LJp2FileFormat::ExtractFramesBuffer (original) (raw)

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

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.

See Also

Functions

• LJp2FileFormat::ExtractFrames
• LJp2FileFormat::ExtractFramesBufferMemory
• LJp2FileFormat::AppendFrames
• LJp2FileFormat::AppendGMLData
• LJp2FileFormat::ReadBox
• LJp2FileFormat::ReadGMLData
• LJp2FileFormat::ReadFrames
• LJp2FileFormat::FragmentJpxFile

Topics

• Implementing JPEG 2000 Features
• Raster Image Functions: Working with JPEG 2000
• Programming with JPX Features
• JPX File Comments
• Raster Image Functions: Working with JPX

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; }

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