User-created front ends for Shotcut filters that have not been added to Shotcut

[sauron]

Users have created front ends for some filters. These filters are not in the official Shotcut install package.

All the filters have been key framed except the filters that have no key frameable parameters and the cartoon and binarize filters. I have put these filters on google drive.

Filter front ends.

Users can download and install these filters. They will be available as long as they are not added to the Shotcut install package. If any filter(s) are added to Shotcut they will be removed from google drive.

Installation is simple. Copy the folder to X:\Shotcut\share\shotcut\qml\filters. Where X is the drive where Shotcut is installed. The folders do not need to be renamed. It’s easier to keep track of the added filters that way. Restart Shotcut and the filters will be available for use.

When a new version of Shotcut is installed, if the remove old version option is checked, the filters will be deleted and you will need to add them back if you wish to continue using them.

[Elusien]

Thanks for this.

I’ve almost completed a brand new filter called “Sniper Scope” (see the snapshots below), which I am in the process of producing the QML front-end for. It has lens properties built in and can be turned into a type of “night-scope” by combining it with the “color grading” filter. I’ll publish it on the forum and would appreciate it if you would then add it to the collection.

[Austin]

This is fantastic. How are you going about creating these filters? Are you only adding QML front ends to filters that are already compiled into Shotcut? Or are you also writing C++ code that’s dynamically loaded by Shotcut and then front-ended by QML? Is there a published guide for doing what you’re doing?

[sauron]

@Austin

Are you only adding QML front ends to filters that are already compiled into Shotcut?

Yes that is what we have been doing. @Paul2 started this.

@Austin

Is there a published guide for doing what you’re doing?

I haven’t found one. So far I’ve been doing it by with trial and error. Think I sort of have the hang of it.

Made a UI for a very specialized filter. It’s not complete yet but if some users would like to test it they are welcome to do it.

Light Graffiti.zip (4.1 KB)

A demo can be found here.
https://userbase.kde.org/Kdenlive/Manual/Effects/Misc/Light_Graffiti

[Elusien]

@Austin

Or are you also writing C++ code that’s dynamically loaded by Shotcut and then front-ended by QML?

The Sniper Scope filter I’ve produced I developed from scratch by writing a fragment shader using OpenGL Shader Language (GLSL) and Javascript using a “lens formula” algorithm.

It is quite fiddly doing this as debugging a shader program is like pulling hens’ teeth and optimising the code to make it run faster is quite tortuous e.g to optmise the following code to run twice as fast on the parallel processing GPU:

vec2 new_xy  = rr < SD ? xy * (R - hr) / sqrt(R * R - rr * rr) : xy;
return getFromColor(SC.xy + new_xy);

I had to come up with:

float rr_lt_SD = when_lt(rr, SD);
float RR_gt_rr = when_gt(R , rr);
float sqrt_arg = not(RR_gt_rr) * 1.0 + RR_gt_rr * (R * R - rr * rr);	// prevent sqrt of -ve number error
vec4  colr     = getFromColor(SC.xy + not(rr_lt_SD) * xy + rr_lt_SD * xy * (R - hr) * inversesqrt(sqrt_arg));

Now that the code is complete I have very easily incorporated it the “transitions framework” I put together (see: GL Transitions made using Elusien's GL transitions overlay generator). I am now creating the QML front-end to enable it to be used as a strightforward Shotcut filter with all the keyframe bells and whistles, but this is not so simple.

[Paul2]

@Elusien

That is looking really good.
Two questions:

1. Will it have the ability to adjust the scale, magnification and the position of the sights or can one just apply the S&R filter after?

2. What would be involved to change the shape to say binocular view?
   Was thinking that a gun sight, binoculars and a magnifying glass would all be great additions.

[Elusien]

@Paul2

Will it have the ability to adjust

If you go on my “transition webpage” and click on the “Sniper_Scope” button and then on the “Create Filter” button you will see the HTML code generated for the Overlay HTML filter. The defaults are:

"Mag_Index":1.0,
"Scope_Diameter":0.333,
"Scope_Coords":[0.5,0.8],
"Scope_Color":[0.1,0.1,0.2,1],
"Scope_Thickness":0.04,
"Scope_Only":false,
"Cross_Hairs":true

You can play around with the parameters:

“Mag_Index” is an indication of the magnification (0.0 means no magnification, 1.0 means maximum).

“Scope_Diameter” is the diameter as a fraction of the frame height.

“Scope_Coords” is the point on the frame where the scope is centred.

“Scope_Color” is the normalised [0 to 1] RGBA color of the scope (‘black’ is [0.0, 0.0, 0.0, 1], ‘white’ is [1.0, 1.0, 1.0, 1].

