ACMFORMATTAGENUMCBW callback function (msacm.h)
The acmFormatTagEnumCallback function specifies a callback function used with the acmFormatTagEnum function. The acmFormatTagEnumCallback name is a placeholder for an application-defined function name.
Syntax
ACMFORMATTAGENUMCBW Acmformattagenumcbw;
BOOL Acmformattagenumcbw(
HACMDRIVERID hadid,
LPACMFORMATTAGDETAILSW paftd,
DWORD_PTR dwInstance,
DWORD fdwSupport
)
{...}
Parameters
hadid
Handle to the ACM driver identifier.
paftd
Pointer to an ACMFORMATTAGDETAILS structure that contains the enumerated format tag details.
dwInstance
Application-defined value specified in the acmFormatTagEnum function.
fdwSupport
Driver-support flags specific to the format tag. These flags are identical to the ACMDRIVERDETAILS structure. This parameter can be a combination of the following values and indicates which operations the driver supports with the format 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 where one of the tags is the specified format tag. For example, if a driver supports compression from WAVE_FORMAT_PCM to WAVE_FORMAT_ADPCM, this flag is set. |
| ACMDRIVERDETAILS_SUPPORTF_CONVERTER | Driver supports conversion between two different formats of the specified format tag. For example, if a driver supports resampling of WAVE_FORMAT_PCM, 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 the specified format tag, this flag is set. |
| ACMDRIVERDETAILS_SUPPORTF_HARDWARE | Driver supports hardware input, output, or both of the specified format tag through a waveform-audio device. An application should use acmMetrics with the ACM_METRIC_HARDWARE_WAVE_INPUT and ACM_METRIC_HARDWARE_WAVE_OUTPUT metric indexes 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 acmFormatTagEnum function will return MMSYSERR_NOERROR (zero) if no format tags 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 ACMFORMATTAGENUMCB 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 |