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LJp2FileFormat::ExtractFramesBuffer

Summary

Extracts the frames that are specified by puFrames from the input file and save them into a new JPEG 2000 file in a memory buffer that is allocated by the function contains only the extracted frames headers and codestreams directly not through decompressing/compressing process.

Syntax

#include "ltwrappr.h"

L_INT LJp2FileFormat::ExtractFramesBuffer(pInFileName, lpBuffer, puBufferSize, puFrames, uNumOfFrames)

Parameters

L_TCHAR * pInFileName

Character string that contains the name of the JPEG 2000 file to extract frames from it.

L_UCHAR ** lpBuffer

Pointer to a pointer to be updated with an array of bytes that contains a JPEG 2000 file with extracted frames only. You must free this buffer by calling the Windows LocalFree() function.

L_SIZE_T * puBufferSize

Address of a variable to be updated with the size of the memory buffer in bytes.

L_UINT32 * puFrames

Array of unsigned integers specifies the indices of the frames to be extracted from the input JPEG 2000 file. All indices shall be 0-based. If any frames index is out the frames number the function will return ERROR_INV_PARAMETER.

L_UINT32 uNumOfFrames

Number of frames to be extracted. This field specifies the size of puFrames array.

Returns

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

Comments

LJp2FileFormat::ExtractFramesBuffer extracts the specified frames from the input file and save them into a new JPEG 2000 file in a memory buffer that is allocated by the function contains only the extracted frames headers and codestreams directly not through decompressing/compressing process so it saves processor time and memory. This function is very suitable to server application where multiple clients request specific frames of a JPEG 2000 file so instead of decompressing then compressing the frames this function copies only the needed frames data to generate them and saves the data into a new JPEG 2000 file in a memory buffer.

Required DLLs and Libraries

LTJP2
LFJ2K
LTIMGEFX
For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Platforms

Win32, x64.

Example

This example extracts a frame from JPX file.

L_INT LJp2FileFormat__ExtractFramesBufferExample(L_UINT8** lpOutBuffer, L_SIZE_T * puSize) 
{ 
   LJp2FileFormat Engine; 
   L_JP2_FILEINFO Jp2FileInfo; 
   L_UINT32 puFrames[1]; 
   L_INT nRet = 0; 
    
   *lpOutBuffer = NULL; 
   *puSize = 0; 
 
   Jp2FileInfo.uStructSize = sizeof(L_JP2_FILEINFO); 
   nRet = Engine.GetFileInfo(MAKE_IMAGE_PATH(TEXT("image1.jpx")),&Jp2FileInfo); 
   if(nRet != SUCCESS) 
      return nRet; 
    
   if(Jp2FileInfo.uNumOfFrames < 2) 
      return 0; 
 
   /*Extract the second frame*/ 
   puFrames[0] = 1; 
 
   nRet = Engine.ExtractFramesBuffer(MAKE_IMAGE_PATH(TEXT("image1.jpx")), lpOutBuffer, puSize, puFrames, 1); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   /*Free File Info structure*/ 
   nRet = Engine.FreeFileInfo( &Jp2FileInfo); 
    if(nRet != SUCCESS) 
      return nRet; 
    
   return SUCCESS; 
}