1 /* readyuv.c - read an Abekas A66 style image file.   Steve Simon, 2003 */
2 #include <u.h>
3 #include <libc.h>
4 #include <bio.h>
5 #include <draw.h>
6 #include <ctype.h>
7 #include "imagefile.h"
8 
9 /*
10  * ITU/CCIR Rec601 states:
11  *
12  * R = y + 1.402 * Cr
13  * B = Y + 1.77305 * Cb
14  * G = Y - 0.72414 * Cr - 0.34414 * Cb
15  *
16  *	using 8 bit traffic
17  * Y = 16 + 219 * Y
18  * Cr = 128 + 224 * Cr
19  * Cb = 128 + 224 * Cb
20  * 	or, if 10bit is used
21  * Y = 64 + 876 * Y
22  * Cr = 512 + 896 * Cr
23  * Cb = 512 + 896 * Cb
24  */
25 
26 enum {
27 	PAL = 576, NTSC = 486 };
28 
29 
30 static int lsbtab[] = { 6, 4, 2, 0};
31 
32 static int 
33 clip(int x)
34 {
35 	x >>= 18;
36 
37 	if (x > 255)
38 		return 0xff;
39 	if (x <= 0)
40 		return 0;
41 	return x;
42 }
43 
44 
45 Rawimage**
46 Breadyuv(Biobuf *bp, int colourspace)
47 {
48 	Dir * d;
49 	Rawimage * a, **array;
50 	char	*e, ebuf[128];
51 	ushort * mux, *end, *frm;
52 	uchar buf[720 * 2], *r, *g, *b;
53 	int	y1, y2, cb, cr, sz, c, l, w, base, bits, lines;
54 
55 	frm = 0;
56 	if (colourspace != CYCbCr) {
57 		errstr(ebuf, sizeof ebuf);	/* throw it away */
58 		werrstr("ReadYUV: unknown colour space %d", colourspace);
59 		return nil;
60 	}
61 
62 	if ((a = calloc(sizeof(Rawimage), 1)) == nil)
63 		sysfatal("no memory");
64 
65 	if ((array = calloc(sizeof(Rawimage * ), 2)) == nil)
66 		sysfatal("no memory");
67 	array[0] = a;
68 	array[1] = nil;
69 
70 	if ((d = dirfstat(Bfildes(bp))) != nil) {
71 		sz = d->length;
72 		free(d);
73 	} else {
74 		fprint(2, "cannot stat input, assuming 720x576x10bit\n");
75 		sz = 720 * PAL * 2L + (720 * PAL / 2L);
76 	}
77 
78 	switch (sz) {
79 	case 720 * PAL * 2:				// 625 x 8bit
80 		bits = 8;
81 		lines = PAL;
82 		break;
83 	case 720 * NTSC * 2:				// 525 x 8bit
84 		bits = 8;
85 		lines = NTSC;
86 		break;
87 	case 720 * PAL * 2 + (720 * PAL / 2) :		// 625 x 10bit
88 			bits = 10;
89 		lines = PAL;
90 		break;
91 	case 720 * NTSC * 2 + (720 * NTSC / 2) :	// 525 x 10bit
92 			bits = 10;
93 		lines = NTSC;
94 		break;
95 	default:
96 		e = "unknown file size";
97 		goto Error;
98 	}
99 
100 	//	print("bits=%d pixels=%d lines=%d\n", bits, 720, lines);
101 	//
102 	a->nchans = 3;
103 	a->chandesc = CRGB;
104 	a->chanlen = 720 * lines;
105 	a->r = Rect(0, 0, 720, lines);
106 
107 	e = "no memory";
108 	if ((frm = malloc(720 * 2 * lines * sizeof(ushort))) == nil)
109 		goto Error;
110 
111 	for (c = 0; c  < 3; c++)
112 		if ((a->chans[c] = malloc(720 * lines)) == nil)
113 			goto Error;
114 
115 	e = "read file";
116 	for (l = 0; l < lines; l++) {
117 		if (Bread(bp, buf, 720 * 2) == -1)
118 			goto Error;
119 
120 		base = l * 720 * 2;
121 		for (w = 0; w < 720 * 2; w++)
122 			frm[base + w] = ((ushort)buf[w]) << 2;
123 	}
124 
125 
126 	if (bits == 10)
127 		for (l = 0; l < lines; l++) {
128 			if (Bread(bp, buf, 720 / 2) == -1)
129 				goto Error;
130 
131 
132 			base = l * 720 * 2;
133 			for (w = 0; w < 720 * 2; w++)
134 				frm[base + w] |= buf[w / 4] >> lsbtab[w % 4];
135 		}
136 
137 	mux = frm;
138 	end = frm + 720 * lines * 2;
139 	r = a->chans[0];
140 	g = a->chans[1];
141 	b = a->chans[2];
142 
143 	while (mux < end) {
144 		cb = *mux++ - 512;
145 		y1 = (*mux++ - 64) * 76310;
146 		cr = *mux++ - 512;
147 		y2 = (*mux++ - 64) * 76310;
148 
149 		*r++ = clip((104635 * cr) + y1);
150 		*g++ = clip((-25690 * cb + -53294 * cr) + y1);
151 		*b++ = clip((132278 * cb) + y1);
152 
153 		*r++ = clip((104635 * cr) + y2);
154 		*g++ = clip((-25690 * cb + -53294 * cr) + y2);
155 		*b++ = clip((132278 * cb) + y2);
156 	}
157 	free(frm);
158 	return array;
159 
160 Error:
161 
162 	errstr(ebuf, sizeof ebuf);
163 	if (ebuf[0] == 0)
164 		strcpy(ebuf, e);
165 	errstr(ebuf, sizeof ebuf);
166 
167 	for (c = 0; c < 3; c++)
168 		free(a->chans[c]);
169 	free(a->cmap);
170 	free(array[0]);
171 	free(array);
172 	free(frm);
173 	return nil;
174 }
175 
176 
177 Rawimage**
178 readyuv(int fd, int colorspace)
179 {
180 	Rawimage * *a;
181 	Biobuf b;
182 
183 	if (Binit(&b, fd, OREAD) < 0)
184 		return nil;
185 	a = Breadyuv(&b, colorspace);
186 	Bterm(&b);
187 	return a;
188 }
189 
190