|Coriander : Manual|
(This is a very rough HTMLization of the TeX manual that can be downloaded on the SourceForge website).
What is Coriander
Coriander is a Graphical User Interface (GUI) for controlling an IEEE1394 camera. This camera should be compliant with the Industrial and Instrumentation Digital Camera (IIDC) specifications, as issued by the 1394 Trade Association. These specifications are aimed at industrial and scientific cameras, as their name would suggest. IIDC is not for commercial grade camcorders, and Coriander will thus not work with any camera in which you can insert a tape. Note that IEEE1394 webcams are most of the time compliant with the IIDC specs.
About this manual
This manual is just a draft written in one rainy afternoon to help you go through the controls of Coriander. It is incomplete, very drafty, full of typos and mistakes, and last but no least is probably full of technical errors. You re welcome to contribute to it if you want to make it any better. Besides this manual you might also want to read the IIDC specs, which is probably the best thing to do to learn how to control your camera.
IIDC vs. DV
You should keep in mind that DV camcorders compress the video before sending it so that you must decompress the video in the host computer before you can use it. This compression occurs because the video files would be otherwise much too large for a computer to deal with. Even with today's big harddrives the problem remains as one hour of video would take as much as a whole 100GB hard drive (720x576x3x25x3600).
IIDC cameras, on the other hand, do not compress video. This results in a much higher bandwidth: DV is typically less than 20Mb/s while a typical VGA webcam will need around 100Mb/s on the bus. This could be seen as a drawback for IIDC cams, but it is also their advantage: since no compression occur in the camera, no decompression is required in the host computer which can be fully used for other tasks. This is the reason while most real-time applications, common in the industrial and scientific world, will use IIDC cameras.
The hardware requirements a very simple: you need a Linux box, an IIDC compliant IEEE1394 camera and an interface card. I strongly advise you choose an OHCI interface, for their support is better under Linux. Moreover, capturing images with DMA is only available for this class of interfaces.
The compliance of the camera with IIDC is not always marked on the datasheets, and it is sometimes difficult to tell before actually buying the camera. There is a webpage describing all the 1394 cameras, I suggest you have a look at it.
This is where the serious fun begins... Although the only required thing is a 1394- enabled Linux kernel, I will spend some lines describing the problems you might have. If you have weird things happening with your kernel you should visit the linux1394 project.
Something important regarding libraries: you should check that the path /usr/local/lib is in the file /etc/ld.so.conf. You will have to add this path on some distributions, notably Red Hat. In order for the library database to include the newly installed libs, ldconfig is automatically run during each library installation. However, if the path mentioned above was not there, ldconfig will not have taken the new libs into account and you will have to run it after adding the /usr/local/lib path.
Linux Kernel and devices
It is strongly advised to use a recent kernel. In the 2.4 branch choose 2.4.23 or later, for the 2.6 branch try 2.6.11. There has been recent changes in the DMA kernel API so that coriander and libdc1394 will only compile with a kernel version >=2.4.23. You should enable 1394 support and select raw1394, ohci1394 (or pcilynx, depending on your card) and video1394 modules (for DMA, only works with OHCI cards). Do not enable excessive debugging output as this will result in printing a debug line for each command sent on the bus. This obviously slows things down quite a bit.
After compiling and installing the modules, you should create the proper 1394 devices. There are two devices to create: raw1394 and video1394. raw1394 has major 171 and minor 0, while video1394 had major 171 and minor 16. If you use several interface cards you need one video1394 device per card. The standard way to do this is to create a video1394 directory (instead of a device), and create the first device (171,16), second device (171,17),... in that directory. The names for these devices is usually simply 0,1,2,...
As Coriander is a Gnome 2 application, I expect you to have some Gnome libraries installed. Besides the main Gnome library, you should also install the Gnome development packages and libraries. If the development libraries are not installed the configure script will fail with some message related to gnome-config.
Side note: Coriander was a Gnome 1.4 application until version 1.1.0. If you have an older version you will need all Gnome 1.4 stuff.
Misc building libraries
Autoconf and Automake are required if you are building Coriander from CVS or for older versions of Coriander (before 0.99.4). This is usually part of your favorite distibution but you might need an update.
