Libdc1394 Library Support for IEEE 1394 Cameras HOWTO
Contents
1. 4 2 Types of functions We have categorized the functions provided by the library into 6 types The categorization is purely done on our own for the ease of discussion Each of these functions has been declared in dc1394_control h We suggest you to keep a copy of the file on hand while going through the subsequent section 1 Get Query Functions 2 Set Functions 3 Print Functions 4 Setup Functions 5 Format7 Functions 6 Release Functions 4 2 1 Get Query Functions These functions are used to get the value of various features of the camera the information about the ISO channel trigger mode frame rate format and mode The functions contain get or query in their names For example 4 Concepts and Basic Programs 7 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO int dc1394_get_gamma rawl394handle_t handle node_t node unsigned int gamma gets the value of the gamma attribute for the camera Most of the get functions take a minimum of three parameters 1 Both the raw1394handle_t and node_t nodes these two together identify the camera 2 A pointer to obtain the value forexample int gamma If we try to trace the flow of the function call we can understand what actually happens Figure 1 Flow of get function call Get function call for eg dc1394_get_gamma No c gt Incase the get query function is about obtaining the value of a feature provided by the camera By feature we mean the charac2. Close camera Y y dc1394_dma_done_with_buffer camera dc1394_dma_release_camera handle amp camera dc1394_destroy_handle handle drama Menealo Camera released RETE aw p Step END return 0 Just like the previous example Section 4 4 the program includes the necessary header files 1 ibraw1394 raw1394 h and 1ibdc1394 dc1394_control h and then declare the three variables of the following data type edc1394_cameracapture e raw1394handle_t enodeid_t After this the following steps are followed which are very similar to the previous example Section 4 4 1 Open ohci and assign handle to it using the function dc1394_create_handle 0 2 Get the camera nodes using the function dc1394_get_camera_nodes 3 Find out various parameters need to be passed during the camera setup This is done by querying the camera using the following functions dc1394_get_iso_channel_and_speed To get the channel and speed information dc1394_get_video_format To get the camera format dc1394_get_video_framerate To get the framerate information dc1394_get_video_mode To get the camera mode Also we are required to set the dma buffersto 8 and number of drop framesto l Once the values of the parameter have been obtained framerate format mode channel speed etc they are passed in dc1394_dma_setup_capture which then sets up the camera and enables it for 4 Concepts and Basic Programs 22 Libdc1394 Lib
3. Install libdc1394 1 1 0 su root if you haven t already tar xvzf libdc1394 1 1 0 tar gz cd libdc1394 1 1 0 configure ed libdc1394 make make install ZAMAw Install the modules 1 modprobe ohcil394 2 modprobe video 1394 3 modprobe ieee1394 4 modprobe raw1394 3 Installation 3 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO 5 Ismod to view that all the modules ieee 1394 raw1394 ohcil394 and video1394 are now installed Note on dependencies The modules have some dependencies e ohcil394 to video1394 e ieee 1394 to video1394 ohci1394 and raw1394 So if you are installing modules with insmod video1394 and raw1394 have to be installed first followed by ohci1394 and ieee1394 Create proper 1394 devices ed dev mknod raw1394 c 1710 chmod 666 dev raw1394 mkdir video1394 cd video1394 mknod 0 c 171 16 mknod 1 c 171 17 chmod 666 dev video1394 ADUANA ps S Note on automating module start up Every time the system is restarted the nodes are destroyed and the modules are removed automatically So we wrote a script to automate this installation task at start up to undo all the damage done during rebooting Set user paths 1 su user 2 Check for the LD_LIBRARY_PATH It should contain usr local 1lib This is necessary to run the applications with the help of the shared 1ibdc1394_cotrol so 13 object file g Note on setting path You can al
4. capture function again Make sure not to call dma_unlistenuntil you are ready to stop iso transmission e Channel 0 is already being used This means you have set two camera nodes to the same Channel Fix your dma_setup_capture This could also mean that you have tried to call the setup function more than once without releasing the camera between the calls This error is more likely to occur when you are working with more than one camera e Buffer 0 is already being used This means that you have not freed the DMA buffer before trying to write to it again Make sure to alternate dma_done_with_buffer calls with dma_capture_calls A 4 Dedications 39
