Kernel Streaming Minidriver architecture and KS Filters
Kernel Streaming (KS) refers to the Microsoft-provided services that support kernel mode processing of streamed data. In this model, streaming data flows through a series of nodes that are grouped into blocks called filters. Each filter encapsulates some processing task to be performed upon the data. A KS filter is implemented as a kernel mode driver object. Microsoft provides three multimedia class driver models that expose streaming functionality to the hardware vendor. These are Port Class, Stream Class and AVStream.
WDM Audio Drivers (Port Class)
The WDM audio architecture is based on KS (kernel streaming) services. WDM audio drivers control audio adapter cards that render and capture streams containing audio data in wave and MIDI formats.
AV Stream Minidrivers
The AVStream part of the operating system is accessible through the OS supplied export driver ks.sys. Developers write AV Stream minidrivers that can expose audio and video pins. The legacy stream class driver model is still supported only for existing minidrivers.