You should download libraw1394 and install it. There is nothing really special for this library. Just use a recent version (>= 0.9.0)for there might be some compatibility problems. This library is probed in the configure script so that if you don't have a recent version you will be prompted for a download.
libdc1394 is the IIDC API so it's really mandatory... Use the latest version; it is even recommended to use the CVS since Coriander sticks to libdc1394 and is updated very regularly. If you don't have a sufficiently recent version the configure script will fail and ask you for an update.
If you wish to use the FTP capabilities of Coriander you need libftp . This library is thus not necessary; it's an option. Download and install the library in the usual way as described in the library README file. It might be available as a package for your distribution.
One of the major feature of Coriander is its live display. This function requires the SDL library. You should simply install the library on your computer, using your distribution packages. I can't think of a distribution without SDL so you won t have problems to find it.
The vloopback interface is a kernel module which can be used to export video through a V4L device. It elegantly changes Coriander into a V4L source that can be further used by applications like Effectv or Gnomemeeting.
The installation is fairly easy: just run ./configure (or sh autogen.sh if you use the CVS version) and type make to build the program. If you want a systemwide installation you can make install , which requires root privileges. If you encounter compilation problems you can post a bug report on the SourceForge website.
In order to launch Coriander, you should first install the kernel modules. You can insert this in the /etc/rc.local file (RedHat systems) or in the /etc/rc.boot directory (Debian) to launch the modules at every boot. Other file modifications might be required on other distributions.
First modprobe ieee1394 raw1394 ohci1394 video1394. Once the modules have been loaded, plug a camera in the 1394 port of you computer. Check that the bus is powered and launch Coriander. Two things can happen now.
One possibility is that everything goes well and you have the Coriander main control window on the screen. This is good. You can now play with the camera controls described in the next section.
Some things could go wrong, in which case Coriander will give you a message with a guess about the problem and how to fix it. Check that every item proposed is OK, correct your setup and retry. Send a bug-report if you still have problems. If you want to see what's on the IEEE1394 bus for low-level debugging purposes you can have a look at gscanbus.
The IIDC standard
This is just a short presentation of the standard, you can obtain a copy of it on the 1394 Trade Association website. Unfortunately, the 1394-TA now asks money simply to send you a PDF, so you might as well send me an email to get a free copy. If copyright allows, I will put a version of this document on Coriander homepage too. The current version of IIDC is 1.31. It is the one described here. The IIDC standard can be split in several sections:
Some image formats like Format_7 and Format_6 have a specific set of commands that are also described.
Coriander almost fully implements the controls of the IIDC specifications. The IIDC specs do not say that your camera should provide every possible control, but merely that it should implement some of them. Coriander can read what is supported by your camera and allows you to control what can be controlled. For example, if the Iris feature is not available in your camera, it won't be shown. If the format/mode you have select does not support 30fps, you won't be able to choose that. If you re camera can't be powered off, the power control will be inactive.
Features are actually image controls provided by the camera. The full list of feature is: Brightness, Auto Exposure, Sharpness, White Balance, Hue, Saturation, Gamma, Shutter, Gain, Iris, Focus, Temperature, Trigger, Trigger Delay, White Shading, Frame Rate, Zoom, Pan, Tilt, Optical Filter, Capture Size and Capture Quality.
You will find a detailed explanation about each one in the IIDC specifications, but I guess you already have an idea about what is their respective purpose. Features have several controls available:
Two features have two values associated to them: the temperature feature (current temperature, target temperature) and the white balance (the two colour channels). At last, the trigger feature is completely different and you will find details about it in the IIDC specifications.
Image formats are defined by two parameters: the Format and the Mode, each Format containing several modes. Five modes are defined in IIDC:
The IIDC specifications provide many more controls. Instead of providing a pale copy of the standard here, the next section will review the GUI controls one by one. This will show you the particularities of the GUI and how to use it. If you plan to make your own programs using libdc1394, you should read the IIDC specs (but you did that anyway, didn't you?).
The Graphical User Interface
The main menu contains only two pop-down menus: the File and Help menus. The File menu leads to the preferences window and the exit. The Help menu leads to the classic About window and to a description of the keyboard shortcuts for the display. These shortcuts will be explained in the display section, so that only the preferences window need to be addressed here.
The preferences window contains two controls:
These two controls, as well as several other user options like text inputs, camera nicknames,... are saved into a preference file in /.gnome/coriander.
