LFile::GetExtensionAudio

#include "ltwrappr.h"

virtual L_INT LFile::GetExtensionAudio(pExtensionList, nStream, ppBuffer, puSize)

pEXTENSIONLIST pExtensionList;	/* pointer to a structure */
L_INT nStream;	/* audio stream index */
L_UCHAR ** ppBuffer;	/* pointer to a pointer */
L_SIZE_T *puSize;	/* pointer to a variable to be updated */

Gets the embedded audio data from the specified extension list.

Parameter	Description
pExtensionList	Pointer to the EXTENSIONLIST structure that contains the audio data to get.
nStream	Index of the audio stream to retrieve. The extensions may have more than one audio stream. This index is 0-based. Therefore, the first stream is stream 0, the second stream is stream 1, etc. To retrieve all the audio streams, retrieve the streams one by one until an error is returned.
ppBuffer	Pointer to be updated with a pointer to the retrieved audio data. This pointer will point into the pExtensionList. Therefore, this pointer will be valid as long as pExtensionList is valid. The memory will be freed when LFile::FreeExtensions is called, so do not try to free this memory.
puSize	Pointer to a variable to be updated with the size of the audio data.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

The audio data is stored inside extensions in the WAVE format. The audio data can be played directly from memory, or the data can be written to a disk file and played from the disk. When writing the audio data to a disk file, give the file a .WAV extension.

Required DLLs and Libraries

LTFIL
Exif file format DLLs

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

See Also

Functions:	LFile::ReadFileExtensions, LFile::LoadExtensionStamp, LFile::FreeExtensions, Class Members
Topics:	Raster Image Functions: Getting and Setting File Information
	Exif File Extensions
	Implementing Exif Features

Example

#include <stdio.h>
L_INT LFile__GetExtensionAudioExample(L_TCHAR * pszFile, L_TCHAR * pszAudioFile)
{
   L_INT nRet;
   LFile File;
   pEXTENSIONLIST pExtensionList;
   DWORD wWriteByte;
   File.SetFileName(pszFile);
   nRet = File.ReadFileExtensions(&pExtensionList);
   if(nRet != SUCCESS)
   {
      MessageBox(NULL, TEXT("Error getting extensions!"), TEXT("Testing"), MB_OK);
      return nRet;
   }
   
   if (pExtensionList->uFlags & EXTENSION_AUDIO)
   {
      L_UCHAR * pData;
      L_SIZE_T uSize;
      nRet = File.GetExtensionAudio (pExtensionList, 0, &pData, &uSize);
      if(nRet != SUCCESS)
      {
         MessageBox(NULL, TEXT("Error getting the audio data!"), TEXT("Testing"), MB_OK);
         return nRet;
      }
      else
      {
         HANDLE fd;
         fd = CreateFile(pszAudioFile, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, 0); // pszAudioFile: .wav file
         if (fd)
         {
            WriteFile(fd, pData, (DWORD) uSize, &wWriteByte, NULL);
            CloseHandle(fd);
         }
      }
   }
   nRet = File.FreeExtensions(pExtensionList);
   if(nRet != SUCCESS)
      return nRet;
   return SUCCESS;
}