The acmStreamConvertCallback function specifies an application-provided callback function to be used when the acmStreamOpen function specifies the CALLBACK_FUNCTION flag. The acmStreamConvertCallback name is a placeholder for an application-defined function name.

void CALLBACK acmStreamConvertCallback(
  HACMSTREAM has,    
  UINT uMsg,         
  DWORD dwInstance,  
  LPARAM lParam1,    
  LPARAM lParam2     



Handle to the ACM conversion stream associated with the callback function.


ACM conversion stream message. The following values are defined.

Value Meaning
MM_ACM_CLOSE ACM has successfully closed the conversion stream identified by has. The handle specified by has is no longer valid after receiving this message.
MM_ACM_DONE ACM has successfully converted the buffer identified by lParam1 (which is a pointer to the ACMSTREAMHEADER structure) for the stream handle identified by has.
MM_ACM_OPEN ACM has successfully opened the conversion stream identified by has.


User-instance data given as the dwInstance parameter of the acmStreamOpen function.


Message parameter.


Message parameter.

Return Values

This function does not return a value.


The following functions should not be called from within the callback function: acmDriverAdd, acmDriverRemove, and acmDriverPriority.


  Windows NT/2000/XP: Included in Windows NT 3.1 and later.
  Windows 95/98/Me: Included in Windows 95 and later.
  Header: Declared in Msacm.h.

See Also

Audio Compression Manager, Audio Compression Functions, acmStreamOpen, ACMSTREAMHEADER, acmDriverAdd, acmDriverRemove, acmDriverPriority