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The acmFilterEnumCallback function specifies a callback function used with the acmFilterEnum function. The acmFilterEnumCallback name is a placeholder for an application-defined function name.
Syntax
ACMFILTERENUMCB Acmfilterenumcb;
BOOL Acmfilterenumcb(
HACMDRIVERID hadid,
LPACMFILTERDETAILS pafd,
DWORD_PTR dwInstance,
DWORD fdwSupport
)
{...}
Parameters
hadid
Handle to the ACM driver identifier.
pafd
Pointer to an ACMFILTERDETAILS structure that contains the enumerated filter details for a filter tag.
dwInstance
Application-defined value specified in acmFilterEnum.
fdwSupport
Driver-support flags specific to the driver identified by ACMDRIVERDETAILS structure, but they are specific to the filter that is being enumerated. This parameter can be a combination of the following values and identifies which operations the driver supports for the filter tag.
| Value | Meaning |
|---|---|
| ACMDRIVERDETAILS_SUPPORTF_ASYNC | Driver supports asynchronous conversions with the specified filter tag. |
| ACMDRIVERDETAILS_SUPPORTF_CODEC | Driver supports conversion between two different format tags while using the specified filter. For example, if a driver supports compression from WAVE_FORMAT_PCM to WAVE_FORMAT_ADPCM with the specified filter, this flag is set. |
| ACMDRIVERDETAILS_SUPPORTF_CONVERTER | Driver supports conversion between two different formats of the same format tag while using the specified filter. For example, if a driver supports resampling of WAVE_FORMAT_PCM with the specified filter, this flag is set. |
| ACMDRIVERDETAILS_SUPPORTF_FILTER | Driver supports a filter (modification of the data without changing any of the format attributes). For example, if a driver supports volume or echo operations on WAVE_FORMAT_PCM, this flag is set. |
| ACMDRIVERDETAILS_SUPPORTF_HARDWARE | Driver supports hardware input, output, or both with the specified filter through a waveform-audio device. An application should use the acmMetrics function with the ACM_METRIC_HARDWARE_WAVE_INPUT and ACM_METRIC_HARDWARE_WAVE_OUTPUT metric indices to get the waveform-audio device identifiers associated with the supporting ACM driver. |
Return value
The callback function must return TRUE to continue enumeration or FALSE to stop enumeration.
Remarks
The acmFilterEnum function will return MMSYSERR_NOERROR (zero) if no filters are to be enumerated. 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 |