acmStreamSize

The acmStreamSize function returns a recommended size for a source or destination buffer on an ACM stream.

MMRESULT acmStreamSize(
  HACMSTREAM has,          
  DWORD cbInput,           
  LPDWORD pdwOutputBytes,  
  DWORD fdwSize            
);

Parameters

has
Handle of the conversion stream.
cbInput
Size, in bytes, of the source or destination buffer. The fdwSize flags specify what the input parameter defines. This parameter must be nonzero.
pdwOutputBytes
Address of a variable that contains the size, in bytes, of the source or destination buffer. The fdwSize flags specify what the output parameter defines. If the acmStreamSize function succeeds, this location will always be filled with a nonzero value.
fdwSize
Flags for the stream size query. The following values are defined:
ACM_STREAMSIZEF_DESTINATION
The cbInput parameter contains the size of the destination buffer. The pdwOutputBytes parameter will receive the recommended source buffer size, in bytes.
ACM_STREAMSIZEF_SOURCE
The cbInput parameter contains the size of the source buffer. The pdwOutputBytes parameter will receive the recommended destination buffer size, in bytes.

Return Values

Returns zero if successful or an error otherwise. Possible error values include the following:

Value Description
ACMERR_NOTPOSSIBLE The requested operation cannot be performed.
MMSYSERR_INVALFLAG At least one flag is invalid.
MMSYSERR_INVALHANDLE The specified handle is invalid.
MMSYSERR_INVALPARAM At least one parameter is invalid.

Remarks

An application can use this function to determine suggested buffer sizes for either source or destination buffers. The buffer sizes returned might be only an estimation of the actual sizes required for conversion. Because actual conversion sizes cannot always be determined without performing the conversion, the sizes returned will usually be overestimated.

In the event of an error, the location pointed to by pdwOutputBytes will receive zero. This assumes that the pointer specified by pdwOutputBytes is valid.

QuickInfo

  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in msacm.h.
  Import Library: Use msacm32.lib.

See Also

Audio Compression Manager Overview, Audio Compression Functions