1 .. SPDX-License-Identifier: GPL-2.0
2
3 The cx2341x driver
4 ==================
5
6 Non-compressed file format
7 --------------------------
8
9 The cx23416 can produce (and the cx23415 can a
10 format of a YUV frame is 16x16 linear tiled NV
11
12 The format is YUV 4:2:0 which uses 1 Y byte pe
13 four pixels.
14
15 The data is encoded as two macroblock planes,
16 values, the second containing UV macroblocks.
17
18 The Y plane is divided into blocks of 16x16 pi
19 and from top to bottom. Each block is transmit
20
21 So the first 16 bytes are the first line of th
22 second 16 bytes are the second line of the top
23 transmitting this block the first line of the
24 first block is transmitted, etc.
25
26 The UV plane is divided into blocks of 16x8 UV
27 to right, top to bottom. Each block is transmi
28
29 So the first 16 bytes are the first line of th
30 contain 8 UV value pairs (16 bytes in total).
31 second line of 8 UV pairs of the top-left bloc
32 this block the first line of the block on the
33 transmitted, etc.
34
35 The code below is given as an example on how t
36 to separate Y, U and V planes. This code assum
37
38 The width of a frame is always 720 pixels, reg
39 width.
40
41 If the height is not a multiple of 32 lines, t
42 missing macroblocks at the end and is unusable
43 multiple of 32.
44
45 Raw format c example
46 ~~~~~~~~~~~~~~~~~~~~
47
48 .. code-block:: c
49
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53
54 static unsigned char frame[576*720*3/2
55 static unsigned char framey[576*720];
56 static unsigned char frameu[576*720 /
57 static unsigned char framev[576*720 /
58
59 static void de_macro_y(unsigned char*
60 {
61 unsigned int y, x, i;
62
63 // descramble Y plane
64 // dstride = 720 = w
65 // The Y plane is divided into blocks
66 // Each block in transmitted in turn,
67 for (y = 0; y < h; y += 16) {
68 for (x = 0; x < w; x += 16) {
69 for (i = 0; i < 16; i++) {
70 memcpy(dst + x + (y +
71 src += 16;
72 }
73 }
74 }
75 }
76
77 static void de_macro_uv(unsigned char
78 {
79 unsigned int y, x, i;
80
81 // descramble U/V plane
82 // dstride = 720 / 2 = w
83 // The U/V values are interlaced (UVUV
84 // Again, the UV plane is divided into
85 // Each block in transmitted in turn,
86 for (y = 0; y < h; y += 16) {
87 for (x = 0; x < w; x += 8) {
88 for (i = 0; i < 16; i++) {
89 int idx = x + (y + i)
90
91 dstu[idx+0] = src[0];
92 dstu[idx+1] = src[2];
93 dstu[idx+2] = src[4];
94 dstu[idx+3] = src[6];
95 dstu[idx+4] = src[8];
96 dstu[idx+5] = src[10];
97 dstu[idx+6] = src[12];
98 dstu[idx+7] = src[14];
99 src += 16;
100 }
101 }
102 }
103 }
104
105 /*************************************
106 int main(int argc, char **argv)
107 {
108 FILE *fin;
109 int i;
110
111 if (argc == 1) fin = stdin;
112 else fin = fopen(argv[1], "r");
113
114 if (fin == NULL) {
115 fprintf(stderr, "cannot open i
116 exit(-1);
117 }
118 while (fread(frame, sizeof(frame), 1,
119 de_macro_y(framey, frame, 720,
120 de_macro_uv(frameu, framev, fr
121 fwrite(framey, sizeof(framey),
122 fwrite(framev, sizeof(framev),
123 fwrite(frameu, sizeof(frameu),
124 }
125 fclose(fin);
126 return 0;
127 }
128
129
130 Format of embedded V4L2_MPEG_STREAM_VBI_FMT_IV
131 ----------------------------------------------
132
133 Author: Hans Verkuil <hverkuil@xs4all.nl>
134
135
136 This section describes the V4L2_MPEG_STREAM_VB
137 embedded in an MPEG-2 program stream. This for
138 hardware limitations of the ivtv driver (the d
139 chips), in particular a maximum size for the V
140 off when the MPEG stream is played back throug
141
142 The advantage of this format is it is very com
143 all lines can be stored while still fitting wi
144
145 The stream ID of the VBI data is 0xBD. The max
146 4 + 43 * 36, which is 4 bytes for a header and
147 header and a 42 bytes payload each. Anything b
148 the cx23415/6 firmware. Besides the data for t
149 for a bitmask determining which lines are capt
150 signifying that this data package contains V4L
151 If all lines are used, then there is no longer
152 two different magic numbers were introduced:
153
154 'itv0': After this magic number two unsigned l
155 unsigned long denote which lines of the first
156 the first unsigned long and bits 0-3 of the se
157 second field.
158
159 'ITV0': This magic number assumes all VBI line
160 implies that the bitmasks are 0xffffffff and 0
161
162 After these magic cookies (and the 8 byte bitm
163 captured VBI lines start:
164
165 For each line the least significant 4 bits of
166 Possible values are shown in the table below.
167 bytes.
168
169 Here is the list of possible data types:
170
171 .. code-block:: c
172
173 #define IVTV_SLICED_TYPE_TELETEXT
174 #define IVTV_SLICED_TYPE_CC
175 #define IVTV_SLICED_TYPE_WSS
176 #define IVTV_SLICED_TYPE_VPS
177
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