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-
- SN9C1xx PC Camera Controllers
- Driver for Linux
- =============================
-
- - Documentation -
-
-
-Index
-=====
-1. Copyright
-2. Disclaimer
-3. License
-4. Overview and features
-5. Module dependencies
-6. Module loading
-7. Module parameters
-8. Optional device control through "sysfs"
-9. Supported devices
-10. Notes for V4L2 application developers
-11. Video frame formats
-12. Contact information
-13. Credits
-
-
-1. Copyright
-============
-Copyright (C) 2004-2007 by Luca Risolia <luca.risolia@studio.unibo.it>
-
-
-2. Disclaimer
-=============
-SONiX is a trademark of SONiX Technology Company Limited, inc.
-This software is not sponsored or developed by SONiX.
-
-
-3. License
-==========
-This program is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2 of the License, or
-(at your option) any later version.
-
-This program is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU General Public License for more details.
-
-You should have received a copy of the GNU General Public License
-along with this program; if not, write to the Free Software
-Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-
-4. Overview and features
-========================
-This driver attempts to support the video interface of the devices assembling
-the SONiX SN9C101, SN9C102, SN9C103, SN9C105 and SN9C120 PC Camera Controllers
-("SN9C1xx" from now on).
-
-The driver relies on the Video4Linux2 and USB core modules. It has been
-designed to run properly on SMP systems as well.
-
-The latest version of the SN9C1xx driver can be found at the following URL:
-http://www.linux-projects.org/
-
-Some of the features of the driver are:
-
-- full compliance with the Video4Linux2 API (see also "Notes for V4L2
- application developers" paragraph);
-- available mmap or read/poll methods for video streaming through isochronous
- data transfers;
-- automatic detection of image sensor;
-- support for built-in microphone interface;
-- support for any window resolutions and optional panning within the maximum
- pixel area of image sensor;
-- image downscaling with arbitrary scaling factors from 1, 2 and 4 in both
- directions (see "Notes for V4L2 application developers" paragraph);
-- two different video formats for uncompressed or compressed data in low or
- high compression quality (see also "Notes for V4L2 application developers"
- and "Video frame formats" paragraphs);
-- full support for the capabilities of many of the possible image sensors that
- can be connected to the SN9C1xx bridges, including, for instance, red, green,
- blue and global gain adjustments and exposure (see "Supported devices"
- paragraph for details);
-- use of default color settings for sunlight conditions;
-- dynamic I/O interface for both SN9C1xx and image sensor control and
- monitoring (see "Optional device control through 'sysfs'" paragraph);
-- dynamic driver control thanks to various module parameters (see "Module
- parameters" paragraph);
-- up to 64 cameras can be handled at the same time; they can be connected and
- disconnected from the host many times without turning off the computer, if
- the system supports hotplugging;
-- no known bugs.
-
-
-5. Module dependencies
-======================
-For it to work properly, the driver needs kernel support for Video4Linux and
-USB.
-
-The following options of the kernel configuration file must be enabled and
-corresponding modules must be compiled:
-
- # Multimedia devices
- #
- CONFIG_VIDEO_DEV=m
-
-To enable advanced debugging functionality on the device through /sysfs:
-
- # Multimedia devices
- #
- CONFIG_VIDEO_ADV_DEBUG=y
-
- # USB support
- #
- CONFIG_USB=m
-
-In addition, depending on the hardware being used, the modules below are
-necessary:
-
- # USB Host Controller Drivers
- #
- CONFIG_USB_EHCI_HCD=m
- CONFIG_USB_UHCI_HCD=m
- CONFIG_USB_OHCI_HCD=m
-
-The SN9C103, SN9c105 and SN9C120 controllers also provide a built-in microphone
-interface. It is supported by the USB Audio driver thanks to the ALSA API:
-
- # Sound
- #
- CONFIG_SOUND=y
-
- # Advanced Linux Sound Architecture
- #
- CONFIG_SND=m
-
- # USB devices
- #
- CONFIG_SND_USB_AUDIO=m
-
-And finally:
-
- # USB Multimedia devices
- #
- CONFIG_USB_SN9C102=m
-
-
-6. Module loading
-=================
-To use the driver, it is necessary to load the "sn9c102" module into memory
-after every other module required: "videodev", "v4l2_common", "compat_ioctl32",
-"usbcore" and, depending on the USB host controller you have, "ehci-hcd",
-"uhci-hcd" or "ohci-hcd".
