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Microsoft supports the Audio Video Control (AV/C) protocol, which is built upon the IEC-61883 standard.
The AV/C protocol driver Microsoft supplies is called avc.sys. It is a functional driver that supports the AV/C subunit protocol. The AV/C subunit protocol is a method for issuing commands and sending responses from subunits on devices such as MiniDV camcorders and digital-VHS tape decks. For example, a MiniDV camcorder has two subunits, a camera subunit (the imaging device) and a tape subunit (storage of the media-signal). A digital-VHS tape deck has a tape subunit and a tuner subunit. These subunits can be controlled externally from a computer if the device is connected to a system through the IEEE 1394 serial bus and appropriate drivers are written for the subunit hardware. These drivers are WDM drivers that connect to the AV/C system-supplied driver (avc.sys) to provide that control.
An AV/C unit, such as a Digital Video camcorder (DV) or Digital VHS (DVHS) tape deck, can stream isochronous data over the IEEE 1394 bus using the IEC 61883 specifications. When an AV/C device is connected to a computer with the Microsoft® Windows® XP operating system, it is enumerated as an AV/C device by two lower protocol drivers: avc.sys and 61883.sys. Drivers of these devices are called AV/C subunit drivers. These drivers are written as Windows Driver Model (WDM) architecture and Kernel Streaming (KS) minidrivers.
An AV/C subunit driver in general supports:
An AV/C subunit driver can use services provided by the AV/C protocol driver (avc.sys) to perform device control, and use the 61883 protocol (61883.sys) driver to provide connection management and data streaming.
See IEC-61883 Client Drivers for more information about the 61883 protocol.
Microsoft also supplies an optional streaming filter driver that aids in the processing of two specific data formats: standard definition digital video (SDDV, or the 61883-2 specification) and MPEG2TS (or the 61883-4 specification).
The optional AV/C Streaming filter driver is called avcstrm.sys. It resides between individual subunit drivers and functional driver, avc.sys.
The following sections include the design guides for the AV/C protocol driver and AV/C Streaming lower filter driver:
AV/C Protocol and Subunit Driver Support
The following sections include the enumerations and structures used by AV/C and AV/C Streaming: