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+$Id: README,v 1.7 2005/08/29 23:39:57 sbertin Exp $
+
+1. 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 separted 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.
+
+2. Making and installing the stv672 driver modules:
+
+        Requirements:
+        -------------
+        This should work with 2.4 (2.4.23 and later) and 2.6 kernels, but has
+only been tested on 2.6.  Video4Linux must be either compiled into the kernel or
+available as a module.  Video4Linux2 is automatically detected and made
+available at compile time.
+
+        Compiling:
+        ----------
+        As root, do a make install.  This will compile and install the modules
+into the media/video directory in the module tree. For 2.4 kernels, use
+Makefile_2.4 (aka do make -f Makefile_2.4 install).
+
+        Setup:
+        ------
+        Use 'modprobe cpia2' to load and 'modprobe -r cpia2' to unload. This
+may be done automatically by your distribution.
+
+3. Driver options
+
+        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:
+        options cpia2 num_buffers=3 buffer_size=65535
+
+        If the driver is compiled into the kernel, at boot time specify them
+like this:
+        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.
+
+                             Image size(bytes)
+        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
+
+        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.
+
+4. 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.
+
+5. 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.
+
+6. Thanks:
+
+   - 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.