5. n 4 Concepts and Basic Programs speed framer 20 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Check line d of s to ensure that the options set are sx dc1394 destroy_handle handle dc1394_free_camera_nodes camera_nodes iaeicwuan p elsel printf dma1394 Capture has been setup n dc1394_free_camera_nodes camera_nodes Set Trigger Mod Generally not required thus I will comment it out if dc1394_set_trigger_mode handle camera node TRIGGER_MODE_0 DC1394 SUCCESS fprintf stderr dmal394 Unable to set the camera trigger mode Refer to line c dc1394_release_camera handle amp camera dc1394 _ destroy_handle handle elsel printf dma1394 Successfully set trigger mode n ys Step 4 Start sending data ES Bea if dc1394 start_iso_transmission handle camera node DC1394 SUCCESS fprintf stderr dmal394 Unable to start the data transmission n dc1394_dma_done_with_buffer amp camera dc1394_dma_release_camera handle amp camera dc1394_destroy_handle handle situa iLp elsel printf dmal394 Success Data Transmission started n Sas Be Cajas Soimercioalines y y Aclara y y ISE es wep if dc1394_dma_single_capture amp camera DC1394_ SUCCESS fprintf stderr dmal394 DAIM can t capture a single frame n dc1394_dma_done_with_buffer amp camera important step dc139
6. 0 dai ai it ii a tdci dee 13 4 3 Coriander A GUI for the libdc1394 libraty oooconncccnnnccnonccononanonnccnnononnnccnnnononnncnnnnccnnn conc cccnnnnnns 14 4 4 Example How to grab image from the TEEE1394 caMera ocoonoccnnoccnoncccnnccnonnnonnncnnnnccnnn conan ccnnnnnnns 14 4 5 Example How to grab image from the IEEE1394 camera using DMA cooooconnocccnonininnnccnnncconcninnnoss 19 4 6 How to get color images Bayer Pattern CONCEP S ccooccccococnonnnonoccnonncconononnnnonona cn nacnnn nc cnnnccnnnccnnnnos 24 4 6 1 Nearest Neighbor Algorithm ss iiie eeccececceesseceesaeeeaceceeeeceeeeesaeceeaeceeaeeceacecaeeeeaaeceaaeceeneeeaes 26 4 6 2 Example program to understand how the colored image is grabbed using IREE1394 CAMA sever essa haere ea A EI es a ea et ieee ee 27 4 7 Common Problems Faced While Working With TEEE1394 CameraS ocooncccnocnnnonicionnccnnnccancncnnnoss 32 By AR Of CL NO 34 AA LE E b O 35 NEE E BAT TN 36 V PAI ETA NO 37 Ja ERIA L a LEL CO ESS AAEE E EE E EEE EEE E EEE E E EE EA 38 Asd Dedicati hS ON 39 1 Introduction We felt a HOWTO on this topic was required since very little documentation is available for the libdc1394 library Moreover the IEEE1394 cameras are gaining popularity which will lead to many people using this library to develop applications for cameras on Linux This HOWTO is an outcome of our experience working with the Point Grey Dragonfly IEEE1394 camera on Linux We have given the overview of the
7. BayerNearestNeighbor After the buffer has been filled with the RGB values we write it in the file image rgb In order to view this image using gimp we need to append a bitmap header The method we employed was as follows 1 Save the RGB image buffer in a file say image rgb 2 Make a bitmap header and save it in a separate file bmpheader Refer to http www fortunecity com skyscraper windows 364 bmpffrmt html for header details 3 cat bmpheader image rgb gt bmpfile 4 Open bmpf ile using gimp In order to run the program use the following steps g c conversions cpp g o grabcolor conversions o grabcolor cpp lraw1394 LAO AO rol 4 Concepts and Basic Programs 31 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Note on available algorithms There are many algorithms that are available in conversions cpp so depending upon the requirements you can call the necessary functions The Coriander application is useful in finding out how the RGB image will look after undergoing different conversion algorithms For example it provides the choice between Nearest Neighbor Edge Sense and Down Sample conversion algorithms The difference can be observed on a mouse click 4 7 Common Problems Faced While Working With IEEE1394 Cameras We now look at some of the common problems faced while working with the camera however we have only listed those problems which we faced These problems are likely to be fa
8. and Basic Programs 25 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO To get a clear picture of what s happening we have provided the following diagram Figure 9 Bayer to Bitmap conversion IEEE1394 RGB gt Camera E A Algorithm Bayer Pattem Image BGGR or RGGB or GREG or GBRG Bayer Pattem Filter laa Without Bayer Pattern Filter i e if we remove the filter from the camera A vuu u PGM header RGB Image Gray scale that cannot be converted to colored image Bitmap Header that s why we need a filter PGM Image Hence we need to consider the other path i e when the filter is present without colors Colored Bitmap Image Let s understand how the RAW to RGB conversion algorithms work We will look into the Nearest Neighbor algorithm in detail Other Algorithms are thoroughly explained at the following web link http www ise stanford edu tingchen main htm Most of these algorithms make use of some kind of interpolations 4 6 1 Nearest Neighbor Algorithm In this interpolation method each interpolated output pixel is assigned the value of the nearest pixel in the input image The nearest neighbor can be any one of the upper lower left or right pixels An example will make the logic clear We try to find the G values for the R B tiles for a 3x3 block shown as shaded region The blank squares either bear R value or B value We have not shown them just t
