ACMFILTERENUMCB callback function (msacm.h)

Article
08/16/2022

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