-
-Loading can be done as shown below:
-
- [root@localhost home]# modprobe sn9c102
-
-Note that the module is called "sn9c102" for historic reasons, although it
-does not just support the SN9C102.
-
-At this point all the devices supported by the driver and connected to the USB
-ports should be recognized. You can invoke "dmesg" to analyze kernel messages
-and verify that the loading process has gone well:
-
- [user@localhost home]$ dmesg
-
-or, to isolate all the kernel messages generated by the driver:
-
- [user@localhost home]$ dmesg | grep sn9c102
-
-
-7. Module parameters
-====================
-Module parameters are listed below:
--------------------------------------------------------------------------------
-Name: video_nr
-Type: short array (min = 0, max = 64)
-Syntax: <-1|n[,...]>
-Description: Specify V4L2 minor mode number:
- -1 = use next available
- n = use minor number n
- You can specify up to 64 cameras this way.
- For example:
- video_nr=-1,2,-1 would assign minor number 2 to the second
- recognized camera and use auto for the first one and for every
- other camera.
-Default: -1
--------------------------------------------------------------------------------
-Name: force_munmap
-Type: bool array (min = 0, max = 64)
-Syntax: <0|1[,...]>
-Description: Force the application to unmap previously mapped buffer memory
- before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
- all the applications support this feature. This parameter is
- specific for each detected camera.
- 0 = do not force memory unmapping
- 1 = force memory unmapping (save memory)
-Default: 0
--------------------------------------------------------------------------------
-Name: frame_timeout
-Type: uint array (min = 0, max = 64)
-Syntax: <0|n[,...]>
-Description: Timeout for a video frame in seconds before returning an I/O
- error; 0 for infinity. This parameter is specific for each
- detected camera and can be changed at runtime thanks to the
- /sys filesystem interface.
-Default: 2
--------------------------------------------------------------------------------
-Name: debug
-Type: ushort
-Syntax: <n>
-Description: Debugging information level, from 0 to 3:
- 0 = none (use carefully)
- 1 = critical errors
- 2 = significant information
- 3 = more verbose messages
- Level 3 is useful for testing only. It also shows some more
- information about the hardware being detected.
- This parameter can be changed at runtime thanks to the /sys
- filesystem interface.
-Default: 2
--------------------------------------------------------------------------------
-
-
-8. Optional device control through "sysfs" [1]
-==========================================
-If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled,
-it is possible to read and write both the SN9C1xx and the image sensor
-registers by using the "sysfs" filesystem interface.
-
-Every time a supported device is recognized, a write-only file named "green" is
-created in the /sys/class/video4linux/videoX directory. You can set the green
-channel's gain by writing the desired value to it. The value may range from 0
-to 15 for the SN9C101 or SN9C102 bridges, from 0 to 127 for the SN9C103,
-SN9C105 and SN9C120 bridges.
-Similarly, only for the SN9C103, SN9C105 and SN9C120 controllers, blue and red
-gain control files are available in the same directory, for which accepted
-values may range from 0 to 127.
-
-There are other four entries in the directory above for each registered camera:
-"reg", "val", "i2c_reg" and "i2c_val". The first two files control the
-SN9C1xx bridge, while the other two control the sensor chip. "reg" and
-"i2c_reg" hold the values of the current register index where the following
-reading/writing operations are addressed at through "val" and "i2c_val". Their
-use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not
-be created if the sensor does not actually support the standard I2C protocol or
-its registers are not 8-bit long. Also, remember that you must be logged in as
-root before writing to them.
-
-As an example, suppose we were to want to read the value contained in the
-register number 1 of the sensor register table - which is usually the product
-identifier - of the camera registered as "/dev/video0":
-
- [root@localhost #] cd /sys/class/video4linux/video0
- [root@localhost #] echo 1 > i2c_reg
- [root@localhost #] cat i2c_val
-
-Note that "cat" will fail if sensor registers cannot be read.
-
-Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2:
-
- [root@localhost #] echo 0x11 > reg
- [root@localhost #] echo 2 > val
-
-Note that the SN9C1xx always returns 0 when some of its registers are read.
-To avoid race conditions, all the I/O accesses to the above files are
-serialized.
