ACMDRVSTREAMINSTANCE (Windows Embedded CE 6.0)

1/6/2010

This structure describes an instance of a conversion stream.

Syntax

typedef struct {
  DWORD cbStruct;
  LPWAVEFORMATEX pwfxSrc;
  LPWAVEFORMATEX pwfxDst;
  LPWAVEFILTER pwfltr;
  DWORD dwCallback;
  DWORD dwInstance;
  DWORD fdwOpen;
  DWORD fdwDriver;
  DWORD dwDriver;
  HACMSTREAM has;
} ACMDRVSTREAMINSTANCE;

Members

• cbStruct
  Value that specifies the size, in bytes, of this structure.

• pwfxSrc
  Pointer to a WAVEFORMATEX structure that defines the source format for a conversion stream.

• 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.

• dwCallback
  Value that specifies the application-specified dwCallback parameter of the acmStreamOpen function.

• dwInstance
  Value that specifies the application-specified dwInstance parameter of acmStreamOpen.

• fdwOpen
  Value that specifies the application-specified dwOpen parameter of acmStreamOpen, which consists of a set of flags.

• fdwDriver
  Value that specifies driver-defined stream instance information. Although it is 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 is available the next time a stream message is received.

• dwDriver
  Value that specifies 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 is available the next time a stream message is received.

• has
  Value that specifies the ACM-defined client handle to the open conversion stream.

Remarks

The ACM allocates this structure each time an application calls acmStreamOpen. This structure is then passed to the driver along with all stream messages associated with a particular stream instance. Information in this structure does not change, so if a driver validates information within this 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.

Requirements

See Also

Reference

ACM Driver Structures

Other Resources

WAVEFORMATEX (Waveform Audio)