mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
![Sylvestre Ledru](/assets/img/avatar_default.png)
Fix some minor typos: * informations => information * there own => their own * these => this Signed-off-by: Sylvestre Ledru <sylvestre.ledru@scilab.org> Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
592 lines
22 KiB
Text
592 lines
22 KiB
Text
|
|
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.
|