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1 | $Id: README,v 1.7 2005/08/29 23:39:57 sbertin Exp $ | ||
2 | |||
3 | 1. Introduction | ||
4 | |||
5 | This is a driver for STMicroelectronics's CPiA2 (second generation | ||
6 | Colour Processor Interface ASIC) based cameras. This camera outputs an MJPEG | ||
7 | stream at up to vga size. It implements the Video4Linux interface as much as | ||
8 | possible. Since the V4L interface does not support compressed formats, only | ||
9 | an mjpeg enabled application can be used with the camera. We have modified the | ||
10 | gqcam application to view this stream. | ||
11 | |||
12 | The driver is implemented as two kernel modules. The cpia2 module | ||
13 | contains the camera functions and the V4L interface. The cpia2_usb module | ||
14 | contains usb specific functions. The main reason for this was the size of the | ||
15 | module was getting out of hand, so I separted them. It is not likely that | ||
16 | there will be a parallel port version. | ||
17 | |||
18 | FEATURES: | ||
19 | - Supports cameras with the Vision stv6410 (CIF) and stv6500 (VGA) cmos | ||
20 | sensors. I only have the vga sensor, so can't test the other. | ||
21 | - Image formats: VGA, QVGA, CIF, QCIF, and a number of sizes in between. | ||
22 | VGA and QVGA are the native image sizes for the VGA camera. CIF is done | ||
23 | in the coprocessor by scaling QVGA. All other sizes are done by clipping. | ||
24 | - Palette: YCrCb, compressed with MJPEG. | ||
25 | - Some compression parameters are settable. | ||
26 | - Sensor framerate is adjustable (up to 30 fps CIF, 15 fps VGA). | ||
27 | - Adjust brightness, color, contrast while streaming. | ||
28 | - Flicker control settable for 50 or 60 Hz mains frequency. | ||
29 | |||
30 | 2. Making and installing the stv672 driver modules: | ||
31 | |||
32 | Requirements: | ||
33 | ------------- | ||
34 | This should work with 2.4 (2.4.23 and later) and 2.6 kernels, but has | ||
35 | only been tested on 2.6. Video4Linux must be either compiled into the kernel or | ||
36 | available as a module. Video4Linux2 is automatically detected and made | ||
37 | available at compile time. | ||
38 | |||
39 | Compiling: | ||
40 | ---------- | ||
41 | As root, do a make install. This will compile and install the modules | ||
42 | into the media/video directory in the module tree. For 2.4 kernels, use | ||
43 | Makefile_2.4 (aka do make -f Makefile_2.4 install). | ||
44 | |||
45 | Setup: | ||
46 | ------ | ||
47 | Use 'modprobe cpia2' to load and 'modprobe -r cpia2' to unload. This | ||
48 | may be done automatically by your distribution. | ||
49 | |||
50 | 3. Driver options | ||
51 | |||
52 | Option Description | ||
53 | ------ ----------- | ||
54 | video_nr video device to register (0=/dev/video0, etc) | ||
55 | range -1 to 64. default is -1 (first available) | ||
56 | If you have more than 1 camera, this MUST be -1. | ||
57 | buffer_size Size for each frame buffer in bytes (default 68k) | ||
58 | num_buffers Number of frame buffers (1-32, default 3) | ||
59 | alternate USB Alternate (2-7, default 7) | ||
60 | flicker_freq Frequency for flicker reduction(50 or 60, default 60) | ||
61 | flicker_mode 0 to disable, or 1 to enable flicker reduction. | ||
62 | (default 0). This is only effective if the camera | ||
63 | uses a stv0672 coprocessor. | ||
64 | |||
65 | Setting the options: | ||
66 | -------------------- | ||
67 | If you are using modules, edit /etc/modules.conf and add an options | ||
68 | line like this: | ||
69 | options cpia2 num_buffers=3 buffer_size=65535 | ||
70 | |||
71 | If the driver is compiled into the kernel, at boot time specify them | ||
72 | like this: | ||
73 | cpia2=num_buffers:3,buffer_size:65535 | ||
74 | |||
75 | What buffer size should I use? | ||
76 | ------------------------------ | ||
77 | The maximum image size depends on the alternate you choose, and the | ||
78 | frame rate achieved by the camera. If the compression engine is able to | ||
79 | keep up with the frame rate, the maximum image size is given by the table | ||
80 | below. | ||
81 | The compression engine starts out at maximum compression, and will | ||
82 | increase image quality until it is close to the size in the table. As long | ||
83 | as the compression engine can keep up with the frame rate, after a short time | ||
84 | the images will all be about the size in the table, regardless of resolution. | ||
85 | At low alternate settings, the compression engine may not be able to | ||
86 | compress the image enough and will reduce the frame rate by producing larger | ||
87 | images. | ||
88 | The default of 68k should be good for most users. This will handle | ||
89 | any alternate at frame rates down to 15fps. For lower frame rates, it may | ||
90 | be necessary to increase the buffer size to avoid having frames dropped due | ||
91 | to insufficient space. | ||
