1. Copyright
2. Disclaimer
3. License
-4. Overview
-5. Driver installation
+4. Overview and features
+5. Module dependencies
6. Module loading
7. Module parameters
8. Optional device control through "sysfs"
9. Supported devices
-10. How to add support for new image sensors
-11. Notes for V4L2 application developers
+10. Notes for V4L2 application developers
+11. Video frame formats
12. Contact information
13. Credits
1. Copyright
============
-Copyright (C) 2004 by Luca Risolia <luca.risolia@studio.unibo.it>
+Copyright (C) 2004-2006 by Luca Risolia <luca.risolia@studio.unibo.it>
2. Disclaimer
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-4. Overview
-===========
-This driver attempts to support the video and audio streaming capabilities of
-the devices mounting the SONiX SN9C101, SN9C102 and SN9C103 (or SUI-102) PC
-Camera Controllers.
+4. Overview and features
+========================
+This driver attempts to support the video interface of the devices mounting the
+SONiX SN9C101, SN9C102 and SN9C103 PC Camera Controllers.
It's worth to note that SONiX has never collaborated with the author during the
development of this project, despite several requests for enough detailed
specifications of the register tables, compression engine and video data format
-of the above chips.
+of the above chips. Nevertheless, these informations are no longer necessary,
+becouse all the aspects related to these chips are known and have been
+described in detail in this documentation.
The driver relies on the Video4Linux2 and USB core modules. It has been
designed to run properly on SMP systems as well.
- 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 (see also
- "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 SN9C10x bridges, including, for istance, 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 SN9C10x and image sensor control (see
- "Optional device control through 'sysfs'" paragraph);
+- dynamic I/O interface for both SN9C10x 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
- your system supports hotplugging;
+ the system supports hotplugging;
- no known bugs.
#
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
CONFIG_USB_UHCI_HCD=m
CONFIG_USB_OHCI_HCD=m
+The SN9C103 controller also provides 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
Module parameters are listed below:
-------------------------------------------------------------------------------
Name: video_nr
-Type: int array (min = 0, max = 64)
+Type: short array (min = 0, max = 64)
Syntax: <-1|n[,...]>
Description: Specify V4L2 minor mode number:
-1 = use next available
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: debug
-Type: int
+Type: ushort
Syntax: <n>
Description: Debugging information level, from 0 to 3:
0 = none (use carefully)
Level 3 is useful for testing only, when only one device
is used. It also shows some more informations about the
hardware being detected. This parameter can be changed at
- runtime thanks to the /sys filesystem.
+ runtime thanks to the /sys filesystem interface.
Default: 2
-------------------------------------------------------------------------------
-8. Optional device control through "sysfs"
+8. Optional device control through "sysfs" [1]
==========================================
-It is possible to read and write both the SN9C10x and the image sensor
+If the kernel has been compiled with the CONFIG_VIDEO_ADV_DEBUG option enabled,
+it is possible to read and write both the SN9C10x 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
SN9C10x 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, unless you know what you are doing. Note
-that "i2c_reg" and "i2c_val" won't be created if the sensor does not actually
-support the standard I2C protocol. Also, remember that you must be logged in as
+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
[root@localhost #] echo 2 > val
Note that the SN9C10x always returns 0 when some of its registers are read.
-To avoid race conditions, all the I/O accesses to the files are serialized.
+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 SN9C10x
+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:
+
+Byte # Value 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 0xXX Unknown meaning. The exact value depends on the chip;
+ possible values are 0x00, 0x01 and 0x20.
+0x07 0xXX Variable value, whose bits are ff00uzzc, where ff is a
+ frame counter, u is unknown, zz is a size indicator
+ (00 = VGA, 01 = SIF, 10 = QSIF) and c stands for
+ "compression enabled" (1 = yes, 0 = no).
+0x08 0xXX Brightness sum inside Auto-Exposure area (low-byte).
+0x09 0xXX Brightness sum inside Auto-Exposure area (high-byte).
+ For a pure white image, this number will be equal to 500
+ times the area of the specified AE area. For images
+ that are not pure white, the value scales down according
+ to relative whiteness.
+0x0A 0xXX Brightness sum outside Auto-Exposure area (low-byte).
+0x0B 0xXX Brightness sum outside Auto-Exposure area (high-byte).
+ For a pure white image, this number will be equal to 125
+ times the area outside of the specified AE area. For
+ images that are not pure white, the value scales down
+ according to relative whiteness.