9. and so forth 4 Close Coriander 5 Execute your program Bingo It works S Note on first step above The first step is critical since we experienced an error message from Coriander about not finding the camera if we did not disconnect and reconnect the camera before running Coriander 4 Concepts and Basic Programs 33 5 References 1 http kauri auck irl cri nz johanns libdc1394 libdc1394 FAQ html libdc1394 FAQ by Johann Schoonees http www ptgrey com http www ise stanford edu tingchen http damien douxchamps net ieee1394 coriander manual php Point Grey Dragonfly Camera Technical Reference Manual Version 2 1 2 1 3 Raw Capture A Second Chance to Get it Right by Charlotte K Lowrie 2005 09 01 http www linuxfocus org http www fortunecity com skyscraper windows 364 bmpffrmt html OCAIADKHAWH 5 References 34 A Appendix A A Appendix A A 1 License This document Libdc 1394 Library support for IEEE 1394 Cameras HOWTO is copyrighted 2005 by Rohit Agarwal amp Vikram B Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation with no Invariant Sections with no Front Cover Texts and with no Back Cover Texts A copy of the license is available at http www gnu org copyleft fdl html A 1 License 36 A 2 Disclaimer Althoug
10. colors being read in 0 0 0 1 1 0 1 1 order So for the above Bayer Pattern if we take the 2x2 matrix as Figure 6 BGGR Pattern 4 Concepts and Basic Programs 24 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO The pattern is therefore known as BGGR The other possible patterns are Figure 7 Other Patterns eo e e Er RGGB GRBG GBRG The image we obtained in the previous example was a Bayer Pattern image also known as a RAW image This was stored in camera capture_buffer In order to view what we have captured we convert this RAW image to PGM by adding a header look at the explanation in Section 4 4 In order to get a colored image the Bayer Pattern image is converted to a RGB image A RGB image is an enhanced version of the Bayer Pattern image we try to find the value of the two missing colors at each pixel remember that each pixel of the sensor is covered by Bayer Pattern filter so we get a single color at any pixel by default This is done by using different algorithms like Nearest Neighbor Edge Sense and so on Figure 8 RAW to RGB Es 60 Bo mjs gt RAW RGB where the shaded values are to be calculated by the algorithm Subscript denotes the tile on the Bayer Pattern to which the value of R G and B belongs Note that the image size will become 3 times the Bayer Pattern In order to view the RGB image we convert it to a Bit Map or BMP image by adding a bitmap header 4 Concepts
11. in Section 4 4 e Problem 5 IDEO1394_TIOC_LISTEN_CHANNEL ioctl failed error message being displayed Solution contributed by Ian and Tim There are various reasons for this error message Type dmesg in the command prompt to gain a better understanding of the problem Here is a list of problem we ran into 1 e Problem 6 Used CTRL C to terminate the image grabbing program but the next time the program is run it just hangs Solution The error usually occurs because the camera functions like a pipe and experiences a broken pipe situation if terminated without flushing the memory channels The trick is to disconnect 4 Concepts and Basic Programs 32 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO the camera and connect it again One can also try debugging the problem by reinstalling the ohcil 394 video1394 raw1394 video1394 modules which works occasionally e Problem 7 Every parameter is okay and the installation is also fine but even then when the program is executed the camera is still not detected Solution This is a strange problem which we also face frequently The solution is based on trial and error but it always works 1 Disconnect the camera first and then reconnect it 2 Now run Coriander that s why we suggest that you install Coriander before you start working with the camera 3 Make all the necessary adjustments for example select the mode of the camera the frame size
