diff options
Diffstat (limited to 'Documentation/media/v4l-drivers/cpia2.rst')
| -rw-r--r-- | Documentation/media/v4l-drivers/cpia2.rst | 195 |
1 files changed, 0 insertions, 195 deletions
diff --git a/Documentation/media/v4l-drivers/cpia2.rst b/Documentation/media/v4l-drivers/cpia2.rst deleted file mode 100644 index a86baa1c83f1..000000000000 --- a/Documentation/media/v4l-drivers/cpia2.rst +++ /dev/null @@ -1,195 +0,0 @@ -.. SPDX-License-Identifier: GPL-2.0 - -The cpia2 driver -================ - -Authors: Peter Pregler <Peter_Pregler@email.com>, -Scott J. Bertin <scottbertin@yahoo.com>, and -Jarl Totland <Jarl.Totland@bdc.no> for the original cpia driver, which -this one was modelled from. - -Introduction ------------- - -This is a driver for STMicroelectronics's CPiA2 (second generation -Colour Processor Interface ASIC) based cameras. This camera outputs an MJPEG -stream at up to vga size. It implements the Video4Linux interface as much as -possible. Since the V4L interface does not support compressed formats, only -an mjpeg enabled application can be used with the camera. We have modified the -gqcam application to view this stream. - -The driver is implemented as two kernel modules. The cpia2 module -contains the camera functions and the V4L interface. The cpia2_usb module -contains usb specific functions. The main reason for this was the size of the -module was getting out of hand, so I separated them. It is not likely that -there will be a parallel port version. - -Features --------- - -- Supports cameras with the Vision stv6410 (CIF) and stv6500 (VGA) cmos - sensors. I only have the vga sensor, so can't test the other. -- Image formats: VGA, QVGA, CIF, QCIF, and a number of sizes in between. - VGA and QVGA are the native image sizes for the VGA camera. CIF is done - in the coprocessor by scaling QVGA. All other sizes are done by clipping. -- Palette: YCrCb, compressed with MJPEG. -- Some compression parameters are settable. -- Sensor framerate is adjustable (up to 30 fps CIF, 15 fps VGA). -- Adjust brightness, color, contrast while streaming. -- Flicker control settable for 50 or 60 Hz mains frequency. - -Making and installing the stv672 driver modules ------------------------------------------------ - -Requirements -~~~~~~~~~~~~ - -Video4Linux must be either compiled into the kernel or -available as a module. Video4Linux2 is automatically detected and made -available at compile time. - -Setup -~~~~~ - -Use 'modprobe cpia2' to load and 'modprobe -r cpia2' to unload. This -may be done automatically by your distribution. - -Driver options -~~~~~~~~~~~~~~ - -.. tabularcolumns:: |p{13ex}|L| - - -============== ======================================================== -Option Description -============== ======================================================== -video_nr video device to register (0=/dev/video0, etc) - range -1 to 64. default is -1 (first available) - If you have more than 1 camera, this MUST be -1. -buffer_size Size for each frame buffer in bytes (default 68k) -num_buffers Number of frame buffers (1-32, default 3) -alternate USB Alternate (2-7, default 7) -flicker_freq Frequency for flicker reduction(50 or 60, default 60) -flicker_mode 0 to disable, or 1 to enable flicker reduction. - (default 0). This is only effective if the camera - uses a stv0672 coprocessor. -============== ======================================================== - -Setting the options -~~~~~~~~~~~~~~~~~~~ - -If you are using modules, edit /etc/modules.conf and add an options -line like this: - -.. code-block:: none - - options cpia2 num_buffers=3 buffer_size=65535 - -If the driver is compiled into the kernel, at boot time specify them -like this: - -.. code-block:: none - - cpia2.num_buffers=3 cpia2.buffer_size=65535 - -What buffer size should I use? -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -The maximum image size depends on the alternate you choose, and the -frame rate achieved by the camera. If the compression engine is able to -keep up with the frame rate, the maximum image size is given by the table -below. - -The compression engine starts out at maximum compression, and will -increase image quality until it is close to the size in the table. As long -as the compression engine can keep up with the frame rate, after a short time -the images will all be about the size in the