Cut or Edit and continue on with your editing process as desired

This method is slower since I cannot just export a template for you to plug videos in to, but since I figured out how to do it in Premiere I guess I might as well very quickly outline how!

• Have 5 video tracks
  
  
• In track 1, place your background video
  
• In track 2, place the Keysight normal render
  
• In track 3, place the Keysight normal render again
  
• In track 4, place the Keysight mask render
  
• In track 5, place the Keysight mask render again
  
  
• On track 2's normal render: add a Track Matte Key effect and set the Matte to Video 4, and Composite Using: "Matte Luma"
  
• On track 3's normal render: add a Track Matte Key effect and set the Matte to Video 5, and Composite Using: "Matte Luma"
  
• On track 3's normal render: open the Opacity effect tab, then expand "Opacity" again and change Blend Mode to "Lighten"
  
  
• Nothing needs to be done on track 4's mask render
  
• On track 5's mask render: add an Invert effect

Consider nesting all these tracks together to make it easier to work with, but Keysight should now be nicely blended over the background video!

• Fundamentally, we're rendering a second video which contains the opacity information for "solid" objects as a luminosity (brightness)
  
• We then use that mask to isolate the solid parts of our render so we can overlay these onto the video as-is
  
• Then we use the mask again, but inverted this time, to isolate the non-solid parts of the render
  
• These non-solid pixels are then *additively* overlaid onto the background to keep them semi-transparent

This method is far superior to things like chroma or luma keying a single render, thanks to not having to "guess" what should be transparent and what shouldn't be. It also allows dark objects to be solid, as opposed to simply additive-blending the whole render and then having ghostly notes if the notes are not 100% bright!

- Use this Mask.kspreset file[drive.google.com] and make sure the note shape in the mask is the same as your target preset
- Render your target preset and the Mask preset with no fade-in / fade-out on the render
- Import the intended video background and both Keysight renders to a new Resolve project
- In the Fusion tab, File > Import > Fusion Composition and use this file[drive.google.com]
- Place relevant videos in each bubble and connect them to the yellow triangles (Colour needs to go to both AlphaMul)