12. run the code make sure that you have the following files econversions h econversions cpp egrabcolor cpp also from the grabdma folder We have modified the code according to our requirements and removed some of the lines Since most of the code is same as the previously discussed code we have explained only the portions that are different These portions have been emphasized include lt stdio h gt include lt libraw1394 raw1394 h gt include lt libdc1394 dc1394 control h gt include lt stdlib h gt include lt onversions h gt define IMAGE Image rgb ame masia LINE cue Claas eueepy 1 4 Concepts and Basic Programs 27 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO FILE imagefile dc1394 cameracapture camera int numNodes int numCameras rawl394handle_t handle nodeid_t camera_nodes int channel speed mode bytes_per_packet Open ohci and asign handle to it handle dc1394_create_handle 0 if handle NULL fprintf stderr Unable to aquire a raw1394 handle n n Please check n n if the kernel modules ieeel394 raw1394 and ohcil394 are loaded n if you have read write access to dev raw1394 n n exit 1 get the camera nodes and describe them as we find them numNodes raw1394_get_nodecount handle Camera_nodes dc1394_ get_camera_nodes handle numCameras 1 tiie stdout if numCameras lt 1 Hao relen
13. signal Depending on the camera either 12 or 14 bits of data are recorded At 12 bits the camera can record 4 096 levels of brightness At 14 bits the camera can record 16 384 levels of brightness This is referred to as bit depth The higher the bit depth the finer is the detail the smoother the transition between tones and the higher the dynamic range the ability of the camera to hold detail in both highlighted and shadowed areas But at capture digital images are grayscale not color To record color information each pixel on the sensor is covered with a red green or blue filter with the colors alternating A common arrangement of color filters is the Bayer Pattern array that alternates colors but that also uses twice as many green filters as red and blue Twice as many green filters are used because our eyes are more sensitive to green This pattern or sequence of filters can vary but the widely adopted Bayer Pattern which was invented at Kodak is a repeating 2x2 arrangement Each pixel has been made sensitive only to one color one spectral band A Typical Bayer Pattern will look like this Figure 5 Bayer Pattern The tile or square pixel labeled B means this particular tile is sensitive only to Blue light and so on The Bayer Patterns may be classified into 4 types depending on how we have arranged the colors The naming of the Bayer Pattern is done by taking a 2x2 matrix from the top most corner of the pattern and the
14. the IEEE1394 camera 1 There can be more than one camera connected to the host card at any time hence one need to uniquely identify the camera node 2 The camera has some control registers to set camera features 3 According to IEEE specifications the camera can grab images in different formats The image formats are defined by two parameters format and mode Five modes are defined a Format_0 contains low resolution mode up to 640x480 b Format_1 contains medium resolution modes 800x600 and 1024x768 c Format_2 contains mega pixel modes 1280x960 and 1600x1200 d Format_7 is the scalable image format With this you can change the image size color coding and other parameters It may be possible that a camera does not support some modes so we need to be careful during the setup You use setup to set various parameters like data speed image mode framerate that are necessary to make the camera ready to grab the image We will shortly discuss setup functions 4 In order to set or get the values of the parameters features of the camera the library functions will modify or read the register values 5 The camera can work with or without DMA We are greatful to lan Peikon and Tim Hanson for contributing a section on IEEE1394 camera using DMA support 4 Concepts and Basic Programs 6 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO With the above background we begin our discussion about the various functions data structures and oth
15. 4_dma_release_camera handle amp camera dc1394_destroy_handle handle ieeyeeueigy Le elsel pramme Mamas gls ERWAT SUCCESS Cajicwicecl e Saline lle ice ya Step 6 Stop sending data Je y if dc1394_dma_unlisten handle camera DC1394_ SUCCESS orcas siecle Cane valirsten iso CloieuaiaSJl yal elsel printf dma1394 DMA unlistened An if dc1394_stop_iso_transmission handle camera node DC1394_SUCCESS morsa Secar Y Cante Stoa Juas canorall Nany elsel printf dma1394 Data transmission terminated An 4 Concepts and Basic Programs 21 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Step 7 Save our image he E imagefile fopen IMAGE_FILE_NAME w if imagefile NULL perror dma1394 Can t create IMAGE FILE_NAME dc1394_ dma_done_with_buffer amp camera dc1394_dma_release_camera handle amp camera dc1394_destroy_handle handle Sicilia Le elsel cout lt lt dmal394 Saved image in lt lt IMAGE_FILE_NAME lt lt n Add pgm file header fprintf imagefile P5 n u u 255 n camera frame_width camera frame_height write to file fwrite const char camera capture_buffer 1 camera frame_height camera frame_width in fclose imagefile printf dmal394 wrote IMAGE_FILE_NAME n Step 8