-The sysfs interface also provides the "frame_header" entry, which exports the
-frame header of the most recent requested and captured video frame. The header
-is always 18-bytes long and is appended to every video frame by the SN9C1xx
-controllers. As an example, this additional information can be used by the user
-application for implementing auto-exposure features via software.
-
-The following table describes the frame header exported by the SN9C101 and
-SN9C102:
-
-Byte # Value or bits Description
------- ------------- -----------
-0x00 0xFF Frame synchronisation pattern
-0x01 0xFF Frame synchronisation pattern
-0x02 0x00 Frame synchronisation pattern
-0x03 0xC4 Frame synchronisation pattern
-0x04 0xC4 Frame synchronisation pattern
-0x05 0x96 Frame synchronisation pattern
-0x06 [3:0] Read channel gain control = (1+R_GAIN/8)
- [7:4] Blue channel gain control = (1+B_GAIN/8)
-0x07 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled
- [2:1] Maximum scale factor for compression
- [ 3 ] 1 = USB fifo(2K bytes) is full
- [ 4 ] 1 = Digital gain is finish
- [ 5 ] 1 = Exposure is finish
- [7:6] Frame index
-0x08 [7:0] Y sum inside Auto-Exposure area (low-byte)
-0x09 [7:0] Y sum inside Auto-Exposure area (high-byte)
- where Y sum = (R/4 + 5G/16 + B/8) / 32
-0x0A [7:0] Y sum outside Auto-Exposure area (low-byte)
-0x0B [7:0] Y sum outside Auto-Exposure area (high-byte)
- where Y sum = (R/4 + 5G/16 + B/8) / 128
-0x0C 0xXX Not used
-0x0D 0xXX Not used
-0x0E 0xXX Not used
-0x0F 0xXX Not used
-0x10 0xXX Not used
-0x11 0xXX Not used
-
-The following table describes the frame header exported by the SN9C103:
-
-Byte # Value or bits Description
------- ------------- -----------
-0x00 0xFF Frame synchronisation pattern
-0x01 0xFF Frame synchronisation pattern
-0x02 0x00 Frame synchronisation pattern
-0x03 0xC4 Frame synchronisation pattern
-0x04 0xC4 Frame synchronisation pattern
-0x05 0x96 Frame synchronisation pattern
-0x06 [6:0] Read channel gain control = (1/2+R_GAIN/64)
-0x07 [6:0] Blue channel gain control = (1/2+B_GAIN/64)
- [7:4]
-0x08 [ 0 ] Compression mode. 0=No compression, 1=Compression enabled
- [2:1] Maximum scale factor for compression
- [ 3 ] 1 = USB fifo(2K bytes) is full
- [ 4 ] 1 = Digital gain is finish
- [ 5 ] 1 = Exposure is finish
- [7:6] Frame index
-0x09 [7:0] Y sum inside Auto-Exposure area (low-byte)
-0x0A [7:0] Y sum inside Auto-Exposure area (high-byte)
- where Y sum = (R/4 + 5G/16 + B/8) / 32
-0x0B [7:0] Y sum outside Auto-Exposure area (low-byte)
-0x0C [7:0] Y sum outside Auto-Exposure area (high-byte)
- where Y sum = (R/4 + 5G/16 + B/8) / 128
-0x0D [1:0] Audio frame number
- [ 2 ] 1 = Audio is recording
-0x0E [7:0] Audio summation (low-byte)
-0x0F [7:0] Audio summation (high-byte)
-0x10 [7:0] Audio sample count
-0x11 [7:0] Audio peak data in audio frame
-
-The AE area (sx, sy, ex, ey) in the active window can be set by programming the
-registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C1xx controllers, where one unit
-corresponds to 32 pixels.
-
-[1] The frame headers exported by the SN9C105 and SN9C120 are not described.
-
-
-9. Supported devices
-====================
-None of the names of the companies as well as their products will be mentioned
-here. They have never collaborated with the author, so no advertising.
