Kernel streaming (KS) refers to the Microsoft-provided services that support kernel-mode processing of streamed data.

Microsoft provides three multimedia class driver models: port class, stream class, and AVStream. The vendor writes a minidriver that runs under one of these three class driver models.

These class drivers are implemented as export drivers (kernel-mode DLLs) in the system files portcls.sys, stream.sys, and ks.sys. In Windows XP and later, ks.sys is referred to as AVStream.

In Windows XP SP2 and later, Microsoft provides the USB Video Class driver.

This section contains legacy documentation on the following topics relevant to the original (pre-XP) ks.sys class driver:

For more information about portcls.sys, see Audio Drivers.

To learn about the stream.sys driver, refer to Streaming Minidrivers.

To read about AVStream, see the AVStream Overview.

DVD Decoder Minidrivers are clients of stream.sys.

Video capture minidrivers can be clients of either stream.sys or ks.sys.

Broadcast Driver Architecture Minidrivers run under AVStream.