Wed
01
Oct 2014

Computer graphics is a broad topic and GPU-accelerated real-time 3D rendering is just one of its parts. Another one is photo and video processing. Video editing is an art by itself, but from the technical point of view there are various interesting effects that can be applied. While not essentially real-time and often done on CPU, of course it could also be GPU-accelerated and also should be as efficient as possible. There are many video editing programs, from Windows Movie Maker to Adobe Premiere. The one of my choice is Sony Vegas Pro. Such programs come with a bundle of standard effects, but for a graphics programmer what can be more fun than writing own plugin?

Vegas Pro supports plugins in OpenFX (OFX) standard. They are written as native code compiled to DLL library with appropriate interface. I'm learning how to write such plugins. Below is a description of how you can start experimenting with this technology plus my "Hello World" example that performs simple color inversion. Maybe later I will write a tutorial with detailed description of this API. For now, here is C++ source code of my example with Visual Studio 2013 project and compiled binaries (Win32 and x64): OfxTest1.zip (21 KB). Inside Vegas Pro it looks like this:

A brief description of how to start coding such plugins:

• Documentation is on openeffects.org website.
• You need to include header files that can be downloaded from Sourceforge > Open Plug-ins For Visual Effects > openfx / openfx-1.3.
• After compilation, you have to rename your DLL to OFX extension and copy it to appropriate location, like: c:\Program Files\Common Files\OFX\Plugins\Basic.ofx.bundle\Contents\Win64\Test1.ofx.
• It must be either 32-bit or 64-bit binary (and appropriate target directory) depending on version of your Vegas Pro.
• I configured copying of this file in VS Project Options as Post-Build Event.
• You have to exit Vegas Pro before overriding this file and then run it again to load and test new version.
• You can debug execution of your code by configuring VS project to run Vegas Pro. All this is set in my example project.
• You can use binary in either Debug or Release configuration. Of course Debug will be slower.

Note that examples provided on SourceForge next to includes package are broken. When compiled in Visual Studio, they assert in Debug configuration due to usage of uninitialized variables and stack corruption! Patch for these bugs is submitted for over 2 years (#1 Basic in Examples - uninitialised variables) and the author is not fixing it. My example has all of this fixed.

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