-
-From the point of view of a driver, what unambiguously identify a device are
-its vendor and product USB identifiers. Below is a list of known identifiers of
-devices assembling the SN9C1xx PC camera controllers:
-
-Vendor ID Product ID
---------- ----------
-0x0458 0x7025
-0x045e 0x00f5
-0x045e 0x00f7
-0x0471 0x0327
-0x0471 0x0328
-0x0c45 0x6001
-0x0c45 0x6005
-0x0c45 0x6007
-0x0c45 0x6009
-0x0c45 0x600d
-0x0c45 0x6011
-0x0c45 0x6019
-0x0c45 0x6024
-0x0c45 0x6025
-0x0c45 0x6028
-0x0c45 0x6029
-0x0c45 0x602a
-0x0c45 0x602b
-0x0c45 0x602c
-0x0c45 0x602d
-0x0c45 0x602e
-0x0c45 0x6030
-0x0c45 0x603f
-0x0c45 0x6080
-0x0c45 0x6082
-0x0c45 0x6083
-0x0c45 0x6088
-0x0c45 0x608a
-0x0c45 0x608b
-0x0c45 0x608c
-0x0c45 0x608e
-0x0c45 0x608f
-0x0c45 0x60a0
-0x0c45 0x60a2
-0x0c45 0x60a3
-0x0c45 0x60a8
-0x0c45 0x60aa
-0x0c45 0x60ab
-0x0c45 0x60ac
-0x0c45 0x60ae
-0x0c45 0x60af
-0x0c45 0x60b0
-0x0c45 0x60b2
-0x0c45 0x60b3
-0x0c45 0x60b8
-0x0c45 0x60ba
-0x0c45 0x60bb
-0x0c45 0x60bc
-0x0c45 0x60be
-0x0c45 0x60c0
-0x0c45 0x60c2
-0x0c45 0x60c8
-0x0c45 0x60cc
-0x0c45 0x60ea
-0x0c45 0x60ec
-0x0c45 0x60ef
-0x0c45 0x60fa
-0x0c45 0x60fb
-0x0c45 0x60fc
-0x0c45 0x60fe
-0x0c45 0x6102
-0x0c45 0x6108
-0x0c45 0x610f
-0x0c45 0x6130
-0x0c45 0x6138
-0x0c45 0x613a
-0x0c45 0x613b
-0x0c45 0x613c
-0x0c45 0x613e
-
-The list above does not imply that all those devices work with this driver: up
-until now only the ones that assemble the following pairs of SN9C1xx bridges
-and image sensors are supported; kernel messages will always tell you whether
-this is the case (see "Module loading" paragraph):
-
-Image sensor / SN9C1xx bridge | SN9C10[12] SN9C103 SN9C105 SN9C120
--------------------------------------------------------------------------------
-HV7131D Hynix Semiconductor | Yes No No No
-HV7131R Hynix Semiconductor | No Yes Yes Yes
-MI-0343 Micron Technology | Yes No No No
-MI-0360 Micron Technology | No Yes Yes Yes
-OV7630 OmniVision Technologies | Yes Yes Yes Yes
-OV7660 OmniVision Technologies | No No Yes Yes
-PAS106B PixArt Imaging | Yes No No No
-PAS202B PixArt Imaging | Yes Yes No No
-TAS5110C1B Taiwan Advanced Sensor | Yes No No No
-TAS5110D Taiwan Advanced Sensor | Yes No No No
-TAS5130D1B Taiwan Advanced Sensor | Yes No No No
-
-"Yes" means that the pair is supported by the driver, while "No" means that the
-pair does not exist or is not supported by the driver.
-
-Only some of the available control settings of each image sensor are supported
-through the V4L2 interface.
-
-Donations of new models for further testing and support would be much
-appreciated. Non-available hardware will not be supported by the author of this
-driver.
-
-
-10. Notes for V4L2 application developers
-=========================================
-This driver follows the V4L2 API specifications. In particular, it enforces two
-rules:
-
-- exactly one I/O method, either "mmap" or "read", is associated with each
-file descriptor. Once it is selected, the application must close and reopen the
-device to switch to the other I/O method;
-
-- although it is not mandatory, previously mapped buffer memory should always
-be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's.
-The same number of buffers as before will be allocated again to match the size
-of the new video frames, so you have to map the buffers again before any I/O
-attempts on them.
-
-Consistently with the hardware limits, this driver also supports image
-downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions.
-However, the V4L2 API specifications don't correctly define how the scaling
-factor can be chosen arbitrarily by the "negotiation" of the "source" and
-"target" rectangles. To work around this flaw, we have added the convention
-that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the
-scaling factor is restored to 1.
