This is a collection of sample drivers that demonstrate the basics of writing a WDM audio driver. All the sample drivers use the same "virtual audio device" instead of an actual hardware-based adapter. Each of these samples highlights a different aspect of the WDM audio driver architecture.
This sample collection uses a step-by-step approach to implementing a variety of WDM audio driver features. Each feature is implemented as a separate driver that uses the common classes and services that are implemented in the msvad root directory. Driver developers can use the same framework to implement new features without concern for hardware dependencies. The framework includes implementations of the following interfaces:
· The CAdapterCommon interface gives the miniports access to virtual mixer hardware. It also implements the IAdapterPowerManagement interface.
· The CMiniportTopologyMSVAD interface is the base class for all sample topologies. It has very basic common functions. In addition, this class contains common topology property handlers.
· The CMiniportWaveCyclicMSVAD interface is the base class for all sample wave miniport drivers. It has very basic common functions such as property handlers.
· The CMiniportWaveCyclicStreamMSVAD interface is the base class for all sample wave streams. It implements a timer-based interrupt mechanism to simulate DMA interrupts. Its implementation of the IDmaAdapter interface uses programmed I/O instead of DMA to copy data to memory.
The following table shows the features that are implemented in the various subdirectories of this sample.
|
Subdirectory |
Description |
|
simple |
Basic driver with waveCyclic and topology ports. |
|
multistr |
Implements multiple playback streams. |
|
drmsimp |
Implements DRM for simple. |
|
drmmult |
Implements DRM for multistr. |
|
pcmex |
Implements WAVEFORMATEXTENSIBLE pins. |
|
ac3 |
Implements AC3 pins for playback. |
|
ds2dhw |
Implements DirectSound 2D hardware support. |
To build this sample, start the DDK build environment and run the build command from this directory.
The sample
must be manually installed. It can be
installed via the devcon.exe tool,
which is available as a free download from http://support.microsoft.com/kb/311272,
or it can be installed programmatically via a third-party setup application. The Add
New Hardware wizard is no longer supported in Windows 7.
Devcon source code is also
included elsewhere in the WDK as a sample.
No known issues
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