16. 5 4 Concepts and Basic Programs At present the documents that are available for understanding libdc1394 are very few Among the available documents are a FAQ which only talks about the general concept of the camera and a few forums where people have posted their queries We had to read the libdc 1394 source code to understand how to grab a frame from the camera The extreme need for a complete explanation on this topic encouraged us to write this HOWTO On the basis of what we understood by exploring the source code of the camera we are presenting our insights on the library We encourage you to keep referring following files while reading through the next section 1 dc1394_control h 2 dc1394_control c E 3 dc1394_capture 4 dc1394_format 7 The dc1394_control h file is the most important as it contains the declaration of various functions and data structures It should be read to understand the features supported by IEEE1394 cameras and the functions which access and control various features of camera The dc1394 library works closely with raw1394 since all the functions make use of functions of raw1394 raw1394_read and raw1394_write in order to retrieve or modify the values of various parameters of the camera This is one of the reasons why raw1394 must be installed before installing libdc1394 To understand how the functions provided by the library work we need to understand few technical aspects of
17. 94_getcamera_nodes handle amp numCameras 1 If the number of cameras returned is numCameras lt 1 this means no camera has been detected 1 in the function signifies that a printed description of the camera node found will be shown on the console Check the condition of camera_nodes 0 numNodes 1 It must be false The explanation o for this is outside the scope of this document Call the setup function and pass the various parameters For example let us examine the setup function of the above example dc1394_setup_capture handle and camera_nodes 0 uniquely identifies the camera handle camera_nodes 0 De Charme lt format of the Image FORMAT_VGA_NONCOMPRESSED MODE_640x480_MONO mode of the image SPEED_400 data speed FRAMERATE _7_5 Frame rate amp camera dc1394_cameracapture type pointer DC1394_SUCCESS Our suggestion is that the various parameters should be first queried from the camera and then passed This is helpful in a successful setup since often the user does not know actual values of the various parameters that have to be passed in the setup function call and ends up passing the wrong values In such situations the setup is not done correctly and the camera doesn t get initialized We are listing the appropriate get functions that should be called first in order to obtain the correct values of the setup parameters 4 Co
18. Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Rohit Agarwal lt rohdimp 24 rediffmail com gt Vikram B lt vickys box rediffmail com gt 2006 01 23 Revision History Revision 1 2 2007 04 14 Revised by RA Addition of DMA related section contributed by lan Peikon lt idp2 duke edu gt and Tim Hanson lt tim hardcarve com gt Revision 1 0 2006 01 23 Revised by TMM Initial release reviewed by TLDP Revision 0 4 2005 12 18 Revised by TMM Correction of markup Revision 0 3 2005 11 27 Revised by TMM Conversion to DocBook XML Revision 0 2 2005 10 15 Revised by VB Minor fixes Revision 0 1 2005 10 10 Revised by RA amp VB Initial draft This document discusses how to set up the libdc1394 library on Linux for support of IEEE 1394 FireWire cameras Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Table of Contents DTD KTT BTO I E EEE PET E S AE ENEE ES AET EEE E E E A tech es tea ssesnveabestes 1 A OO 2 IO A NO 3 4 Concepts and Basic Programs sscissescssensssscessssseseosssvecsessncssenass enssescossaessensssensessesessensesecesssntsoseasssenssseccstesesse 6 4 1 Important Data Structures avisan liinda eE ENE os ORI ARA iaa it 7 4 2 Types OF UNC iio T a 7 421 Get Query FUNCH ONS mi ds 7 4D 2S Ol O RN 9 ADS PIO A BLUTES I REEERE chose IER EEE E ETENEE AEE AE TE 10 424 Setup FUNC ONS esan iea ei aea e oT ante asad E EEE O oraka ad 10 4 5 Forma UICN a a A Aiea aa a aa ries 12 42 6 Release FUNCUONS