-
-This driver supports two different video formats: the first one is the "8-bit
-Sequential Bayer" format and can be used to obtain uncompressed video data
-from the device through the current I/O method, while the second one provides
-either "raw" compressed video data (without frame headers not related to the
-compressed data) or standard JPEG (with frame headers). The compression quality
-may vary from 0 to 1 and can be selected or queried thanks to the
-VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's. For maximum flexibility,
-both the default active video format and the default compression quality
-depend on how the image sensor being used is initialized.
-
-
-11. Video frame formats [1]
-=======================
-The SN9C1xx PC Camera Controllers can send images in two possible video
-formats over the USB: either native "Sequential RGB Bayer" or compressed.
-The compression is used to achieve high frame rates. With regard to the
-SN9C101, SN9C102 and SN9C103, the compression is based on the Huffman encoding
-algorithm described below, while with regard to the SN9C105 and SN9C120 the
-compression is based on the JPEG standard.
-The current video format may be selected or queried from the user application
-by calling the VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2
-API specifications.
-
-The name "Sequential Bayer" indicates the organization of the red, green and
-blue pixels in one video frame. Each pixel is associated with a 8-bit long
-value and is disposed in memory according to the pattern shown below:
-
-B[0] G[1] B[2] G[3] ... B[m-2] G[m-1]
-G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1]
-...
-... B[(n-1)(m-2)] G[(n-1)(m-1)]
-... G[n(m-2)] R[n(m-1)]
-
-The above matrix also represents the sequential or progressive read-out mode of
-the (n, m) Bayer color filter array used in many CCD or CMOS image sensors.
-
-The Huffman compressed video frame consists of a bitstream that encodes for
-every R, G, or B pixel the difference between the value of the pixel itself and
-some reference pixel value. Pixels are organised in the Bayer pattern and the
-Bayer sub-pixels are tracked individually and alternatingly. For example, in
-the first line values for the B and G1 pixels are alternatingly encoded, while
-in the second line values for the G2 and R pixels are alternatingly encoded.
-
-The pixel reference value is calculated as follows:
-- the 4 top left pixels are encoded in raw uncompressed 8-bit format;
-- the value in the top two rows is the value of the pixel left of the current
- pixel;
-- the value in the left column is the value of the pixel above the current
- pixel;
-- for all other pixels, the reference value is the average of the value of the
- pixel on the left and the value of the pixel above the current pixel;
-- there is one code in the bitstream that specifies the value of a pixel
- directly (in 4-bit resolution);
-- pixel values need to be clamped inside the range [0..255] for proper
- decoding.
-
-The algorithm purely describes the conversion from compressed Bayer code used
-in the SN9C101, SN9C102 and SN9C103 chips to uncompressed Bayer. Additional
-steps are required to convert this to a color image (i.e. a color interpolation
-algorithm).
-
-The following Huffman codes have been found:
-0: +0 (relative to reference pixel value)
-100: +4
-101: -4?
-1110xxxx: set absolute value to xxxx.0000
-1101: +11
-1111: -11
-11001: +20
-110000: -20
-110001: ??? - these codes are apparently not used
-
-[1] The Huffman compression algorithm has been reverse-engineered and
- documented by Bertrik Sikken.
-
-
-12. Contact information
-=======================
-The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
-
-GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
-'FCE635A4'; the public 1024-bit key should be available at any keyserver;
-the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
-
-
-13. Credits
-===========
-Many thanks to following persons for their contribute (listed in alphabetical
-order):
-
-- David Anderson for the donation of a webcam;
-- Luca Capello for the donation of a webcam;
-- Philippe Coval for having helped testing the PAS202BCA image sensor;
-- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the
- donation of a webcam;
-- Dennis Heitmann for the donation of a webcam;
-- Jon Hollstrom for the donation of a webcam;
-- Nick McGill for the donation of a webcam;
-- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB
- image sensor;
-- Stefano Mozzi, who donated 45 EU;
-- Andrew Pearce for the donation of a webcam;
-- John Pullan for the donation of a webcam;
-- Bertrik Sikken, who reverse-engineered and documented the Huffman compression
- algorithm used in the SN9C101, SN9C102 and SN9C103 controllers and
- implemented the first decoder;
-- Ronny Standke for the donation of a webcam;
-- Mizuno Takafumi for the donation of a webcam;
-- an "anonymous" donator (who didn't want his name to be revealed) for the
- donation of a webcam.
-- an anonymous donator for the donation of four webcams and two boards with ten
- image sensors.