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/* readyuv.c - read an Abekas A66 style image file. Steve Simon, 2003 */
#include <u.h>
#include <libc.h>
#include <bio.h>
#include <draw.h>
#include <ctype.h>
#include "imagefile.h"
/*
* ITU/CCIR Rec601 states:
*
* R = y + 1.402 * Cr
* B = Y + 1.77305 * Cb
* G = Y - 0.72414 * Cr - 0.34414 * Cb
*
* using 8 bit traffic
* Y = 16 + 219 * Y
* Cr = 128 + 224 * Cr
* Cb = 128 + 224 * Cb
* or, if 10bit is used
* Y = 64 + 876 * Y
* Cr = 512 + 896 * Cr
* Cb = 512 + 896 * Cb
*/
enum {
PAL = 576, NTSC = 486 };
static int lsbtab[] = { 6, 4, 2, 0};
static int
clip(int x)
{
x >>= 18;
if (x > 255)
return 0xff;
if (x <= 0)
return 0;
return x;
}
Rawimage**
Breadyuv(Biobuf *bp, int colourspace)
{
Dir * d;
Rawimage * a, **array;
char *e, ebuf[128];
ushort * mux, *end, *frm;
uchar buf[720 * 2], *r, *g, *b;
int y1, y2, cb, cr, sz, c, l, w, base, bits, lines;
frm = 0;
if (colourspace != CYCbCr) {
errstr(ebuf, sizeof ebuf); /* throw it away */
werrstr("ReadYUV: unknown colour space %d", colourspace);
return nil;
}
if ((a = calloc(sizeof(Rawimage), 1)) == nil)
sysfatal("no memory");
if ((array = calloc(sizeof(Rawimage * ), 2)) == nil)
sysfatal("no memory");
array[0] = a;
array[1] = nil;
if ((d = dirfstat(Bfildes(bp))) != nil) {
sz = d->length;
free(d);
} else {
fprint(2, "cannot stat input, assuming 720x576x10bit\n");
sz = 720 * PAL * 2L + (720 * PAL / 2L);
}
switch (sz) {
case 720 * PAL * 2: // 625 x 8bit
bits = 8;
lines = PAL;
break;
case 720 * NTSC * 2: // 525 x 8bit
bits = 8;
lines = NTSC;
break;
case 720 * PAL * 2 + (720 * PAL / 2) : // 625 x 10bit
bits = 10;
lines = PAL;
break;
case 720 * NTSC * 2 + (720 * NTSC / 2) : // 525 x 10bit
bits = 10;
lines = NTSC;
break;
default:
e = "unknown file size";
goto Error;
}
// print("bits=%d pixels=%d lines=%d\n", bits, 720, lines);
//
a->nchans = 3;
a->chandesc = CRGB;
a->chanlen = 720 * lines;
a->r = Rect(0, 0, 720, lines);
e = "no memory";
if ((frm = malloc(720 * 2 * lines * sizeof(ushort))) == nil)
goto Error;
for (c = 0; c < 3; c++)
if ((a->chans[c] = malloc(720 * lines)) == nil)
goto Error;
e = "read file";
for (l = 0; l < lines; l++) {
if (Bread(bp, buf, 720 * 2) == -1)
goto Error;
base = l * 720 * 2;
for (w = 0; w < 720 * 2; w++)
frm[base + w] = ((ushort)buf[w]) << 2;
}
if (bits == 10)
for (l = 0; l < lines; l++) {
if (Bread(bp, buf, 720 / 2) == -1)
goto Error;
base = l * 720 * 2;
for (w = 0; w < 720 * 2; w++)
frm[base + w] |= buf[w / 4] >> lsbtab[w % 4];
}
mux = frm;
end = frm + 720 * lines * 2;
r = a->chans[0];
g = a->chans[1];
b = a->chans[2];
while (mux < end) {
cb = *mux++ - 512;
y1 = (*mux++ - 64) * 76310;
cr = *mux++ - 512;
y2 = (*mux++ - 64) * 76310;
*r++ = clip((104635 * cr) + y1);
*g++ = clip((-25690 * cb + -53294 * cr) + y1);
*b++ = clip((132278 * cb) + y1);
*r++ = clip((104635 * cr) + y2);
*g++ = clip((-25690 * cb + -53294 * cr) + y2);
*b++ = clip((132278 * cb) + y2);
}
free(frm);
return array;
Error:
errstr(ebuf, sizeof ebuf);
if (ebuf[0] == 0)
strcpy(ebuf, e);
errstr(ebuf, sizeof ebuf);
for (c = 0; c < 3; c++)
free(a->chans[c]);
free(a->cmap);
free(array[0]);
free(array);
free(frm);
return nil;
}
Rawimage**
readyuv(int fd, int colorspace)
{
Rawimage * *a;
Biobuf b;
if (Binit(&b, fd, OREAD) < 0)
return nil;
a = Breadyuv(&b, colorspace);
Bterm(&b);
return a;
}
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