yuv2rgb.c

文件内包含H.263视频编码算法和解码算法2个文件

/************************************************************************
 *
 *  yuv2rgb.c, colour space conversion for tmndecode (H.263 decoder)
  */


#include "config.h"
#include "tmndec.h"
#include "global.h"

#ifdef DISPLAY
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#endif


#ifdef DISPLAY

#undef INTERPOLATE

/*
 * Erik Corry's multi-byte dither routines.
 *
 * The basic idea is that the Init generates all the necessary tables.
 * The tables incorporate the information about the layout of pixels
 * in the XImage, so that it should be able to cope with 15-bit, 16-bit
 * 24-bit (non-packed) and 32-bit (10-11 bits per color!) screens.
 * At present it cannot cope with 24-bit packed mode, since this involves
 * getting down to byte level again. It is assumed that the bits for each
 * color are contiguous in the longword.
 * 
 * Writing to memory is done in shorts or ints. (Unfortunately, short is not
 * very fast on Alpha, so there is room for improvement here). There is no
 * dither time check for overflow - instead the tables have slack at
 * each end. This is likely to be faster than an 'if' test as many modern
 * architectures are really bad at ifs. Potentially, each '&&' causes a 
 * pipeline flush!
 *
 * There is no shifting and fixed point arithmetic, as I really doubt you
 * can see the difference, and it costs. This may be just my bias, since I
 * heard that Intel is really bad at shifting.
 */

/* Gamma correction stuff */

#define GAMMA_CORRECTION(x) ((int)(pow((x) / 255.0, 1.0 / gammaCorrect) * 255.0))
#define CHROMA_CORRECTION256(x) ((x) >= 128 \
                    ? 128 + mmin(127, (int)(((x) - 128.0) * chromaCorrect)) \
                    : 128 - mmin(128, (int)((128.0 - (x)) * chromaCorrect)))
#define CHROMA_CORRECTION128(x) ((x) >= 0 \
                    ? mmin(127,  (int)(((x) * chromaCorrect))) \
                    : mmax(-128, (int)(((x) * chromaCorrect))))
#define CHROMA_CORRECTION256D(x) ((x) >= 128 \
                    ? 128.0 + mmin(127.0, (((x) - 128.0) * chromaCorrect)) \
                    : 128.0 - mmin(128.0, (((128.0 - (x)) * chromaCorrect))))
#define CHROMA_CORRECTION128D(x) ((x) >= 0 \
                    ? mmin(127.0,  ((x) * chromaCorrect)) \
                    : mmax(-128.0, ((x) * chromaCorrect)))


/* Flag for gamma correction */
int gammaCorrectFlag = 0;
double gammaCorrect = 1.0;

/* Flag for chroma correction */
int chromaCorrectFlag = 0;
double chromaCorrect = 1.0;

/*
 * How many 1 bits are there in the longword.
 * Low performance, do not call often.
 */
static int
number_of_bits_set(a)
unsigned long a;
{
    if(!a) return 0;
    if(a & 1) return 1 + number_of_bits_set(a >> 1);
    return(number_of_bits_set(a >> 1));
}

/*
 * Shift the 0s in the least significant end out of the longword.
 * Low performance, do not call often.
 */
static unsigned long
shifted_down(a)
unsigned long a;
{
    if(!a) return 0;
    if(a & 1) return a;
    return a >> 1;
}

/*
 * How many 0 bits are there at most significant end of longword.
 * Low performance, do not call often.
 */
static int
free_bits_at_top(a)
unsigned long a;
{
      /* assume char is 8 bits */
    if(!a) return sizeof(unsigned long) * 8;
        /* assume twos complement */
    if(((long)a) < 0l) return 0;
    return 1 + free_bits_at_top ( a << 1);
}

/*
 * How many 0 bits are there at least significant end of longword.
 * Low performance, do not call often.
 */
static int
free_bits_at_bottom(a)
unsigned long a;
{
      /* assume char is 8 bits */
    if(!a) return sizeof(unsigned long) * 8;
    if(((long)a) & 1l) return 0;
    return 1 + free_bits_at_bottom ( a >> 1);
}

static int *L_tab, *Cr_r_tab, *Cr_g_tab, *Cb_g_tab, *Cb_b_tab;

/*
 * We define tables that convert a color value between -256 and 512
 * into the R, G and B parts of the pixel. The normal range is 0-255.
 */

static long *r_2_pix;
static long *g_2_pix;
static long *b_2_pix;
static long *r_2_pix_alloc;
static long *g_2_pix_alloc;
static long *b_2_pix_alloc;



/*
 *--------------------------------------------------------------
 *
 * InitColor16Dither --
 *
 *	To get rid of the multiply and other conversions in color
 *	dither, we use a lookup table.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The lookup tables are initialized.
 *
 *--------------------------------------------------------------
 */

void
InitColorDither(thirty2)
int thirty2;
{
    extern XImage *ximage;
    extern unsigned long wpixel[3];
    /*
     * misuse of the wpixel array for the pixel masks. Note that this
     * implies that the window is created before this routine is called
     */

     
    unsigned long red_mask = wpixel[0];
    unsigned long green_mask = wpixel[1];
    unsigned long blue_mask = wpixel[2];

    int CR, CB, i;

    if (ximage->bits_per_pixel == 24) /* not necessary in non-packed mode */
      init_dither_tab();

