ACMDRVSTREAMINSTANCE
typedef struct {
DWORD cbStruct;
LPWAVEFORMATEX pwfxSrc;
LPWAVEFORMATEX pwfxDst;
LPWAVEFILTER pwfltr;
DWORD dwCallback;
DWORD dwInstance;
DWORD fdwOpen;
DWORD fdwDriver;
DWORD dwDriver;
HACMSTREAM has;
} ACMDRVSTREAMINSTANCE;
The ACMDRVSTREAMINSTANCE structure describes an instance of a conversion
stream. ACMDRVSTREAMINSTANCE is defined in msacmdrv.h.
Members
-
cbStruct
-
Contains the size, in bytes, of the ACMDRVSTREAMINSTANCE structure.
-
pwfxSrc
-
Pointer to a WAVEFORMATEX structure that defines the source format for a
conversion stream. (WAVEFORMATEX is described in the Win32 SDK.)
-
pwfxDst
-
Pointer to a WAVEFORMATEX structure that defines the destination format for a
conversion stream.
-
pwfltr
-
Pointer to an optional WAVEFILTER structure that defines a filter to be used
on a conversion stream. This member is NULL if the application has not
specified a filter. (WAVEFILTER is described in the Win32 SDK.)
-
dwCallback
-
Contains the application-specified dwCallback argument to the acmStreamOpen
function.
-
dwInstance
-
Contains the application-specified dwInstance argument to the acmStreamOpen
function.
-
fdwOpen
-
Contains the application-specified dwOpen argument to the acmStreamOpen
function, which consists of a set of flags. (For flag descriptions, refer to acmStreamOpen
in the Win32 SDK.)
-
fdwDriver
-
Contains driver-defined stream instance information. While intended for
storing flag values, an ACM driver can use this member to store any
instance-specific DWORD value. Because the same ACMDRVSTREAMINSTANCE structure
is passed with all stream messages associated with a particular stream
instance, the stored value can be read or modified each time a stream message
is received, and the last saved value will be available the next time a stream
message is received.
-
dwDriver
-
Contains driver-defined stream instance information. An ACM driver can use
this member for storing any instance-specific DWORD value, such as a pointer
to a local, dynamically allocated structure. Because the same
ACMDRVSTREAMINSTANCE structure is passed with all stream messages associated
with a particular stream instance, the stored value can be read or modified
each time a stream message is received, and the last saved value will be
available the next time a stream message is received.
-
has
-
Contains the ACM-defined client handle to the open conversion stream.
Comments
The ACM allocates an ACMDRVSTREAMINSTANCE structure each time an application
calls acmStreamOpen. This ACMDRVSTREAMINSTANCE structure is then passed
to the driver with all stream messages associated with a particular stream
instance. Information in the structure does not change, so if a driver
validates information within the structure when it receives an ACMDM_STREAM_OPEN
message, it does not have to validate the information again when it receives
subsequent messages for the same stream instance.