jcmarker.c

这是一个JPEG编码源代码

#include <stdio.h>

#include "jinclude.h"
#include "jcint.h"

typedef enum {
  SOF0 = 0xC0 ,   /* basic dct */
  SOF1 = 0xC1 ,   /* extend dct */
  
  DHT  = 0xC4 ,   /* huffman table defination */

  SOI  = 0xD8 ,   /* start of image */
  EOI  = 0xD9 ,   /* end of image */
  SOS  = 0xDA ,   /* start of scan */
  DQT  = 0xDB ,   /* quant table defination */

  COM  = 0xDE     /* common */
} MARKER;

void 
jmkr_write_image_start(jpeg_compress_info *cinfo) 
{
  jutl_write_byte(0xFF, cinfo->output);
  jutl_write_byte(SOI, cinfo->output);
}

void 
jmkr_write_image_end  (jpeg_compress_info *cinfo)
{
  jutl_write_byte(0xFF, cinfo->output);
  jutl_write_byte(EOI, cinfo->output);
}

void jmkr_write_frame_head (jpeg_compress_info *cinfo)
{
  int i;
  UINT16 Lf, X, Y;
  UINT8  P, Nf, C, H, V, Tq;
  jutl_write_byte(0xFF, cinfo->output);
  jutl_write_byte(SOF0, cinfo->output);
  Nf = cinfo->num_comp;
  P  = cinfo->precision;
  X  = cinfo->image_width;
  Y  = cinfo->image_height;
  Lf = 8 + 3*Nf;
  jutl_write_byte(Lf>>8, cinfo->output);
  jutl_write_byte(Lf&0xFF, cinfo->output);
  jutl_write_byte(P, cinfo->output);
  jutl_write_byte(Y>>8, cinfo->output);
  jutl_write_byte(Y&0xFF, cinfo->output);
  jutl_write_byte(X>>8, cinfo->output);
  jutl_write_byte(X&0xFF, cinfo->output);
  jutl_write_byte(Nf, cinfo->output);
  for (i=0; i<Nf; i++) {
    C = cinfo->comp[i].comp_id;
    H = cinfo->comp[i].h_factor;
    V = cinfo->comp[i].v_factor;
    Tq= cinfo->comp[i].quant_tbl_no;
    jutl_write_byte(C, cinfo->output);
    jutl_write_byte(((H<<4)|V), cinfo->output);
    jutl_write_byte(Tq, cinfo->output);
  } 
}

void 
jmkr_write_scan_head  (jpeg_compress_info *cinfo) 
{
  int i;
  UINT16 Ls;
  UINT8  Ns, Ss, Se, Ah, Al, Cs, Td, Ta;
  jutl_write_byte(0xFF, cinfo->output);
  jutl_write_byte(SOS, cinfo->output);
  Ns = cinfo->num_comp;
  Ls = 6+2*Ns;
  Ss = 0;  /* const!!! not change. */
  Se = 63;
  Ah = Al = 0;
  jutl_write_byte(Ls>>8, cinfo->output);
  jutl_write_byte(Ls&0xFF, cinfo->output);
  jutl_write_byte(Ns, cinfo->output);
  for (i=0; i<Ns; i++) {
    Cs = cinfo->comp[i].comp_id;
    Td = cinfo->comp[i].dc_tbl_no;
    Ta = cinfo->comp[i].ac_tbl_no;
    jutl_write_byte(Cs, cinfo->output);
    jutl_write_byte((Td<<4|Ta), cinfo->output);
  }
  jutl_write_byte(Ss, cinfo->output);
  jutl_write_byte(Se, cinfo->output);
  jutl_write_byte(((Ah<<4)|Al), cinfo->output);
}