“Scope_Thickness” is the scope’s thickness as a fraction of its diameter.

“Scope_Only” = true if you want to see only the scene inside the scope - the scene outside is blacked out.

“Cross_Hairs” = false, means that you do not want the cross-hairs drawn.

All of these parameters will be available in the QML filter version, plus, appropriate ones will have the ability to be “keyframed”.

@Paul2

change the shape to say binocular view

Don’t forget, when you look though binoculars properly you see a circular view. If you want to simulate binoculars you could apply the filter twice with different X-values for the coords. For a magnifying lens, just omit the cross-hairs and set the scope thickness very thin (say 0.001) just to give a faint outline of the lens.

[Austin]

@Elusien

writing a fragment shader using OpenGL Shader Language

What happens if GPU acceleration is disabled in Shotcut (as it is by default now)? Does your shader get run by an OpenGL software renderer on the CPU? Is that any faster than a pure CPU algorithm? Or is the GLSL route mostly about being easier to integrate into Shotcut so an additional library doesn’t have to be compiled in?

I’m very interested in filter internals, and I have a couple I would like to modify as well. Sorry for my ignorance as I’ve only begun to research it.

[Paul2]

Thank you @Elusien
My questions have been answered and thanks again for a great filter, I shall be tinkering.

[DRM]

@Elusien

I’ve almost completed a brand new filter called “Sniper Scope”

That’s really cool.
How about an option that would allow the user to use different crosshairs of their choice from like a png file?

[sauron]

@Elusien

click on the “Sniper_Scope” button

Can’ find it.

[Elusien]

@Austin

What happens if GPU acceleration is disabled in Shotcut

The “Sniper_Scope” filter is written in GSLS and as such can only be run on the GPU, not on the CPU.

My understanding is that GPU acceleration via OpenGL was added to MLT (and hence Shotcut) in 2013 mainly to implement the “movit” video filter library for high-quality, high-performance video filters based on GLSL shaders (see: MLT - Documentation).

Unfortunately these seem to have introduced some instabilities and a lot of problems have been caused by users switching on “GPU processing”, i.e. using these filters, and not understanding the issues. Hence Dan has disabled them and you have to configure their use manually.

It is unfortunate that people believe that GPU processing is by default disabled in Shotcut. It isn’t. It is the use of these GPU shader programs (movit filters) that have been disabled.

Hence GPU shader programs (like the Sniper_Scope filter or the “transition” filters on my website) can still be used, just not the “movit” ones.

[Elusien]

@sauron

Can’ find it.

http://www.elusien.co.uk/shotcut/gl-transitions/index.html

[Austin]

Everything you said was new information to me. Thanks for the clear explanation.

[Elusien]

@DRM

How about an option that would allow the user to use different crosshairs of their choice from like a png file?

Trying to tie-in a PNG with the sniper-scope filter is probably not possible. Though I have thought about having a reticule on the cross-hairs like so:

[sauron]

My bad. Had to clear the cache for the page to refresh properly.

[DRM]

@Elusien

Unfortunately these seem to have introduced some instabilities and a lot of problems have been caused by users switching on “GPU processing”, i.e. using these filters, and not understanding the issues. Hence Dan has disabled them and you have to configure their use manually.

Would you know of any way of how to go about fixing the GPU issues to help get GPU acceleration complete and up and running?

@Elusien

Trying to tie-in a PNG with the sniper-scope filter is probably not possible. Though I have thought about having a reticule on the cross-hairs like so:

It’d be nice to have at least difference kinds of images of crosshairs to choose from. I don’t know if perhaps there can be an option to just have a circle with no image of a crosshair to allow the user to fill it in with a png image and keyframe it to match?

[Elusien]

@DRM

fixing the GPU issues

It wasn’t really a case of the filters having errors, a lot of the problems were not reproducible. Some problems could have been due t. the order in which filters were applied, or mixing filters on a track. Dan is way more experienced than I at solving problems and he couldn’t do it, mainly because of the unreproducibility issues, Which is why he made the option to switch the filters back on so tortuous. In the past it was too easy to do (just an option in preferences) and the number of error reports this caused was out of proportion to the advantages. Which is why switching it on comes with a health warning.

Type “GPU disabled” into the search box obove and you’ll see what I mean.

@DRM

perhaps there can be an option to just have a circle with no image of a crosshair

There is such an option: Cross_Hairs: false".

[shotcut]

@sauron

All the filters have been key framed

If you are using the KeyframableFilter your QML, then it requires v19.04 of Shotcut (currently only beta) as that is new for this version.

[shotcut]

@Austin

What happens if GPU acceleration is disabled in Shotcut (as it is by default now)?

This option does not affect WebGL, which is used by the HTML filters.