ACMFILTERENUMCBA callback function (msacm.h)
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
ACMFILTERENUMCBA Acmfilterenumcba;
BOOL Acmfilterenumcba(
HACMDRIVERID hadid,
LPACMFILTERDETAILSA 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.
Note
The msacm.h header defines ACMFILTERENUMCB as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
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 |