DirectShow is a Microsoft programming interface for working with media files. DirectShow is used by a number of Microsoft and third party software including windows media player and Fast video indexer. Is comes installed with all windows operating systems.
DirectShow is a component based system that is used by applications to solve a number of different problems. An application can for example use the framework to playback videos, capture videos, do video processing and to do real time video analysis.
How DirectShow works
A DirectShow application connects a number of DirectShow components called filters into a filter graph. A filter graph typically has a reader filter to read a media file either from file or from a live stream like a web page or a web camera, a DirectShow decoder filter ie a codec and finally a rendering filter. Filter graphics can contain several different types of media but the most common are video and audio streams.
Capture video frames with DirectShow
Fast video indexer uses the DirectShow programming interface with standard direct show decoder filters to capture video frames. When you want to use fast video indexer to capture frames from a file the computer running fast video indexer needs to have a DirectShow decoder filter or codec for the media file format installed. Windows and windows media player has a number of filters preinstalled.
Supported files in DirectShow
Since DirectShow is really a framework connecting a number of different filter and it can be extended with more filters as needed. Most applications use a filter graph builder that will allow it to use filter that the author of an application might not even know of or that wasn’t available when the application was created. DirectShow has support for avi and vfw files in windows by default but extra filers can be downloaded to support just about any video format.
DirectShow and QuickTime
QuickTime is not supported by default in QuickTime and if you download the QuickTime player you will not get the required filters. Read this article about how you can play and capture video frames from QuickTime files.