acmFilterEnum function (msacm.h)
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.
Syntax
MMRESULT ACMAPI acmFilterEnum(
HACMDRIVER had,
LPACMFILTERDETAILS pafd,
ACMFILTERENUMCB fnCallback,
DWORD_PTR dwInstance,
DWORD fdwEnum
);
Parameters
had
Handle to 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
Pointer to 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 (DWORD), 64-bit (DWORD_PTR) 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.
[ACMFILTERDETAILS](./nf-msacm-acmfilterdetails.md) 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.| Value | Meaning |
|---|---|
| ACM_FILTERENUMF_DWFILTERTAG |
Return value
Returns zero if successful or an error otherwise. Possible error values include the following.
| Return code | Description |
|---|---|
|
The details for the filter cannot be returned. |
|
At least one flag is invalid. |
|
The specified handle is invalid. |
|
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.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | msacm.h |
| Library | Msacm32.lib |
| DLL | Msacm32.dll |