jpegtorgb.h

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/* JPEG To RGB interface --Raphael Grasset - 04/07/16 - 2004 Hitlab NZ. All Rights reserved--

This file define simple routine functions for  converting a JPEG image to RGB format.
It use is ONLY for EyeToy Camera.

WARNING : It use a static image area : at each call of conversion, the new
image is copying on the same memory area (limited dynamic allocation mamagement).
So be careful when you manipulating the pointer on the image !!

USAGE :
Based on libjpeg (providing hardware decompression), you need just add few things on your code:

#include "jpegtorgb.h" //this file

int xsiwe=640;//video image format
int ysize=480;//video image format
....
JPEGToRGBInit(xsize,ysize); //init function with image size in parameters
....

ARUint8* decompressed_image=JPEGToRGB(video_image,xsize,ysize); //converting function (converted image return)

don't be care with ARUint8, equivalent to an unsigned char format.

*/

#include "jpeglib.h"
#include "jerror.h"
#include <setjmp.h>


/*---------------- Direct Input Functions for libjpeg  --------------*/

/* we overload the interface for open a jpeg file : the libjpeg
file is limited for only FILE* input. Since we have a JPEG image
in memory we need a new interface for libjpeg. For these we overload
differents functions.
I have modified the code for jpeg_stdio_src, and providing
new functions name EyeToy_XXX (XXX template

Need to be optimized, cleaned.
*/

#define JFREAD(file,buf,sizeofbuf)  \
  ((size_t) fread((void *) (buf), (size_t) 1, (size_t) (sizeofbuf), (file)))

/* Expanded data source object for stdio input */

typedef struct {
  struct jpeg_source_mgr pub;   /* public fields */

  unsigned char* image;
  int image_size;
  JOCTET * buffer;              /* start of buffer */
  boolean start_of_file;        /* have we gotten any data yet? */
} my_source_mgr;

typedef my_source_mgr * my_src_ptr;

#define INPUT_BUF_SIZE  4096    /* choose an efficiently fread'able size */

/*
 * Initialize source --- called by jpeg_read_header
 * before any data is actually read.
 */

METHODDEF(void)
EyeToy_init_source (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;

  /* We reset the empty-input-file flag for each image,
   * but we don't clear the input buffer.
   * This is correct behavior for reading a series of images from one source.
   */
  src->start_of_file = TRUE;
}

/*
 * Fill the input buffer --- called whenever buffer is emptied.
 *
 * In typical applications, this should read fresh data into the buffer
 * (ignoring the current state of next_input_byte & bytes_in_buffer),
 * reset the pointer & count to the start of the buffer, and return TRUE
 * indicating that the buffer has been reloaded.  It is not necessary to
 * fill the buffer entirely, only to obtain at least one more byte.
 *
 * There is no such thing as an EOF return.  If the end of the file has been
 * reached, the routine has a choice of ERREXIT() or inserting fake data into
 * the buffer.  In most cases, generating a warning message and inserting a
 * fake EOI marker is the best course of action --- this will allow the
 * decompressor to output however much of the image is there.  However,
 * the resulting error message is misleading if the real problem is an empty
 * input file, so we handle that case specially.
 *
 * In applications that need to be able to suspend compression due to input
 * not being available yet, a FALSE return indicates that no more data can be
 * obtained right now, but more may be forthcoming later.  In this situation,
 * the decompressor will return to its caller (with an indication of the
 * number of scanlines it has read, if any).  The application should resume
 * decompression after it has loaded more data into the input buffer.  Note
 * that there are substantial restrictions on the use of suspension --- see
 * the documentation.
 *
 * When suspending, the decompressor will back up to a convenient restart point
 * (typically the start of the current MCU). next_input_byte & bytes_in_buffer
 * indicate where the restart point will be if the current call returns FALSE.
 * Data beyond this point must be rescanned after resumption, so move it to
 * the front of the buffer rather than discarding it.
 */

METHODDEF(boolean)
EyeToy_fill_input_buffer (j_decompress_ptr cinfo)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;

  src->pub.next_input_byte = src->image;
  src->pub.bytes_in_buffer = src->image_size;
  
  src->start_of_file = FALSE;

  return TRUE;
}

/*
 * Skip data --- used to skip over a potentially large amount of
 * uninteresting data (such as an APPn marker).
 *
 * Writers of suspendable-input applications must note that skip_input_data
 * is not granted the right to give a suspension return.  If the skip extends
 * beyond the data currently in the buffer, the buffer can be marked empty so
 * that the next read will cause a fill_input_buffer call that can suspend.
 * Arranging for additional bytes to be discarded before reloading the input
 * buffer is the application writer's problem.
 */

