Share via

IWMDMDeviceControl::GetCapabilities

  • Article
banner art

The GetCapabilities method retrieves the device capabilities to determine what operations the device can perform. The capabilities describe the methods of the device control that are supported by the media device.

Syntax

HRESULT GetCapabilities(DWORD*pdwCapabilitiesMask);

Parameters

pdwCapabilitiesMask

[out]  Pointer to a DWORD specifying the capabilities of the device. The following flags can be returned in this variable.

Flag Description
WMDM_DEVICECAP_CANPLAY The media device can play MP3 audio.
WMDM_DEVICECAP_CANSTREAMPLAY The media device can play streaming audio directly from the host computer.
WMDM_DEVICECAP_CANRECORD The media device can record audio.
WMDM_DEVICECAP_CANSTREAMRECORD The media device can record streaming audio directly to the host computer.
WMDM_DEVICECAP_CANPAUSE The media device can pause during play or record operations.
WMDM_DEVICECAP_CANRESUME The media device can resume an operation that was paused.
WMDM_DEVICECAP_CANSTOP The media device can stop playing before the end of a file.
WMDM_DEVICECAP_CANSEEK The media device can seek to a position other than the beginning of a file.
WMDM_DEVICECAP_HASSECURECLOCK The media device has a secure clock.

Return Values

The method returns an HRESULT. Possible values include, but are not limited to, those in the following table.

Return code Description
S_OK The method succeeded.
E_INVALIDARG The pdwCapabilitiesMask parameter is an invalid or NULL pointer.
E_FAIL An unspecified error occurred.

Remarks

Currently, not many devices report their capabilities correctly.

Example Code

The following C++ code retrieves the device capabilities.

// Examine the device capabilities.
// Use some of these to enable or disable the application's
// user interface elements.
CComQIPtr<IWMDMDeviceControl> pDeviceControl(pIWMDMDevice);
if (pDeviceControl != NULL)
{
    DWORD caps = 0;
    hr = pDeviceControl->GetCapabilities(&caps);
    if (caps & WMDM_DEVICECAP_CANPLAY)
    {
        // TODO: Display a message indicating that the media device can play MP3 audio.
    }
    if (caps & WMDM_DEVICECAP_CANSTREAMPLAY)
    {
        // TODO: Display a message that the device can play audio directly from the host computer.
    }
    if (caps & WMDM_DEVICECAP_CANRECORD)
    {
        // TODO: Display a message that the device can record audio.
    }
    if (caps & WMDM_DEVICECAP_CANSTREAMRECORD)
    {
        // TODO: Display a message that the media device can record 
        // streaming audio directly to the host computer.
    }
    if (caps & WMDM_DEVICECAP_CANPAUSE)
    {
        // TODO: Display a message that the device can pause during play or record operations.
    }
    if (caps & WMDM_DEVICECAP_CANRESUME)
    {
        // TODO: Display a message that the device can resume an operation that was paused.
    }
    if (caps & WMDM_DEVICECAP_CANSTOP)
    {
        // TODO: Display a message that the device can stop playing before the end of a file.
    }
    if (caps & WMDM_DEVICECAP_CANSEEK)
    {
        // TODO: Display a message that the device can seek to a position 
        // other than the beginning of the file.
    }
    if (caps & WMDM_DEVICECAP_HASSECURECLOCK)
    {
        // TODO: Display a message indicating that the device has a secure clock.
    }
}

Requirements

Header: Defined in mswmdm.h.

Library: mssachlp.lib

See Also