ACMDM_FILTERTAG

ACMDM_FILTERTAG_DETAILS

lParam1 = (LPARAM) pacmFTD            // see below
lParam2 = (LPARAM) fFilterTagDetails  // see below

Sent to an Audio Compression Manager (ACM) driver to request details about a filter tag. This message is usually sent to an ACM driver in response to an acmFilterTagDetails or acmFilterTagEnum call.

Return MMSYSERR_NOERROR if the operation is successful or an error value otherwise. The following errors are possible:

ACMERR_NOTPOSSIBLE	The ACMFILTERTAGDETAILS structure and query operation specify information that is not understood by the driver.
MMSYSERR_NOTENABLED	The driver failed to load or initialize.
MMSYSERR_NOTSUPPORTED	The driver does not support filter operations or the specified query operation.

lParam1

Address of the ACMFILTERTAGDETAILS structure that should be filled in with the filter tag details. The cbStruct member of the ACMFILTERTAGDETAILS structure will contain the desired size, in bytes, of the details that the driver should return for the filter tag.

lParam2

Flags for getting the filter tag details. This parameter is identical to the fdwDetails parameter passed to acmFilterTagDetails.

ACM_FILTERTAGDETAILSF_FILTERTAG	Indicates that a filter tag was given in the dwFilterTag member of the ACMFILTERTAGDETAILS structure. The filter tag details must be returned in the structure specified by lParam1.
ACM_FILTERTAGDETAILSF_INDEX	Indicates that a filter tag index was given in the dwFilterTagIndex member of the ACMFILTERTAGDETAILS structure. The filter tag and details must be returned in the structure specified by lParam1. The index ranges from zero to one less than the cFilterTags member returned in the ACMDRIVERDETAILS structure for this driver.
ACM_FILTERTAGDETAILSF_LARGESTSIZE	Indicates that the details on the filter tag with the largest filter size, in bytes, must be returned. The dwFilterTag member will either be WAVE_FILTER_UNKNOWN or the filter tag to find the largest size for.

An ACM driver must support this message if it supports filter operations. Note that the following parameters for the ACMDM_FILTERTAG_DETAILS message will be validated before calling the driver:

The lParam1 parameter will contain a valid pointer to an ACMFILTERTAGDETAILS structure with the proper members initialized for the requested query operation. This structure will be at least the size of the base ACMFILTERTAGDETAILS structure.
The cbStruct member of the ACMFILTERTAGDETAILS structure will be set to at least the size, in bytes, of the base ACMFILTERTAGDETAILS structure.
No invalid flag combinations will be specified in lParam2.

The driver does not need to check for these conditions.

To enable the driver to successfully query for the filter tag, the cbStruct member of the ACMFILTERTAGDETAILS structure should be set to the actual size, in bytes, of the details being returned. This size cannot exceed the requested size. Note that the smallest possible size is the size of the base ACMFILTERTAGDETAILS structure.