acmFormatTagEnumCallback

The acmFormatTagEnumCallback function specifies a callback function used with the acmFormatTagEnum function. The acmFormatTagEnumCallback name is a placeholder for an application-defined function name.

BOOL ACMFORMATTAGENUMCB acmFormatTagEnumCallback(
  HACMDRIVERID hadid,           
  LPACMFORMATTAGDETAILS paftd,  
  DWORD dwInstance,             
  DWORD fdwSupport              
);
 

Parameters

hadid

Handle of the ACM driver identifier.

paftd

Address of 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 fdwSupport flags of the ACMDRIVERDETAILS structure. This parameter can be a combination of the following values and indicates which operations the driver supports with the format tag:

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 Values

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.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in msacm.h.
  Import Library: User-defined.
  Unicode: Defined as Unicode and ANSI prototypes.

See Also

Audio Compression Manager Overview, Audio Compression Functions, acmFormatTagEnum, ACMFORMATTAGDETAILS, ACMDRIVERDETAILS, acmMetrics, acmDriverAdd, acmDriverRemove, acmDriverPriority