rotozoom.c

ffmpeg源码分析

/*
 * Generates a synthetic YUV video sequence suitable for codec testing.
 * GPLv2
 * rotozoom.c -> [e-mail]
 */
#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>

#define FIXP (1<<16)
#define MY_PI 205887 //(M_PI*FIX)

static int64_t int_pow(int64_t a, int p){
    int64_t v= FIXP;

    for(; p; p--){
        v*= a;
        v/= FIXP;
    }

    return v;
}

static int64_t int_sin(int64_t a){
    if(a<0) a= MY_PI-a; // 0..inf
    a %= 2*MY_PI;       // 0..2PI

    if(a>=MY_PI*3/2) a -= 2*MY_PI;  // -PI/2 .. 3PI/2
    if(a>=MY_PI/2  ) a = MY_PI - a; // -PI/2 ..  PI/2

    return a - int_pow(a, 3)/6 + int_pow(a, 5)/120 - int_pow(a, 7)/5040;
}

#define SCALEBITS 8
#define ONE_HALF  (1 << (SCALEBITS - 1))
#define FIX(x)    ((int) ((x) * (1L<<SCALEBITS) + 0.5))
typedef unsigned char UINT8;

static void rgb24_to_yuv420p(UINT8 *lum, UINT8 *cb, UINT8 *cr,
                              UINT8 *src, int width, int height)
{
    int wrap, wrap3, x, y;
    int r, g, b, r1, g1, b1;
    UINT8 *p;

    wrap = width;
    wrap3 = width * 3;
    p = src;
    for(y=0;y<height;y+=2) {
        for(x=0;x<width;x+=2) {
            r = p[0];
            g = p[1];
            b = p[2];
            r1 = r;
            g1 = g;
            b1 = b;
            lum[0] = (FIX(0.29900) * r + FIX(0.58700) * g +
                      FIX(0.11400) * b + ONE_HALF) >> SCALEBITS;
            r = p[3];
            g = p[4];
            b = p[5];
            r1 += r;
            g1 += g;
            b1 += b;
            lum[1] = (FIX(0.29900) * r + FIX(0.58700) * g +
                      FIX(0.11400) * b + ONE_HALF) >> SCALEBITS;
            p += wrap3;
            lum += wrap;

            r = p[0];
            g = p[1];
            b = p[2];
            r1 += r;
            g1 += g;
            b1 += b;
            lum[0] = (FIX(0.29900) * r + FIX(0.58700) * g +
                      FIX(0.11400) * b + ONE_HALF) >> SCALEBITS;
            r = p[3];
            g = p[4];
            b = p[5];
            r1 += r;
            g1 += g;
            b1 += b;
            lum[1] = (FIX(0.29900) * r + FIX(0.58700) * g +
                      FIX(0.11400) * b + ONE_HALF) >> SCALEBITS;

            cb[0] = ((- FIX(0.16874) * r1 - FIX(0.33126) * g1 +
                      FIX(0.50000) * b1 + 4 * ONE_HALF - 1) >> (SCALEBITS + 2)) + 128;
            cr[0] = ((FIX(0.50000) * r1 - FIX(0.41869) * g1 -
                     FIX(0.08131) * b1 + 4 * ONE_HALF - 1) >> (SCALEBITS + 2)) + 128;

            cb++;
            cr++;
            p += -wrap3 + 2 * 3;
            lum += -wrap + 2;
        }
        p += wrap3;
        lum += wrap;
    }
}

/* cif format */
#define DEFAULT_WIDTH   352
#define DEFAULT_HEIGHT  288
#define DEFAULT_NB_PICT 50

void pgmyuv_save(const char *filename, int w, int h,
                 unsigned char *rgb_tab)
{
    FILE *f;
    int i, h2, w2;
    unsigned char *cb, *cr;
    unsigned char *lum_tab, *cb_tab, *cr_tab;

    lum_tab = malloc(w * h);
    cb_tab = malloc((w * h) / 4);
    cr_tab = malloc((w * h) / 4);

    rgb24_to_yuv420p(lum_tab, cb_tab, cr_tab, rgb_tab, w, h);

    f = fopen(filename,"wb");
    fprintf(f, "P5\n%d %d\n%d\n", w, (h * 3) / 2, 255);
    fwrite(lum_tab, 1, w * h, f);
    h2 = h / 2;
    w2 = w / 2;
    cb = cb_tab;
    cr = cr_tab;
    for(i=0;i<h2;i++) {
        fwrite(cb, 1, w2, f);
        fwrite(cr, 1, w2, f);
        cb += w2;
        cr += w2;
    }
    fclose(f);

