ACMFORMATTAGENUMCB 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
ACMFORMATTAGENUMCB Acmformattagenumcb;
BOOL Acmformattagenumcb(
HACMDRIVERID hadid,
LPACMFORMATTAGDETAILS 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.
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 |