ACMDM_FORMATTAG

ACMDM_FORMATTAG_DETAILS

See also ACMDM_FORMAT_DETAILS, ACMDM_FORMAT_SUGGEST, ACMDRVFORMATSUGGEST

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

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

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

ACMERR_NOTPOSSIBLE	The ACMFORMATTAGDETAILS 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 the specified query operation.

lParam1

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

lParam2

Flags for getting the format tag details. This parameter is identical to the fdwDetails parameter passed to acmFormatTagDetails.

ACM_FORMATTAGDETAILSF_INDEX	Indicates that a format tag index was given in the dwFormatTagIndex member of the ACMFORMATTAGDETAILS structure. The format tag and details must be returned in the structure specified by lParam1. The index ranges from zero to one less than the cFormatTags member returned in the ACMDRIVERDETAILS structure for this driver.
ACM_FORMATTAGDETAILSF_FORMATTAG	Indicates that a format tag was given in the dwFormatTag member of the ACMFORMATTAGDETAILS structure. The format tag details must be returned in the structure specified by lParam1.
ACM_FORMATTAGDETAILSF_LARGESTSIZE	Indicates that the details on the format tag with the largest format size, in bytes, must be returned. The dwFormatTag member will either be WAVE_FORMAT_UNKNOWN or the format tag to find the largest size for.

An ACM driver must support this message. Note that the following parameters for the ACMDM_FORMATTAG_DETAILS message will be validated before calling the driver:

The lParam1 parameter will contain a valid pointer to an ACMFORMATTAGDETAILS structure with the proper members initialized for the requested query operation. This structure will be at least the size of the base ACMFORMATTAGDETAILS structure.
The cbStruct member of the ACMFORMATTAGDETAILS structure will be set to at least the size, in bytes, of the base ACMFORMATTAGDETAILS 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 format tag, the cbStruct member of the ACMFORMATTAGDETAILS 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 ACMFORMATTAGDETAILS structure.

Note that an ACM driver should not return a name in the szFormatTag member of the ACMFORMATTAGDETAILS structure for WAVE_FORMAT_PCM formats; the ACM will provide the proper localized name for the driver.