METHODDEF(void)
EyeToy_skip_input_data (j_decompress_ptr cinfo, long num_bytes)
{
  my_src_ptr src = (my_src_ptr) cinfo->src;

  /* Just a dumb implementation for now.  Could use fseek() except
   * it doesn't work on pipes.  Not clear that being smart is worth
   * any trouble anyway --- large skips are infrequent.
   */
  if (num_bytes > 0) {
    while (num_bytes > (long) src->pub.bytes_in_buffer) {
      num_bytes -= (long) src->pub.bytes_in_buffer;
      (void) EyeToy_fill_input_buffer(cinfo);
      /* note we assume that fill_input_buffer will never return FALSE,
       * so suspension need not be handled.
       */
    }
    src->pub.next_input_byte += (size_t) num_bytes;
    src->pub.bytes_in_buffer -= (size_t) num_bytes;
  }
}

/*
 * An additional method that can be provided by data source modules is the
 * resync_to_restart method for error recovery in the presence of RST markers.
 * For the moment, this source module just uses the default resync method
 * provided by the JPEG library.  That method assumes that no backtracking
 * is possible.
 */

/*
 * Terminate source --- called by jpeg_finish_decompress
 * after all data has been read.  Often a no-op.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */

METHODDEF(void)
EyeToy_term_source (j_decompress_ptr cinfo)
{
  /* no work necessary here */
}


/*
The new jpeg access function : directly read the memory
buffer instead of a FILE* input. Since all the image
is in memory we put all the buffer in one pass.
*/

GLOBAL(void)
EyeToy_jpeg_stdio_src(j_decompress_ptr cinfo,unsigned char *image,int count)
{
  my_src_ptr src;

  /* The source object and input buffer are made permanent so that a series
   * of JPEG images can be read from the same file by calling jpeg_stdio_src
   * only before the first one.  (If we discarded the buffer at the end of
   * one image, we'd likely lose the start of the next one.)
   * This makes it unsafe to use this manager and a different source
   * manager serially with the same JPEG object.  Caveat programmer.
   */
  if (cinfo->src == NULL) {     /* first time for this JPEG object? */
    cinfo->src = (struct jpeg_source_mgr *)(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_PERMANENT,
    sizeof(my_source_mgr));
    src = (my_src_ptr) cinfo->src;
    src->buffer = (JOCTET *)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, INPUT_BUF_SIZE * sizeof(JOCTET));
  }

  src = (my_src_ptr) cinfo->src;
  src->pub.init_source = EyeToy_init_source;
  src->pub.fill_input_buffer = EyeToy_fill_input_buffer;
  src->pub.skip_input_data = EyeToy_skip_input_data;
  src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */
  src->pub.term_source = EyeToy_term_source;
  src->image=image;
  src->image_size=count;
  src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */
  src->pub.next_input_byte = NULL; /* until buffer loaded */
}

static ARUint8* TransfertBufferImage;

/*---------------- Main Functions --------------*/

void JPEGToRGBInit(int xsize,int ysize)
{
  TransfertBufferImage = malloc(xsize*ysize*3);  
}
 
 
ARUint8* JPEGToRGB(ARUint8* image, int xsize,int ysize)
{

  int image_height=xsize;       /* Number of rows in image */
  int image_width=ysize;                /* Number of columns in image */

  struct jpeg_error_mgr jerr;
  struct jpeg_decompress_struct cinfo;

  JSAMPROW row_pointer[1];      /* pointer to JSAMPLE row[s] */
  int row_stride;               /* physical row width in output buffer */
  int crows=0;

  cinfo.err = jpeg_std_error(&jerr);

  jpeg_create_decompress(&cinfo);

   ssize_t count;
   count=(image[0]+image[1]*65536)/8;

   EyeToy_jpeg_stdio_src(&cinfo,image+2,count);

  (void) jpeg_read_header(&cinfo, TRUE);

  (void) jpeg_start_decompress(&cinfo);

  row_stride = cinfo.output_width * cinfo.output_components;
  /* Make a one-row-high sample array that will go away when done with image */
  
  while (cinfo.output_scanline < cinfo.output_height) 
  {
    row_pointer[0] = & TransfertBufferImage[crows * row_stride];
    (void) jpeg_read_scanlines(&cinfo, row_pointer, 1);    
    crows++;
  }

  (void) jpeg_finish_decompress(&cinfo);

  jpeg_destroy_decompress(&cinfo);

  return TransfertBufferImage;
}