Shotcut is a free and open-source cross-platform video editing application for FreeBSD, Linux, OS X and Windows. Started in 2011 by Dan Dennedy, it is developed on the MLT Multimedia Framework, in development since 2004 by the same author. WebVfx, GL-Transitions and Video-Credits are frameworks I have put together to simplify creating various effects. Click on their links above for instruction on using them.
Google Chrome) with its various development tools, then use exactly the HTML and CSS code as an Overlay HTML filter in
Shotcut. The webkit engine used by Shotcut to render the webpage is somewhat out of date. Dan is working on updating this in
a future release of the product. This means that some of the newer HTML5 3D transforms are not available and those that are
have to be prefixed in the CSS by the string '-webkit-'
transform: scale(0, 0) rotate(-180deg); becomes
-webkit-transform: scale(0, 0) rotate(-180deg);).
A transition is a technique used in video editing by which scenes or clips are combined. There is an open-source initiative at gl-transitions.com to provide GLSL shader programs to effect various different types of transition. GLSL is an OpenGL Shading Language with syntax similar to C that is executed directly by the graphics pipeline, which is usually a Graphics Processing Unit (GPU). These shader programs (or Fragment Shaders as they are termed) effectively operate on pixels that come from two sources (usually two clips) and create a target that is some mathematical operation involving these pixels.
WebGL is an implementation of OpenGL ES 2.0 for the Web and is supported by Shotcut's webkit engine.
<canvas> HTML element.
Shotcut's development plan has within it enhancements to incorporate all of these shader programs into the transitions section
of the product. But this is not so simple to do and is probably going to take a while to be released.
Iterfacing these shader programs to Shotcut is not for the faint-hearted, so in the meantime, until they are in the product,
I have created a system to hide the complexity from Shotcut users, by creating a simple Overlay HTML filter, like I do with my (Elusien's) WebVfx Framework.
Unfortunately it is only possible for my system to get the pixels from one source, not two and consequently it cannot produce exactly
the transitions shown on the gl-transitions website. However, by applying the Overlay HTML filter to a Shotcut transition,
rather than to a clip, it is possible for some of them (e.g. 'swirl' and 'pixelise') to produce a good result and others
(such as 'cube' and 'InvertedPageCurl') to produce a reasonable effect, while others (such as the 'BowTie' effects) produce no result at all.
My system makes it possible to input parameters to modify the various aspects of the transition. Be very careful to get the changes right. The filter uses the GPU, which is not very good at recovering from bad coding and it is possible to crash/hang Shotcut if bad values are entered for the parameters. Before applying one of these Overlay HTML filters it is a good idea to save your project, just in case.