    free(lum_tab);
    free(cb_tab);
    free(cr_tab);
}

unsigned char *rgb_tab;
int width, height, wrap;

void put_pixel(int x, int y, int r, int g, int b)
{
    unsigned char *p;

    if (x < 0 || x >= width ||
        y < 0 || y >= height)
        return;

    p = rgb_tab + y * wrap + x * 3;
    p[0] = r;
    p[1] = g;
    p[2] = b;
}

unsigned char tab_r[256*256];
unsigned char tab_g[256*256];
unsigned char tab_b[256*256];

int teta = 0;
int h_cos [360];
int h_sin [360];

static int ipol(uint8_t *src, int x, int y){
    int int_x= x>>16;
    int int_y= y>>16;
    int frac_x= x&0xFFFF;
    int frac_y= y&0xFFFF;
    int s00= src[ ( int_x   &255) + 256*( int_y   &255) ];
    int s01= src[ ((int_x+1)&255) + 256*( int_y   &255) ];
    int s10= src[ ( int_x   &255) + 256*((int_y+1)&255) ];
    int s11= src[ ((int_x+1)&255) + 256*((int_y+1)&255) ];
    int s0= (((1<<16) - frac_x)*s00 + frac_x*s01)>>8;
    int s1= (((1<<16) - frac_x)*s10 + frac_x*s11)>>8;

    return (((1<<16) - frac_y)*s0 + frac_y*s1)>>24;
}

void gen_image(int num, int w, int h)
{
  const int c = h_cos [teta];
  const int s = h_sin [teta];

  const int xi = -(w/2) * c;
  const int yi =  (w/2) * s;

  const int xj = -(h/2) * s;
  const int yj = -(h/2) * c;
  int i,j;

  int x,y;
  int xprime = xj;
  int yprime = yj;


  for (j=0;j<h;j++) {

    x = xprime + xi + FIXP*w/2;
    xprime += s;

    y = yprime + yi + FIXP*h/2;
    yprime += c;

    for ( i=0 ; i<w ; i++ ) {
      x += c;
      y -= s;
#if 1
      put_pixel(i, j, ipol(tab_r, x, y), ipol(tab_g, x, y), ipol(tab_b, x, y));
#else
      {
          unsigned dep;
          dep = ((x>>16)&255) + (((y>>16)&255)<<8);
          put_pixel(i, j, tab_r[dep], tab_g[dep], tab_b[dep]);
      }
#endif
    }
  }
  teta = (teta+1) % 360;
}

#define W 256
#define H 256

void init_demo(const char *filename) {
  int i,j;
  int h;
  int radian;
  char line[3 * W];

  FILE *fichier;

  fichier = fopen(filename,"rb");
  if (!fichier) {
      perror(filename);
      exit(1);
  }

  fread(line, 1, 15, fichier);
  for (i=0;i<H;i++) {
    fread(line,1,3*W,fichier);
    for (j=0;j<W;j++) {
          tab_r[W*i+j] = line[3*j    ];
          tab_g[W*i+j] = line[3*j + 1];
          tab_b[W*i+j] = line[3*j + 2];
    }
  }
  fclose(fichier);

  /* tables sin/cos */
  for (i=0;i<360;i++) {
    radian = 2*i*MY_PI/360;
    h = 2*FIXP + int_sin (radian);
    h_cos[i] = ( h * int_sin (radian + MY_PI/2) )/2/FIXP;
    h_sin[i] = ( h * int_sin (radian          ) )/2/FIXP;
  }
}

int main(int argc, char **argv)
{
    int w, h, i;
    char buf[1024];

    if (argc != 3) {
        printf("usage: %s directory/ image.pnm\n"
               "generate a test video stream\n", argv[0]);
        exit(1);
    }

    w = DEFAULT_WIDTH;
    h = DEFAULT_HEIGHT;

    rgb_tab = malloc(w * h * 3);
    wrap = w * 3;
    width = w;
    height = h;

    init_demo(argv[2]);

    for(i=0;i<DEFAULT_NB_PICT;i++) {
        snprintf(buf, sizeof(buf), "%s%02d.pgm", argv[1], i);
        gen_image(i, w, h);
        pgmyuv_save(buf, w, h, rgb_tab);
    }

    free(rgb_tab);
    return 0;
}