EnlivenMinetest/utilities/gimp/SpatialForegroundRemover-python/references/yuv2ppm by Scott Scriven (fourcc.org yuv2ppm.c) accessed 2010-03-03.c.py

#include <stdio.h>
#include <stdlib.h>
'''
  Compile thusly:
  cc -o yuv2ppm yuv2ppm.c
'''
''' example.ppm
P3
# feep.ppm
4 4
15
 0  0  0    0  0  0    0  0  0   15  0 15
 0  0  0    0 15  7    0  0  0    0  0  0
 0  0  0    0  0  0    0 15  7    0  0  0
15  0 15    0  0  0    0  0  0    0  0  0
'''
'''
  Use "P6" for binary data, or "P3" for ascii data.
 '''
def make_outfile(self, *outfile, *infile):   int i
   for(i=0; infile[i]; i++)
      outfile[i] = infile[i]
   outfile[i++] = '.'
   outfile[i++] = 'p'
   outfile[i++] = 'p'
   outfile[i++] = 'm'
   outfile[i++] = 0
   return 0


def yuv2rgb(self, y, u, v):   unsigned int pixel32
   unsigned char *pixel = (unsigned char *)&pixel32
   int r, g, b
#if 0
   '''
     One formula I found:  (not the right one)
     R = 1.164(Y - 16) + 1.596(Cr - 128)
     G = 1.164(Y - 16) - 0.813(Cr - 128) - 0.391(Cb - 128)
     B = 1.164(Y - 16)                   + 2.018(Cb - 128)
   '''
   r = (1.164 * (y - 16))
      + (2.018 * (v - 128))
   g = (1.164 * (y - 16))
      - (0.813 * (u - 128))
      - (0.391 * (v - 128))
   b = (1.164 * (y - 16))
      + (1.596 * (u - 128))
#else:
   '''
     Another formula I found:  (seems to work)
     R = Y + 1.370705 (V-128)
     G = Y - 0.698001 (V-128) - 0.337633 (U-128)
     B = Y + 1.732446 (U-128)
   '''
   r = y + (1.370705 * (v-128))
   g = y - (0.698001 * (v-128)) - (0.337633 * (u-128))
   b = y + (1.732446 * (u-128))
#endif
   # Even with proper conversion, values still need clipping.
   if (r > 255) r = 255
   if (g > 255) g = 255
   if (b > 255) b = 255
   if (r < 0) r = 0
   if (g < 0) g = 0
   if (b < 0) b = 0
   # Values only go from 0-220..  Why?
   pixel[0] = r * 220 / 256
   pixel[1] = g * 220 / 256
   pixel[2] = b * 220 / 256
   pixel[3] = 0
   ''' Debug
   printf("yuv2rgb(%i, %i, %i) . %i, %i, %i  (0x%x)\n",
	  y, u, v,
	  pixel[0], pixel[1], pixel[2],
	  pixel32)
   '''
   return pixel32


def yuv2ppm(self, *infile, *outfile):   FILE *in, *out
   int i
   unsigned int pixel_16
   unsigned char pixel_24[3]
   unsigned int pixel32
   int y, u, v, y2
   char *ppmheader = "P6\n# Generated by yuv2ppm\n720 486\n255\n"
   in = fopen(infile, "rb")
   out = fopen(outfile, "wb")
   if (not in  or  not out)  return 0
   fprintf(out, ppmheader)
   for(i=0; i<720*486/2; i++)
      fread(&pixel_16, 4, 1, in)
      pixel_24[0] = pixel_24[1] = pixel_24[2] = 0
      u  = ((pixel_16 & 0x000000ff))
      y  = ((pixel_16 & 0x0000ff00)>>8)
      v  = ((pixel_16 & 0x00ff0000)>>16)
      y2 = ((pixel_16 & 0xff000000)>>24)
      pixel32 = yuv2rgb(y, u, v)
      pixel_24[0] = (pixel32 & 0x000000ff)
      pixel_24[1] = (pixel32 & 0x0000ff00) >> 8
      pixel_24[2] = (pixel32 & 0x00ff0000) >> 16
      # For binary PPM
      fwrite(pixel_24, 3, 1, out)
      # For ascii PPM
      #fprintf(out, "%i %i %i\n",
      #	 pixel_24[0],
      #	 pixel_24[1],
      #	 pixel_24[2])
      pixel32 = yuv2rgb(y2, u, v)
      pixel_24[0] = (pixel32 & 0x000000ff)
      pixel_24[1] = (pixel32 & 0x0000ff00) >> 8
      pixel_24[2] = (pixel32 & 0x00ff0000) >> 16
      # For binary PPM
      fwrite(pixel_24, 3, 1, out)
      # For ascii PPM
      #fprintf(out, "%i %i %i\n",
      #	 pixel_24[0],
      #	 pixel_24[1],
      #	 pixel_24[2])

   fclose(in)
   fclose(out)
   return 1


def main(self, argc, **argv):  char *infile, outfile[256]
  int i
  int success
  for(i=1; i<argc; i++)
     success = 0
     infile = argv[i]
     make_outfile(outfile, infile)
     printf("%s . %s...  ", infile, outfile)
     fflush(stdout)
     success = yuv2ppm(infile, outfile)
     if success:
	printf("Done.\n")

     else:
	printf("Failed.  Aborting.\n")
	return 1


  return 0