Retrieving a String That Describes a Filter

An application often needs to display a string that describes the current format. This task can be accomplished easily with the acmFilterTagDetails and acmFilterDetails functions. These functions must be called with the appropriate filter or filter tag. The following example shows how to use these functions.

#include <mmsystem.h>
#include <mmreg.h>
#include <msacm.h>

BOOL GetFilterDescription 
( 
    LPWAVEFILTER  pwfltr, 
    LPTSTR        pszFilterTag, 
    DWORD         cchFilterTag, // Size of pszFilterTag buffer.
    LPTSTR        pszFilter,
    DWORD         cchFilter     // Size of pszFilter buffer.

) 
{ 
    MMRESULT      mmr; 
    errno_t       errno;
 
    // Retrieve the name for the filter tag of the specified filter. 
    if (NULL != pszFilterTag) { 
        ACMFILTERTAGDETAILS aftd; 
 
        // Initialize all unused members of the ACMFILTERTAGDETAILS 
        // structure to zero. 
        memset(&aftd, 0, sizeof(aftd)); 
 
        // Fill in the required members of the ACMFILTERTAGDETAILS 
        // structure for the ACM_FILTERTAGDETAILSF_FILTERTAG query. 
        aftd.cbStruct = sizeof(aftd); 
        aftd.dwFilterTag = pwfltr->dwFilterTag; 
 
        // Ask the ACM to find the first available driver that 
        // supports the specified filter tag. 
        mmr = acmFilterTagDetails(NULL, &aftd, 
            ACM_FILTERTAGDETAILSF_FILTERTAG); 
        if (MMSYSERR_NOERROR != mmr) { 
            // No ACM driver is available that supports the 
            // specified filter tag. 
            return FALSE; 
        } 
 
        // Copy the filter tag name into the calling application's 
        // buffer. 

        errno = wcscpy_s(pszFilterTag, cchFilterTag, aftd.szFilterTag); 
        if (errno != 0)
        {
            return FALSE;
        }
    } 
 
    // Retrieve the description of the attributes for the specified 
    // filter. 
    if (NULL != pszFilter) { 
        ACMFILTERDETAILS afd; 
 
        // Initialize all unused members of the ACMFILTERDETAILS 
        // structure to zero. 
        memset(&afd, 0, sizeof(afd)); 
 
        // Fill in the required members of the ACMFILTERDETAILS 
        // structure for the ACM_FILTERDETAILSF_FILTER query. 
        afd.cbStruct    = sizeof(afd); 
        afd.dwFilterTag = pwfltr->dwFilterTag; 
        afd.pwfltr      = pwfltr; 
        afd.cbwfltr     = pwfltr->cbStruct; 
 
        // Ask the ACM to find the first available driver that 
        // supports the specified filter. 
        mmr = acmFilterDetails(NULL, &afd, ACM_FILTERDETAILSF_FILTER); 
        if (MMSYSERR_NOERROR != mmr) { 
            // No ACM driver is available that supports the 
            // specified filter. 
            return FALSE; 
        } 
 
        // Copy the description string into the caller's buffer. 
        errno = wcscpy_s(pszFilter, cchFilter, afd.szFilter); 
        if (errno != 0)
        {
            return FALSE;
        }
    } 
 
    return TRUE; 
}