videofilt_introduction

VirtualDub Plugin SDK 1.2

About video filters

Video filter plugins allow custom image processing algorithms to be integrated into VirtualDub's video processing pipeline.

Processing model

The video filter pipeline consists of a linear chain of filter instances, where a video frame enters in the start of the chain and emerges out the back:

start	deinterlace	resize	blur	output

Each video filter instance receives a source frame and a destination buffer and is responsible for processing the frame into the destination buffer. The source and destination sizes can be different, allowing a video filter to shrink or enlarge video as it passes through.

Filter instances do not interact with each other; all interaction is through the host, which moves frames between instances as required.

Sequence transformations

Video filters can also add or remove video frames by controlling the timing of video frames. By default, the output video stream corresponds 1:1 with the input stream, such that frame 547 in the output is a processed version of frame 547 in the input. A video filter can choose to change this mapping, however, allowing frames to be reordered, duplicated, or dropped prior to reaching the filter. It is also possible to change the length and frame rate of the video stream.