CreatePipe and a Callback

Hello all;

I want to know if I can use a pipe between my application and a callback function.
The examples that I find all create a thread. So I am wondering since a callback is basically it's own thread, why cant I pipe the output of the callback back to my application.

Also I can not use a named pipe. Because I want my application to be backwards compatible with Windows 98. Windows 98 does not support named pipes.

Here is the code I have so far. The code compiles clean but in the callback function I get an error message of "invalid handle" from the WriteFile.

Any ideals/clues/points apreciated!
RJ

#include <windows.h>
#include <assert.h>
#include <stdio.h>
#include <conio.h>
#include "madlldlib.h"


// Structure which encapsulates the data to be transferred from the
// writer thread to the reader thread.
struct ThreadData {
      HANDLE hWrThread;
      HANDLE hRdThread;
}thdData;


int twentyfour = 24;
unsigned long pbuffsz = 256+twentyfour;


/*
 * The callback function is used for reporting purposes and
 * garnering information about the source MP3 file. This callback
 * simply prints information to STDOUT, but it usually would be
 * used to increment a counter, calculate a percentage, or advance
 * a status bar.
 */

void __stdcall mycb (unsigned long fcnt, unsigned long bcnt, struct mad_header *mhdr)
{

      char pmsg[256];
      unsigned long bamt = 0;
      
      //thdData.hWrThread = GetCurrentThread(); //this side writes

      /*
       * If this is the first iteration (frame count is one)
       * then print out the MP3 layer information. Using this logic
       * one can retrieve information about the MP3 file, such as
       * channels, layer, etc., that might be useful to the calling
       * code.
       */      

      printf("\nIn mycb\n");
      getch();

      if (fcnt == 1) {
            

            sprintf(pmsg, "fc=%d,tb=%d,lyr=%d,md=%d,mdx=%d,emp=%d,br=%d,sr=%d",
                        fcnt,
                        bcnt,
                        mhdr->layer,
                        mhdr->mode,
                        mhdr->mode_extension,
                        mhdr->emphasis,
                        mhdr->bitrate,
                        mhdr->samplerate);


            if (WriteFile(thdData.hWrThread, &pmsg, 256, &bamt, NULL) == 0)
            {
            DWORD err=GetLastError();
             LPVOID lpMsgBuf;
            FormatMessage(
            FORMAT_MESSAGE_ALLOCATE_BUFFER |
            FORMAT_MESSAGE_FROM_SYSTEM |
            FORMAT_MESSAGE_IGNORE_INSERTS,
            NULL,
            err,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
            (LPTSTR) &lpMsgBuf,
            0,
            NULL
            );
            // Process any inserts in lpMsgBuf.
            // ...
            // Display the string.
            printf("\nFnct==1 %s %ld\n",(LPCTSTR)lpMsgBuf, err);
            // Free the buffer.
            LocalFree( lpMsgBuf );
              return;            
            }//endif


      }
      else {
            
            sprintf(pmsg, "fc=%d,tb=%d", fcnt, bcnt);

            if (WriteFile(thdData.hWrThread, &pmsg, 256, &bamt, NULL) == 0)
            {
            DWORD err=GetLastError();
             LPVOID lpMsgBuf;
            FormatMessage(
            FORMAT_MESSAGE_ALLOCATE_BUFFER |
            FORMAT_MESSAGE_FROM_SYSTEM |
            FORMAT_MESSAGE_IGNORE_INSERTS,
            NULL,
            err,
            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
            (LPTSTR) &lpMsgBuf,
            0,
            NULL
            );
            // Process any inserts in lpMsgBuf.
            // ...
            // Display the string.
            printf("\nElse->%s %ld\n",(LPCTSTR)lpMsgBuf, err);
            // Free the buffer.
            LocalFree( lpMsgBuf );
              return;            

            }//endif            


      }//endelse

      printf("\nat end of mycb\n");
      getch();
      
}//endcallbackfunc


int main(int argc, char *argv[])
{

      DWORD dwRead;
      BOOL    bReturn = FALSE;            
      char statmsg[256];
      int status;
      
      argc=4;
      argv[0]="armslen";
      argv[1]="piano.mp3";
      argv[2]="test.wav";
      argv[3]="wav";

      
      if (argc != 4) {
            printf("\nusage: %s 'input.mp3' 'output file' 'pcm|wav'\n", argv[0]);
            return 1;
      }

      
      // Creates an anonymous pipe.
      bReturn = CreatePipe(&thdData.hRdThread,&thdData.hWrThread,
            NULL,sizeof(pbuffsz));
      
      if (bReturn != FALSE)
      {
            printf("CreatePipe worked");
            getch();

            thdData.hRdThread = GetCurrentThread(); //this side reads

            //Call function here
            if (strcmp(argv[3], "pcm")==0) {            
            status = CbMpegAudioDecoder(argv[1], argv[2], 0, statmsg, mycb);
            }
            else {                                                      
            status = CbMpegAudioDecoder(argv[1], argv[2], 1, statmsg, mycb);
            }


            if(statmsg)
            {
                  printf("\n%s\n",statmsg);
                  printf("\nError in calling library function\n");
                  return 1;

            }//endif

            printf("Call to lib worked");
            getch();

            char c=-1;
            while (c != '\0')
            {

        ReadFile(thdData.hRdThread, &c, 1, &dwRead, NULL);

        if (dwRead > 0 && c != 0) putchar(c);
            }

          
      }//endif!False
      else
      {
            printf("\nError in createpipe\n");
            return 1;
      }

return 0;

}//endmain