DirectShow

DirectShow is a multimedia framework and API developed by Microsoft for Windows to perform streaming media tasks, including playback, capture, and processing of audio and video. It is based on the Component Object Model (COM) and is part of the DirectX technology family. DirectShow provides a programmable pipeline for handling media data in a flexible, filter-based architecture.

The core concept of DirectShow is the filter graph, assembled by the Graph Manager. A graph consists of filters connected by pins: source filters bring in data, transform filters decode or convert data, and render filters output the final result. Additional filters can perform encoding, effects, or format conversion. The data flow through the graph is controlled by interfaces such as IGraphBuilder, IMediaControl, IMediaEvent, and IBaseFilter, while pins and connections define the path through the pipeline.

DirectShow relies on a broad ecosystem of filters, including codecs supplied by the operating system or third parties. It can render video and audio to the appropriate devices, capture from cameras and other capture hardware, and process streams from local files or network sources. Debugging and graph construction were historically aided by tools like GraphEdit, and rendering options have included overlays, video renderers, and modern hardware-accelerated renderers.

History and status: DirectShow originated in the late 1990s under the name ActiveMovie and was later integrated into DirectX as DirectShow. It was a dominant Windows media framework through the Windows XP and Windows 7 eras. In subsequent Windows versions, Microsoft introduced Media Foundation as a newer multimedia framework, but DirectShow remains supported for compatibility and is still used by many applications and libraries.

See also: Media Foundation, GraphEdit, Windows SDK.