+ according to relative whiteness.
+
+The following bytes are used by the SN9C103 bridge only:
+
+0x0C 0xXX Unknown meaning
+0x0D 0xXX Unknown meaning
+0x0E 0xXX Unknown meaning
+0x0F 0xXX Unknown meaning
+0x10 0xXX Unknown meaning
+0x11 0xXX Unknown meaning
+
+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 SN9C10x controllers, where one unit
+corresponds to 32 pixels.
+
+[1] Part of the meaning of the frame header has been documented by Bertrik
+ Sikken.
9. Supported devices
0x0c45 0x602a
0x0c45 0x602b
0x0c45 0x602c
+0x0c45 0x602d
+0x0c45 0x602e
0x0c45 0x6030
0x0c45 0x6080
0x0c45 0x6082
Model Manufacturer
----- ------------
-PAS106B PixArt Imaging Inc.
-PAS202BCB PixArt Imaging Inc.
+HV7131D Hynix Semiconductor, Inc.
+MI-0343 Micron Technology, Inc.
+OV7630 OmniVision Technologies, Inc.
+PAS106B PixArt Imaging, Inc.
+PAS202BCB PixArt Imaging, Inc.
TAS5110C1B Taiwan Advanced Sensor Corporation
TAS5130D1B Taiwan Advanced Sensor Corporation
All the available control settings of each image sensor are supported through
the V4L2 interface.
-If you think your camera is based on the above hardware and is not actually
-listed in the above table, you may try to add the specific USB VendorID and
-ProductID identifiers to the sn9c102_id_table[] in the file "sn9c102_sensor.h";
-then compile, load the module again and look at the kernel output.
-If this works, please send an email to the author reporting the kernel
-messages, so that a new entry in the list of supported devices can be added.
-
Donations of new models for further testing and support would be much
-appreciated. Non-available hardware won't be supported by the author of this
+appreciated. Non-available hardware will not be supported by the author of this
driver.
-10. How to add support for new image sensors
-============================================
-It should be easy to write code for new sensors by using the small API that I
-have created for this purpose, which is present in "sn9c102_sensor.h"
-(documentation is included there). As an example, have a look at the code in
-"sn9c102_pas106b.c", which uses the mentioned interface.
-
-At the moment, possible unsupported image sensors are: HV7131x series (VGA),
-MI03x series (VGA), OV7620 (VGA), OV7630 (VGA), CIS-VF10 (VGA).
-
-
-11. Notes for V4L2 application developers
+10. Notes for V4L2 application developers
=========================================
This driver follows the V4L2 API specifications. In particular, it enforces two
rules:
file descriptor. Once it is selected, the application must close and reopen the
device to switch to the other I/O method;
-- previously mapped buffer memory must always be unmapped before calling any
-of the "VIDIOC_S_CROP", "VIDIOC_TRY_FMT" and "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.
+- 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.
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
-"raw" compressed video data (without the initial and final 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, the default active video format depends on how the image sensor
-being used is initialized (as described in the documentation of the API for the
-image sensors supplied by this driver).
+"raw" compressed video data (without frame headers not related to the
+compressed data). 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 (as described in the documentation of the API for the image sensors
+supplied by this driver).
+
+
+11. Video frame formats [1]
+=======================
+The SN9C10x PC Camera Controllers can send images in two possible video
+formats over the USB: either native "Sequential RGB Bayer" or Huffman
+compressed. The latter is used to achieve high frame rates. 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/CMOS image sensors.
+
+One 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 SN9C10x 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
=======================
-I may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
+The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
-I can accept GPG/PGP encrypted e-mail. My GPG key ID is 'FCE635A4'.
-My public 1024-bit key should be available at any keyserver; the fingerprint
-is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
+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
===========
-I would thank the following persons:
+Many thanks to following persons for their contribute (listed in alphabetical
+order):
-- Stefano Mozzi, who donated 45 EU;
- Luca Capello for the donation of a webcam;
-- Mizuno Takafumi for the donation of a webcam;
+- Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the
+ donation of a webcam;
+- Jon Hollstrom for the donation of a webcam;
- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB
- image sensor.
+ image sensor;
+- Stefano Mozzi, who donated 45 EU;
+- Andrew Pearce for the donation of a webcam;
+- Bertrik Sikken, who reverse-engineered and documented the Huffman compression
+ algorithm used in the SN9C10x controllers and implemented the first decoder;
+- 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.
git://git.onelab.eu / linux-2.6.git / blobdiff