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Subunit drivers can use either the Stream class interface or the newer AVStream interface.

For more information about plug connections and data formats, see AV/C Subunit Plug Connection and Format Management. IEC-61883 plug enumeration and control within the kernel-streaming (KS) framework. Subunit drivers receive responses from only their hardware. Routing responses from AV/C subunits to their respective subunit drivers. Virtual subunit drivers must still generate interim and final responses. Avc.sys returns only the final response of an AV/C command or query. Interim responses within the 100 millisecond requirement as defined by the AV/C specification on behalf of peer subunit drivers.

For more information about the format of both peer and virtual subunit device identifier strings, see AV/C Device IDs.Īvc.sys provides the following functionality: Windows then loads the corresponding subunit driver. When an AV/C device connects to the computer, Avc.sys enumerates the active subunits as peer subunits.

The device identifiers associate the correct INF files and subunit drivers with the subunits. For more information about the peer subunit and virtual subunit driver stacks, see AV/C Driver Stacks.Īvc.sys generates device identifiers (IDs) for both peer and virtual subunits. Note that the different modes do not support identical functionality. The Avc.sys virtual mode enables computer functionality to be exposed as an AV/C subunit, and therefore to make the computer a valid target for AV/C commands and requests from other AV/C devices across the IEEE 1394 serial bus.Īvc.sys uses separate driver stacks to support peer subunit and virtual subunits. The Avc.sys peer mode supports subunits on external AV/C devices. These two class drivers make writing drivers for tape subunits unnecessary.Īvc.sys provides two operating modes: peer and virtual. Note that vendors might use the Microsoft-supplied drivers, Msdv.sys or Mstape.sys, to support their tape subunits, if applicable. This section also provides guidelines to develop AV/C subunit drivers for your AV/C-compliant device. This section describes the Microsoft-supplied Avc.sys function driver that provides support for the IEEE 1394 Audio/Video Control (AV/C) protocol.