ACMDM_FORMAT

ACMDM_FORMAT_SUGGEST

See also ACMDM_FORMAT_DETAILS, ACMDM_FORMATTAG_DETAILS, ACMDRVFORMATSUGGEST

lParam1 = (LPARAM) pacmDFS  // see below
lParam2 = reserved          // should be ignored

Sent to an Audio Compression Manager (ACM) driver to suggest a destination format for a given source format for a conversion. This message is usually sent to an ACM driver in response to an acmFormatSuggest call.

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

ACMERR_NOTPOSSIBLE	The ACMDRVFORMATSUGGEST structure and suggestion restrictions specify information that cannot be satisfied by the driver.
MMSYSERR_NOTENABLED	The driver failed to load or initialize.
MMSYSERR_NOTSUPPORTED	The driver does not support format suggestion operations.

lParam1

Address of the ACMDRVFORMATSUGGEST structure that defines how a destination format should be suggested, given a particular source format.

An ACM driver must support this message if it supports the ACMDM_STREAM_OPEN message and conversions other than filtering operations are available. Note that the following parameters for the ACMDM_FORMAT_SUGGEST message will be validated before calling the driver:

The lParam1 parameter will contain a valid pointer to an ACMDRVFORMATSUGGEST structure with all members initialized. This structure will be at least the size of the base ACMDRVFORMATSUGGEST structure.
The cbStruct member of the ACMDRVFORMATSUGGEST structure will be set to at least the size, in bytes, of the base ACMDRVFORMATSUGGEST structure.
The pwfxSrc member of the ACMDRVFORMATSUGGEST structure will be a valid pointer to a WAVEFORMATEX structure that is at least the size, in bytes, specified in the cbwfxSrc member of the ACMDRVFORMATSUGGEST structure.
The pwfxDst member of the ACMDRVFORMATSUGGEST structure will be a valid pointer to a WAVEFORMATEX structure that is at least the size, in bytes, specified in the cbwfxDst member of the ACMDRVFORMATSUGGEST structure.
No invalid flag combinations will be specified in lParam2.

The driver need not check for these conditions.