acmFilterEnum

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The acmFilterEnum function enumerates waveform-audio filters available for a given filter tag from an ACM driver. This function continues enumerating until there are no more suitable filters for the filter tag or the callback function returns FALSE.

MMRESULT acmFilterEnum(

HACMDRIVER had,
LPACMFILTERDETAILS pafd,
ACMFILTERENUMCB fnCallback,
DWORD dwInstance,
DWORD fdwEnum
);

Parameters
had

Handle of the ACM driver to query for waveform-audio filter details. If this parameter is NULL, the ACM uses the details from the first suitable ACM driver.

pafd

Address of the ACMFILTERDETAILS structure that contains the filter details when it is passed to the function specified by fnCallback. When your application calls acmFilterEnum, the cbStruct, pwfltr, and cbwfltr members of this structure must be initialized. The dwFilterTag member must also be initialized to either WAVE_FILTER_UNKNOWN or a valid filter tag.

fnCallback

Procedure-instance address of the application-defined callback function.

dwInstance

A 32-bit, application-defined value that is passed to the callback function along with ACM filter details.

fdwEnum

Flags for enumerating the filters for a given filter tag. The following values are defined:

ACM_FILTERENUMF_DWFILTERTAG

The dwFilterTag member of the WAVEFILTER structure pointed to by the pwfltr member of the ACMFILTERDETAILS structure is valid. The enumerator will enumerate only a filter that conforms to this attribute. The dwFilterTag member of the ACMFILTERDETAILS structure must be equal to the dwFilterTag member of the WAVEFILTER structure.

Return Values
Returns zero if successful or an error otherwise. Possible error values include the following:

ACMERR_NOTPOSSIBLE	The details for the filter cannot be returned.
MMSYSERR_INVALFLAG	At least one flag is invalid.
MMSYSERR_INVALHANDLE	The specified handle is invalid.
MMSYSERR_INVALPARAM	At least one parameter is invalid.

Remarks
The acmFilterEnum function will return MMSYSERR_NOERROR (zero) if no suitable ACM drivers are installed. Moreover, the callback function will not be called.

The following functions should not be called from within the callback function: acmDriverAdd, acmDriverRemove, and acmDriverPriority.

See Also
WAVEFILTER, ACMFILTERDETAILS, acmDriverAdd, acmDriverRemove, acmDriverPriority

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