92 | |||
93 | Image size(bytes) | ||
94 | Alternate bytes/ms 15fps 30fps | ||
95 | 2 128 8533 4267 | ||
96 | 3 384 25600 12800 | ||
97 | 4 640 42667 21333 | ||
98 | 5 768 51200 25600 | ||
99 | 6 896 59733 29867 | ||
100 | 7 1023 68200 34100 | ||
101 | |||
102 | How many buffers should I use? | ||
103 | ------------------------------ | ||
104 | For normal streaming, 3 should give the best results. With only 2, | ||
105 | it is possible for the camera to finish sending one image just after a | ||
106 | program has started reading the other. If this happens, the driver must drop | ||
107 | a frame. The exception to this is if you have a heavily loaded machine. In | ||
108 | this case use 2 buffers. You are probably not reading at the full frame rate. | ||
109 | If the camera can send multiple images before a read finishes, it could | ||
110 | overwrite the third buffer before the read finishes, leading to a corrupt | ||
111 | image. Single and double buffering have extra checks to avoid overwriting. | ||
112 | |||
113 | 4. Using the camera | ||
114 | |||
115 | We are providing a modified gqcam application to view the output. In | ||
116 | order to avoid confusion, here it is called mview. There is also the qx5view | ||
117 | program which can also control the lights on the qx5 microscope. MJPEG Tools | ||
118 | (http://mjpeg.sourceforge.net) can also be used to record from the camera. | ||
119 | |||
120 | 5. Notes to developers: | ||
121 | |||
122 | - This is a driver version stripped of the 2.4 back compatibility | ||
123 | and old MJPEG ioctl API. See cpia2.sf.net for 2.4 support. | ||
124 | |||
125 | 6. Thanks: | ||
126 | |||
127 | - Peter Pregler <Peter_Pregler@email.com>, | ||
128 | Scott J. Bertin <scottbertin@yahoo.com>, and | ||
129 | Jarl Totland <Jarl.Totland@bdc.no> for the original cpia driver, which | ||
130 | this one was modelled from. | ||
diff --git a/Documentation/video4linux/cpia2_overview.txt b/Documentation/video4linux/cpia2_overview.txt new file mode 100644 index 000000000000..a6e53665216b --- /dev/null +++ b/Documentation/video4linux/cpia2_overview.txt | |||
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1 | Programmer's View of Cpia2 | ||
2 | |||
3 | Cpia2 is the second generation video coprocessor from VLSI Vision Ltd (now a | ||
4 | division of ST Microelectronics). There are two versions. The first is the | ||
5 | STV0672, which is capable of up to 30 frames per second (fps) in frame sizes | ||
6 | up to CIF, and 15 fps for VGA frames. The STV0676 is an improved version, | ||
7 | which can handle up to 30 fps VGA. Both coprocessors can be attached to two | ||
8 | CMOS sensors - the vvl6410 CIF sensor and the vvl6500 VGA sensor. These will | ||
9 | be referred to as the 410 and the 500 sensors, or the CIF and VGA sensors. | ||
10 | |||
11 | The two chipsets operate almost identically. The core is an 8051 processor, | ||
12 | running two different versions of firmware. The 672 runs the VP4 video | ||
13 | processor code, the 676 runs VP5. There are a few differences in register | ||
14 | mappings for the two chips. In these cases, the symbols defined in the | ||
15 | header files are marked with VP4 or VP5 as part of the symbol name. | ||
16 | |||
17 | The cameras appear externally as three sets of registers. Setting register | ||
18 | values is the only way to control the camera. Some settings are | ||
19 | interdependant, such as the sequence required to power up the camera. I will | ||
20 | try to make note of all of these cases. | ||
21 | |||
22 | The register sets are called blocks. Block 0 is the system block. This | ||
23 | section is always powered on when the camera is plugged in. It contains | ||
24 | registers that control housekeeping functions such as powering up the video | ||
25 | processor. The video processor is the VP block. These registers control | ||
26 | how the video from the sensor is processed. Examples are timing registers, | ||
27 | user mode (vga, qvga), scaling, cropping, framerates, and so on. The last | ||
28 | block is the video compressor (VC). The video stream sent from the camera is | ||
29 | compressed as Motion JPEG (JPEGA). The VC controls all of the compression | ||
30 | parameters. Looking at the file cpia2_registers.h, you can get a full view | ||
31 | of these registers and the possible values for most of them. | ||
32 | |||
33 | One or more registers can be set or read by sending a usb control message to | ||
34 | the camera. There are three modes for this. Block mode requests a number | ||
35 | of contiguous registers. Random mode reads or writes random registers with | ||
36 | a tuple structure containing address/value pairs. The repeat mode is only | ||
37 | used by VP4 to load a firmware patch. It contains a starting address and | ||
38 | a sequence of bytes to be written into a gpio port. \ No newline at end of file | ||