    L_tab    = (int *)malloc(256*sizeof(int)); 
    Cr_r_tab = (int *)malloc(256*sizeof(int));
    Cr_g_tab = (int *)malloc(256*sizeof(int));
    Cb_g_tab = (int *)malloc(256*sizeof(int));
    Cb_b_tab = (int *)malloc(256*sizeof(int));

    r_2_pix_alloc = (long *)malloc(768*sizeof(long));
    g_2_pix_alloc = (long *)malloc(768*sizeof(long));
    b_2_pix_alloc = (long *)malloc(768*sizeof(long));

    if (L_tab == NULL ||
        Cr_r_tab == NULL ||
        Cr_g_tab == NULL ||
        Cb_g_tab == NULL ||
        Cb_b_tab == NULL ||
        r_2_pix_alloc == NULL ||
        g_2_pix_alloc == NULL ||
        b_2_pix_alloc == NULL) {
      fprintf(stderr, "Could not get enough memory in InitColorDither\n");
      exit(1);
    }

    for (i=0; i<256; i++) {
      L_tab[i] = i;
      if (gammaCorrectFlag) {
        L_tab[i] = GAMMA_CORRECTION(i);
      }
      
      CB = CR = i;

      if (chromaCorrectFlag) {
        CB -= 128; 
        CB = CHROMA_CORRECTION128(CB);
        CR -= 128;
        CR = CHROMA_CORRECTION128(CR);
      } else {
        CB -= 128; CR -= 128;
      }
/* was
      Cr_r_tab[i] =  1.596 * CR;
      Cr_g_tab[i] = -0.813 * CR;
      Cb_g_tab[i] = -0.391 * CB;   
      Cb_b_tab[i] =  2.018 * CB;
  but they were just messed up.
  Then was (_Video Deymstified_):
      Cr_r_tab[i] =  1.366 * CR;
      Cr_g_tab[i] = -0.700 * CR;
      Cb_g_tab[i] = -0.334 * CB;   
      Cb_b_tab[i] =  1.732 * CB;
  but really should be:
   (from ITU-R BT.470-2 System B, G and SMPTE 170M )
*/
      Cr_r_tab[i] =  (0.419/0.299) * CR;
      Cr_g_tab[i] = -(0.299/0.419) * CR;
      Cb_g_tab[i] = -(0.114/0.331) * CB; 
      Cb_b_tab[i] =  (0.587/0.331) * CB;

/*
  though you could argue for:
    SMPTE 240M
      Cr_r_tab[i] =  (0.445/0.212) * CR;
      Cr_g_tab[i] = -(0.212/0.445) * CR;
      Cb_g_tab[i] = -(0.087/0.384) * CB; 
      Cb_b_tab[i] =  (0.701/0.384) * CB;
    FCC 
      Cr_r_tab[i] =  (0.421/0.30) * CR;
      Cr_g_tab[i] = -(0.30/0.421) * CR;
      Cb_g_tab[i] = -(0.11/0.331) * CB; 
      Cb_b_tab[i] =  (0.59/0.331) * CB;
    ITU-R BT.709 
      Cr_r_tab[i] =  (0.454/0.2125) * CR;
      Cr_g_tab[i] = -(0.2125/0.454) * CR;
      Cb_g_tab[i] = -(0.0721/0.386) * CB; 
      Cb_b_tab[i] =  (0.7154/0.386) * CB;
*/
    }

    /* 
     * Set up entries 0-255 in rgb-to-pixel value tables.
     */
    for (i = 0; i < 256; i++) {
      r_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(red_mask));
      r_2_pix_alloc[i + 256] <<= free_bits_at_bottom(red_mask);
      g_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(green_mask));
      g_2_pix_alloc[i + 256] <<= free_bits_at_bottom(green_mask);
      b_2_pix_alloc[i + 256] = i >> (8 - number_of_bits_set(blue_mask));
      b_2_pix_alloc[i + 256] <<= free_bits_at_bottom(blue_mask);
      /*
       * If we have 16-bit output depth, then we double the value
       * in the top word. This means that we can write out both
       * pixels in the pixel doubling mode with one op. It is 
       * harmless in the normal case as storing a 32-bit value
       * through a short pointer will lose the top bits anyway.
       * A similar optimisation for Alpha for 64 bit has been
       * prepared for, but is not yet implemented.
       */
      if(!thirty2) {

        r_2_pix_alloc[i + 256] |= (r_2_pix_alloc[i + 256]) << 16;
        g_2_pix_alloc[i + 256] |= (g_2_pix_alloc[i + 256]) << 16;
        b_2_pix_alloc[i + 256] |= (b_2_pix_alloc[i + 256]) << 16;

      }
#ifdef SIXTYFOUR_BIT
      if(thirty2) {

        r_2_pix_alloc[i + 256] |= (r_2_pix_alloc[i + 256]) << 32;
        g_2_pix_alloc[i + 256] |= (g_2_pix_alloc[i + 256]) << 32;
        b_2_pix_alloc[i + 256] |= (b_2_pix_alloc[i + 256]) << 32;