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/* ppmtoyuv.c - convert a portable pixmap into an Abekas YUV file
**
** by Marc Boucher
** Internet: marc@PostImage.COM
**
** Based on Example Conversion Program, A60/A64 Digital Video Interface
** Manual, page 69.
**
** Copyright (C) 1991 by DHD PostImage Inc.
** Copyright (C) 1987 by Abekas Video Systems Inc.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
*/
#include "ppm.h"
static void
convertRow(const pixel * const pixelrow,
unsigned int const cols,
unsigned char * const yuvBuf,
unsigned long * const uP,
unsigned long * const vP,
unsigned long * const u0P,
unsigned long * const v0P,
unsigned long * const y2CarryP) {
unsigned int col;
unsigned char * yuvptr;
for (col = 0, yuvptr = &yuvBuf[0]; col < cols; col += 2) {
unsigned long y1, y2, u1, u2, v1, v2;
{
/* first pixel gives Y and 0.5 of chroma */
pixval const r = PPM_GETR(pixelrow[col]);
pixval const g = PPM_GETG(pixelrow[col]);
pixval const b = PPM_GETB(pixelrow[col]);
y1 = 16829 * r + 33039 * g + 6416 * b + (*y2CarryP & 0xffff);
u1 = -4853 * r - 9530 * g + 14383 * b;
v1 = 14386 * r - 12046 * g - 2340 * b;
}
{
/* second pixel gives Y and 0.25 of chroma */
pixval const r = PPM_GETR(pixelrow[col + 1]);
pixval const g = PPM_GETG(pixelrow[col + 1]);
pixval const b = PPM_GETB(pixelrow[col + 1]);
y2 = 16829 * r + 33039 * g + 6416 * b + (y1 & 0xffff);
u2 = -2426 * r - 4765 * g + 7191 * b;
v2 = 7193 * r - 6023 * g - 1170 * b;
}
/* filter the chroma */
*uP = *u0P + u1 + u2 + (*uP & 0xffff);
*vP = *v0P + v1 + v2 + (*vP & 0xffff);
*u0P = u2;
*v0P = v2;
*yuvptr++ = (*uP >> 16) + 128;
*yuvptr++ = (y1 >> 16) + 16;
*yuvptr++ = (*vP >> 16) + 128;
*yuvptr++ = (y2 >> 16) + 16;
*y2CarryP = y2;
}
}
int
main(int argc, const char **argv) {
FILE * ifP;
pixel * pixelrow;
int rows, cols, format;
pixval maxval;
unsigned int row;
unsigned char * yuvBuf;
unsigned long u, v, u0, v0, y2Carry;
pm_proginit(&argc, argv);
if (argc-1 > 1)
pm_error("Too many arguments: %u. The only possible argument "
"is the name of the input file", argc-1);
if (argc-1 == 1)
ifP = pm_openr(argv[1]);
else
ifP = stdin;
ppm_readppminit(ifP, &cols, &rows, &maxval, &format);
if (cols % 2 != 0)
pm_error("Image must have even number of columns.\n"
"This image is %u columns wide. Try Pamcut.", cols);
pixelrow = ppm_allocrow(cols);
yuvBuf = (unsigned char *) pm_allocrow(cols, 2);
for (row = 0, u = v = u0 = v0 = y2Carry = 0; row < rows; ++row) {
ppm_readppmrow(ifP, pixelrow, cols, maxval, format);
convertRow(pixelrow, cols, yuvBuf, &u, &v, &u0, &v0, &y2Carry);
fwrite(yuvBuf, cols*2, 1, stdout);
}
pm_close(ifP);
return 0;
}
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