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This message requests an ACM driver to return information about a format associated with a specified format tag.
Parameters
Value | Description |
---|---|
ACM_FORMATDETAILSF_INDEX | Indicates that the dwFormatIndexmember of ACMFORMATDETAILScontains a format index. The valid index range is from 0 through 1 less than the cStandardFormatsmember returned in ACMFORMATTAGDETAILSfor the format tag. |
ACM_FORMATDETAILSF_FORMAT | Indicates that the client has filled in the WAVEFORMATEXstructure associated with ACMFORMATDETAILS. |
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.
Remarks
The ACM 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 acmFormatDetailsfunction.
All ACM drivers must support this message.
The client can perform either of the following actions:
The client specifies the format tag in the dwFormatTagmember of ACMFORMATDETAILS. The driver returns the following information for a particular format belonging to the format tag:
Before calling the driver's ACM_IOControlfunction, the ACM verifies the following conditions:
The WAVEFORMATEXstructure is a generic structure for describing a waveform format. Generally, use this structure as a basis for defining structures for your specific format types, as in the IMA ADPCM audio codec. For an example, see the IMAADPCMWAVEFORMATstructure in the Mmreg.h header file. When a client sends an ACMDM_FORMAT_DETAILS message, it specifies the address of a structure that you have defined for the specified format type. This structure typically is larger than the generic WAVEFORMATEXstructure.
Before returning, the driver must set the cbStructmember of ACMFORMATDETAILSto the actual number of bytes returned. The value returned in cbStructmust not be greater than the value received.
The szFormatmember of WAVEFORMATEXis used for returning a format description string. If an ACM driver returns a 0-length string in szFormat, the ACM creates an internationalized description string for the format. This string includes the format's speed, in Hz; bit depth; and channel setting, mono or stereo; based on the contents of the nSamplesPerSec, wBitsPerSample, and nChannelsmembers of WAVEFORMATEX. If wBitsPerSamplecontains 0, the ACM does not include the bit depth in the description string. You can provide your own description string and return it in szFormat, but it is best to enable the ACM to generate an internationalized description.
For more information about format and filter tags and format and filter structures, see the Windows NT DDK.
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
Last updated on Tuesday, July 13, 2004