ACMDRVOPENDESC

This structure is used by the ACM for passing information to an ACM driver after the ACM sends the driver an ACM_Open function.

Syntax

typedef struct {
DWORD cbStruct;
FOURCC fccType;
FOURCC fccComp;
DWORD dwVersion;
DWORD dwFlags;
DWORD dwError;
LPCSTR pszSectionName;
LPCSTR pszAliasName;
DWORD dnDevNode;
} ACMDRVOPENDESC;

Members

cbStruct

Specifies the size, in bytes, of the structure.

fccType

Contains a four-character code identifying the driver type. The driver must compare this value with ACMDRIVERDETAILS_FCCTYPE_AUDIOCODEC, which is declared in the Msacm.h header file, to equal the string “audc”. If the member contents do not match this string, the driver must fail the open request by specifying an ACM_IOControl return value of 0.

fccComp

Not used. Defined to contain a four-character code identifying the driver sub-type.

dwVersion

Specifies the ACM’s version number. The version number format is 0xAABBCCCC, where AA is the major version number, BB is the minor version number, and CCCC is the build number. This value is also returned by the ACM’s acmGetVersion function.

dwFlags

No flags currently are defined. This member is identical to the fdwOpen argument passed to the acmDriverOpen function.

dwError

Specifies an error value. Drivers are restricted to specifying an ACM_IOControl return value of 0 for all error types. To provide better error resolution, ACM drivers can specify an error value in this member if they set the ACM_IOControl function’s return value to 0. The error value can be one of the MMSYSERR error values declared in the Mmsystem.h header file or one of the ACMERR error values declared in the Msacm.h header file.

pszSectionName

Pointer to the registry key under which the driver’s alias is stored. For more information, see the Windows NT Device Driver Kit.

pszAliasName

Pointer to the driver’s alias. This is the driver’s Msacm. alias entry in the registry. For more information, see the Windows NT Device Driver Kit.

dnDevNode

Specifies a device node identifier.

Remarks

When the ACM calls an ACM driver’s ACM_IOControl entry point and specifies a DRV_OPEN message, it includes an ACMDRVOPENDESC structure as the lParam2 member to ACM_IOControl. The ACM sends a DRV_OPEN message when an application calls the acmDriverOpen function.

This structure is declared in the Msacmdrv.h header file.