dither.c

文件内包含H.263视频编码算法和解码算法2个文件

/************************************************************************
 *
 *  dither.c, pseudo colour dithering for tmndecode (H.263 decoder)
 */

#ifdef DISPLAY

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include "config.h"
#include "tmndec.h"
#include "global.h"

extern unsigned char pixel[256];

static unsigned char ytab[16 * (256 + 16)];
static unsigned char uvtab[256 * 269 + 270];

/****************************************************************************

  4x4 ordered dither

  Threshold pattern:

     0  8  2 10
    12  4 14  6
     3 11  1  9
    15  7 13  5
 
 ****************************************************************************/
void
ord4x4_dither_init (void)
{
  int i, j, v;
  unsigned char ctab[256 + 32];

  for (i = 0; i < 256 + 16; i++)
    {
      v = (i - 8) >> 4;
      if (v < 2)
        v = 2;
      else if (v > 14)
        v = 14;
      for (j = 0; j < 16; j++)
        ytab[16 * i + j] = pixel[(v << 4) + j];
    }

  for (i = 0; i < 256 + 32; i++)
    {
      v = (i + 48 - 128) >> 5;
      if (v < 0)
        v = 0;
      else if (v > 3)
        v = 3;
      ctab[i] = v;
    }

  for (i = 0; i < 255 + 15; i++)
    for (j = 0; j < 255 + 15; j++)
      uvtab[256 * i + j] = (ctab[i + 16] << 6) | (ctab[j + 16] << 4) | (ctab[i] << 2) | ctab[j];
}



void
ord4x4_dither_frame (unsigned char *src[], unsigned char *dst)
{
  int i, j;
  unsigned char *py = src[0];
  unsigned char *pu = src[1];
  unsigned char *pv = src[2];

  int width, height, cwidth;

  if (expand)
    {
      width = 2 * coded_picture_width;
      height = 2 * coded_picture_height;
      cwidth = 2 * chrom_width;
    }
  else
    {
      width = coded_picture_width;
      height = coded_picture_height;
      cwidth = chrom_width;
    }

  for (j = 0; j < height; j += 4)
    {
      register unsigned int uv;

      /* line j + 0 */
      for (i = 0; i < width; i += 8)
        {
          uv = uvtab[(*pu++ << 8) | *pv++];
          *dst++ = ytab[((*py++) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 8) << 4) | (uv >> 4)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 1028];
          *dst++ = ytab[((*py++ + 2) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 10) << 4) | (uv >> 4)];
          uv = uvtab[(*pu++ << 8) | *pv++];
          *dst++ = ytab[((*py++) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 8) << 4) | (uv >> 4)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 1028];
          *dst++ = ytab[((*py++ + 2) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 10) << 4) | (uv >> 4)];
        }

      pu -= cwidth;
      pv -= cwidth;

      /* line j + 1 */
      for (i = 0; i < width; i += 8)
        {
          uv = uvtab[((*pu++ << 8) | *pv++) + 2056];
          *dst++ = ytab[((*py++ + 12) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 4) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 3084];
          *dst++ = ytab[((*py++ + 14) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 6) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 2056];
          *dst++ = ytab[((*py++ + 12) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 4) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 3084];
          *dst++ = ytab[((*py++ + 14) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 6) << 4) | (uv & 15)];
        }

      /* line j + 2 */
      for (i = 0; i < width; i += 8)
        {
          uv = uvtab[((*pu++ << 8) | *pv++) + 1542];
          *dst++ = ytab[((*py++ + 3) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 11) << 4) | (uv >> 4)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 514];
          *dst++ = ytab[((*py++ + 1) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 9) << 4) | (uv >> 4)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 1542];
          *dst++ = ytab[((*py++ + 3) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 11) << 4) | (uv >> 4)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 514];
          *dst++ = ytab[((*py++ + 1) << 4) | (uv & 15)];
          *dst++ = ytab[((*py++ + 9) << 4) | (uv >> 4)];
        }

      pu -= cwidth;
      pv -= cwidth;

      /* line j + 3 */
      for (i = 0; i < width; i += 8)
        {
          uv = uvtab[((*pu++ << 8) | *pv++) + 3598];
          *dst++ = ytab[((*py++ + 15) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 7) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 2570];
          *dst++ = ytab[((*py++ + 13) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 5) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 3598];
          *dst++ = ytab[((*py++ + 15) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 7) << 4) | (uv & 15)];
          uv = uvtab[((*pu++ << 8) | *pv++) + 2570];
          *dst++ = ytab[((*py++ + 13) << 4) | (uv >> 4)];
          *dst++ = ytab[((*py++ + 5) << 4) | (uv & 15)];
        }
    }
}
#endif