That's all for the main window controls. The other controls are located in tabs and are described below.
The Camera Tab
This tab contains the general camera controls, as well as a camera selector.
The camera information box is a summary of the low-level ROM:
The Services Tab
Services are processes that can be launched and cancelled using the buttons in the Switch/FPS box. This box also provides an estimate of the image rate for each service, in frames per second.
Introduction to the service system
Coriander provides a number of image services . This smart (hey! I designed that! ;-) ) system is a kind of pipeline for images: these travel from left to right (receive > display > save > V4L > FTP) and are used successively by different processes, implemented as threads. If you re really interested in this kind of thing you should pay a visit to the code, but I would like to stress some things that will be useful for everybody to know.
First, as stated above, the images travel from left to right (look at the Switch box). Services have been ordered on this queue with respect to their expected speed: fast services before slow ones. This is because the pipe structure can create frame dropping. As images are sent to the next service after being used by the current service, the output framerate of a service is equal to the framerate of the service or its input framerate, whichever is smaller. This results in the fact that the service framerates will be decreasing from left to right. You can easily check that by looking at the framerate displays under each service button.
Technically, each service contains at least two image buffers: an input buffer and an output buffer. When a service finished working on an image, the image is put on its output buffer and a flag is set. The following service, seeing the new frame flag , exchanges the pointer of its input buffer with the pointer of the output buffer of the previous service. Images propagate that way from left to right, while used buffers propagate the other way back to the first service. Each service being a separate thread, this process is completely asynchronous.
If you change the image size (e.g. by changing mode or format), used buffers will be re-allocated when they return to the receive service, which is the only one to allocate image buffers. At last, buffers contain all the information about the image: size, colour coding,... so that each service checks the buffer for changes and adapt itself automatically if necessary. That also means that if no frames have been received yet, the service is not activated (it does not know the image size,...). Example: no display window show up until you actually received one frame.
A quick but important note here: in order to get an image from the camera you have to push three buttons: start the receive service, start the display service and start the ISO transmission. The order does not matter but you have to push the three buttons.
The Receive Service
The receive service tab not only contains specific Linux/Coriander controls but also IIDC controls like image format. It seemed just right to put the latter there, so there they are.
Note that some images include padding, particularly with Format_7. This padding is conserved during the whole process if there is no other image processing required (RAW save, no bayer or stereo conversion,...) It is important to know the padding value when you save in RAW mode so that I advise you write down the padding value displayed in the camera tab.
The Display Service
The display service tab has not many features, but more capabilities are directly handled by SDL.
When the display window is the active window you can use mouse and keyboard controls to change some display parameters, as well as Format_7 parameters. Functions are (see the Help/Key bindings menu):
Note that you really should have an accelerated display card to show images efficiently. Try xvinfo to see if your video card supports overlay. If you have a huge output, it's OK. If just get 3-4 lines, you should install better drivers. For nVidia cards, have a look at the nVidia website, for ATI users check the Gatos project or the ATI website.
The Save Service
The save service is for saving image (or image sequences) to a disk. The disk can be local or remote, but of course remote disks will have lower performances.
The V4L Service
This service sends frame to the selected video4linux device. The vloopback kernel module will then forward the frames to the next V4L device. Other apps may use the latter device to get images from Coriander. Important note: there is always a +1 difference between the V4L device you mention in the output device box and the device that will be used by other apps. Example: if Coriander videodev is /dev/video0, gnomemeeting will use /dev/video1.
The FTP service
This service send images to a remote computer using the FTP protocol.
The Format_7 Tab
The Format_7 tab is only available with cameras that support Format_7. With this tab you select all Format_7 parameters for every mode. You can change Format_7 parameters of a mode which is not the selected (i.e. streaming) one. The mode you are editing is automatically set to the current mode when this mode is changed.
The Status Tab
The Cursor box contains info about the location and the colour content of the pixel under the mouse pointer (see display service). At last, a message window shows error and warning messages during the use of Coriander. This is great for debug, but I don't think you'll need it. More interesting is the Performances tab which shows the bandwidth usage (per bus) and a report on currently running services. The latter list is cool to spot framedropping (provided that you start ISO after starting all the services or that you start the receive service last).
More information, questions, problems,...
|© 2019 Damien Douxchamps. All rights reserved.|