Microsoft Windows CE 3.0  

ACMDM_FORMAT_SUGGEST

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This message requests an ACM driver to choose a preferred destination format for a conversion with a specified source format.

Parameters

dwDriverID
Specifies a driver instance identifier. The driver returns this value in response to the ACM_Openfunction.
hDriver
Handle to a driver.
uMsg
Specifies this message.
lParam1
Pointer to an ACMDRVFORMATSUGGESTstructure declared in the Msacmdrv.h header file.
lParam2
Not used.

Return Values

MMSYSERR_NOERROR indicates success. Otherwise, the driver returns one of the MMSYSERR error values declared in the Mmsystem.h header file or one of the ACMERR error values declared in the Msacm.h header file. The following are possible error values:

MMSYSERR_NOTSUPPORTED
The driver does not support format suggestion operations.
ACMERR_NOTPOSSIBLE
The driver cannot suggest a destination format, based on the specified source format and restriction flags.

Remarks

The ACM (Waveapi.dll) sends this message by calling the ACM driver's ACM_IOControlentry point through the DeviceIoControlfunction. The ACM sends this message when an application calls the acmFormatSuggestfunction.

All ACM drivers that provide stream conversions must support this message.

ACMDRVFORMATSUGGESTcontains pointers to two WAVEFORMATEXstructures. One of these structures describes the client-specified source format. The other structure is used by the driver to return a suggested destination format. The client might specify values for some of the destination structure members in order to restrict the possible suggestions.

Given the specified source format and destination restrictions, if any, the driver determines if it can provide a conversion from the specified source format to a particular destination format. If it can, it returns a description of that format in the destination WAVEFORMATEXstructure.

Before calling the driver's ACM_IOControlfunction, the ACM should verify the following conditions:

  • The flag values contained in ACMDRVFORMATSUGGESTare valid.
  • The WAVEFORMATEXstructure containing the source format description is readable.
  • The WAVEFORMATEXstructure specified for receiving the suggested destination format description is writable.
  • The destination WAVEFORMATEXstructure's size, contained in the cbwfxDstmember of ACMDRVFORMATSUGGEST, is large enough to receive a format structure for an appropriate destination format.

    Requirements

    Runs on Versions Defined in Include Link to
    Windows CE OS 1.0 and later      
    Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

    See Also

    ACMDRVFORMATSUGGEST



     Last updated on Tuesday, July 13, 2004

    © 2004 Microsoft Corporation. All rights reserved.