table, regardless of resolution. - -At low alternate settings, the compression engine may not be able to -compress the image enough and will reduce the frame rate by producing larger -images. - -The default of 68k should be good for most users. This will handle -any alternate at frame rates down to 15fps. For lower frame rates, it may -be necessary to increase the buffer size to avoid having frames dropped due -to insufficient space. - -========== ========== ======== ===== -Alternate bytes/ms 15fps 30fps -========== ========== ======== ===== - 2 128 8533 4267 - 3 384 25600 12800 - 4 640 42667 21333 - 5 768 51200 25600 - 6 896 59733 29867 - 7 1023 68200 34100 -========== ========== ======== ===== - -Table: Image size(bytes) - - -How many buffers should I use? -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -For normal streaming, 3 should give the best results. With only 2, -it is possible for the camera to finish sending one image just after a -program has started reading the other. If this happens, the driver must drop -a frame. The exception to this is if you have a heavily loaded machine. In -this case use 2 buffers. You are probably not reading at the full frame rate. -If the camera can send multiple images before a read finishes, it could -overwrite the third buffer before the read finishes, leading to a corrupt -image. Single and double buffering have extra checks to avoid overwriting. - -Using the camera -~~~~~~~~~~~~~~~~ - -We are providing a modified gqcam application to view the output. In -order to avoid confusion, here it is called mview. There is also the qx5view -program which can also control the lights on the qx5 microscope. MJPEG Tools -(http://mjpeg.sourceforge.net) can also be used to record from the camera. - -Notes to developers -~~~~~~~~~~~~~~~~~~~ - - - This is a driver version stripped of the 2.4 back compatibility - and old MJPEG ioctl API. See cpia2.sf.net for 2.4 support. - -Programmer's overview of cpia2 driver -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Cpia2 is the second generation video coprocessor from VLSI Vision Ltd (now a -division of ST Microelectronics). There are two versions. The first is the -STV0672, which is capable of up to 30 frames per second (fps) in frame sizes -up to CIF, and 15 fps for VGA frames. The STV0676 is an improved version, -which can handle up to 30 fps VGA. Both coprocessors can be attached to two -CMOS sensors - the vvl6410 CIF sensor and the vvl6500 VGA sensor. These will -be referred to as the 410 and the 500 sensors, or the CIF and VGA sensors. - -The two chipsets operate almost identically. The core is an 8051 processor, -running two different versions of firmware. The 672 runs the VP4 video -processor code, the 676 runs VP5. There are a few differences in register -mappings for the two chips. In these cases, the symbols defined in the -header files are marked with VP4 or VP5 as part of the symbol name. - -The cameras appear externally as three sets of registers. Setting register -values is the only way to control the camera. Some settings are -interdependant, such as the sequence required to power up the camera. I will -try to make note of all of these cases. - -The register sets are called blocks. Block 0 is the system block. This -section is always powered on when the camera is plugged in. It contains -registers that control housekeeping functions such as powering up the video -processor. The video processor is the VP block. These registers control -how the video from the sensor is processed. Examples are timing registers, -user mode (vga, qvga), scaling, cropping, framerates, and so on. The last -block is the video compressor (VC). The video stream sent from the camera is -compressed as Motion JPEG (JPEGA). The VC controls all of the compression -parameters. Looking at the file cpia2_registers.h, you can get a full view -of these registers and the possible values for most of them. - -One or more registers can be set or read by sending a usb control message to -the camera. There are three modes for this. Block mode requests a number -of contiguous registers. Random mode reads or writes random registers with -a tuple structure containing address/value pairs. The repeat mode is only -used by VP4 to load a firmware patch. It contains a starting address and -a sequence of bytes to be written into a gpio port. |