void 
jmkr_write_quant_table(jpeg_compress_info *cinfo)
{
  int i, j;
  for (i=0; i<NUM_QUANT_TBLS; i++) {
    if (!cinfo->quant_table[i])
      continue;
    /* marker */
    jutl_write_byte(0xFF, cinfo->output);
    jutl_write_byte(DQT, cinfo->output);
    /* length, always 43h */
    jutl_write_byte(0x00, cinfo->output);
    jutl_write_byte(0x43, cinfo->output);
    /* ouput Pq & Tq */
    jutl_write_byte(i&0xFF, cinfo->output);
    /* all element */
    for (j=0; j<DCTSIZE2; j++) {
      UINT8 Q = cinfo->quant_table[i]->quantval[j];
      jutl_write_byte(Q, cinfo->output);
    }
  }
}

void 
jmkr_write_huff_table (jpeg_compress_info *cinfo)
{
  int i, j, num_val;
  UINT16 Lh;
  /* output DC HUFFMAN CODE */
  for (i=0; i<NUM_HUFF_TBLS; i++) {
    num_val = 0;
    if (!cinfo->dc_huff_table[i])
      continue;
    /* marker */
    jutl_write_byte(0xFF, cinfo->output);
    jutl_write_byte(DHT, cinfo->output);
    for (j=1; j<=16; j++) {
      num_val += cinfo->dc_huff_table[i]->bits[j];
    }
    /* length, always 43h */
    Lh = 3 + 16 + num_val;
    jutl_write_byte(Lh>>8, cinfo->output);
    jutl_write_byte(Lh&0xFF, cinfo->output);
    /* output identify */
    jutl_write_byte(i, cinfo->output);
    /* output bits */
    for (j=1; j<=16; j++) {
      jutl_write_byte(cinfo->dc_huff_table[i]->bits[j], cinfo->output);
    }
    for (j=0; j<num_val; j++) {
      jutl_write_byte(cinfo->dc_huff_table[i]->huffval[j], cinfo->output);
    }
  }
  /* output AC HUFFMAN CODE */
  for (i=0; i<NUM_HUFF_TBLS; i++) {
    num_val = 0;
    if (!cinfo->ac_huff_table[i])
      continue;
    /* marker */
    jutl_write_byte(0xFF, cinfo->output);
    jutl_write_byte(DHT, cinfo->output);
    for (j=1; j<=16; j++) {
      num_val += cinfo->ac_huff_table[i]->bits[j];
    }
    /* length, always 43h */
    Lh = 3 + 16 + num_val;
    jutl_write_byte(Lh>>8, cinfo->output);
    jutl_write_byte(Lh&0xFF, cinfo->output);
    /* output identify */
    jutl_write_byte((0x10|i), cinfo->output);
    /* output bits */
    for (j=1; j<=16; j++) {
      jutl_write_byte(cinfo->ac_huff_table[i]->bits[j], cinfo->output);
    }
    for (j=0; j<num_val; j++) {
      jutl_write_byte(cinfo->ac_huff_table[i]->huffval[j], cinfo->output);
    }
  }
}

void 
jmkr_write_jfif(jpeg_compress_info *cinfo)
{
  static const UINT8 jfcode[] = {
    0xFF, 0xE0, 0x00, 0x10, 0x4A, 0x46, 0x49, 0x46, 
    0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x00, 0x01, 
    0x00, 0x00
  };
  int i;
  for (i=0; i<18; i++) {
    jutl_write_byte(jfcode[i], cinfo->output);
  }
}

void 
jmkr_write_dri(jpeg_compress_info *cinfo) 
{
  static const UINT8 code[] = {
    0xFF, 0xDD, 0x00, 0x04, 0x00, 0x01
  };
  int i;
  for (i=0; i<6; i++) {
    jutl_write_byte(code[i], cinfo->output);
  }
}


void 
jmkr_write_start(jpeg_compress_info *cinfo) 
{
  jmkr_write_image_start(cinfo);
  jmkr_write_jfif(cinfo);
  jmkr_write_quant_table(cinfo);
  jmkr_write_frame_head(cinfo);
  jmkr_write_huff_table(cinfo);
/*  jmkr_write_dri(cinfo);*/
  jmkr_write_scan_head(cinfo);
}

void 
jmkr_write_end(jpeg_compress_info *cinfo) 
{
  jmkr_write_image_end(cinfo);
}