19. _height camera frame_width imagefile fclose imagefile 12 printf wrote IMAGE_FILE_NAME n e Close camera dc1394_release_camera handle camera dc1394_destroy_handle handle return 0 13 Include the header files which means include libraw1394 raw1394 h 4 Concepts and Basic Programs 16 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO 1ibdc1394 dc1394_control h These are necessary in order to access functions of the library 12 Declare three variables of the following data types dc1394_cameracapture rawl394handle_t e nodeid_t The raw1394handle_t and nodeid_t are required to uniquely identify the camera Moreover raw1394handle_t is used to hold the handle that is created for the OHCI compliant host card Open ohci and assign a handle to it This is done by handle dc1394_create_handle 0 Where handle is of the raw1394handle_ttype gt type The parameter 0 refers to the position of the camera on host card there may be more than one slot on the host card 0 means that the camera is on the first slot 0 If the wrong number is passed the handle will not be created Get camera nodes There can be more than one camera node since IEEE1394 supports multiple devices on a single port But for our discussion we will assume that only a single camera is present Here is how to get nodes int numNodes raw1394_get_nodecount raw1394handle_t handle Camera_nodes dc13
20. alues raw1394 readQ The Format set functions also follow the same logic with the obvious difference that the reading functions are replaced by writing functions for example Set CameraFormat 7Register and raw1394_write 4 2 6 Release Functions These are the final set of functions identified by us The basic job of these functions is to release the memory allocated to the capture buffer by the setup routine This is essential to save the system from memory leaks These functions are defined in dc1394_capture c dc1394_release_camera This function in turn calls free camera gt capture_buffer which frees the memory Similarly the release function is available for DMA setup 4 Concepts and Basic Programs 13 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO 4 3 Coriander A GUI for the libdc1394 library Coriander helps in easy handling of the IEEE1394 cameras It uses the above discussed functions and libraries and provides a GUI for them The main advantage of Coriander is that it saves time that is normally wasted in camera setup Also Coriander shows only those features and attributes that are present on the camera and hence you can judge how useful the camera will be for your application development The most important feature of Coriander is its ability to display the captured image at run time Coriander also allows the user to convert a BGGR image to RGB We will discuss the meaning of these types of i
21. andle camera node DC1394_ SUCCESS fprintf stderr unable to start camera iso transmissionin dc1394_release_camera handle camera dc1394_destroy_handle handle Sesto We ajuda as mesma Y n n if dc1394_single_capture handle camera DC1394_SUCC Horiaci Sires WUhoelolls jee cajebids e camela dc1394_release_camera handle camera dc1394_destroy_handle handle exit 1 query the camera to determine the Bayer pattern quadlet_t qValue GetCameraControlRegister handle Camera_nodes 0 0x1040 Bayer Tile Mapping register qgValue bayer_pattern_t pattern BAYER PATTERN_BGGR switch qValue case 0x42474752 BGGR pattern BAYER PATTERN_BGGR break case 0x47524247 GRBG pattern BAYER PATTERN_GRBG break case 0x52474742 RGGB pattern BAYER_PATTERN_RGGB break case 0x47425247 GBRG pattern BAYER_PATTERN_GBRG break case 0x59595959 YYYY BW fprintf stderr Camera is black and white n 4 Concepts and Basic Programs 29 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO cleanup Sie sia ly default fprintf stderr Camera BAYER_TILE MAPPING register has an unexpected value In Mesa even p return 1 int bufferSize camera frame_width camera frame_height assign a buffer of size thr time the original image unsigned char rgbBuffer new unsigned char 3 b
22. ayer Pattern to RGB requires to know about the type of pattern the camera filter has got so that it can carry out some initialization refer to conversions cpp for details The fourth parameter in the function call BayerNearestNeighbor src rgbButter camera frame_width camera frame_height pattern refers to this value BayerNearestNeighbor is the function call for the interpolation algorithm we discussed in the last section This is implemented in conversions cpp Having understood this we move on to the switch cases The value that is obtained for the Bayer Pattern qvalue is in the hex form which needs to be decoded for setting the value of the variable pattern The case statements indicate the various hex values relating to the Bayer Pattern that can be returned by the various cameras The intimidating values are actually quite easy to decode Here s the trick The hex code for various colors is as follows e42h gt B e47h gt G e52h gt R Now if the qvalue contains 0x42474752 it means B 42h G 47h G 47h R 52h or BGGR We can therefore decode all the case statements similarly Finally we need to declare another image buffer that will contain the RGB image Remember that the size of the RGB is 3 times the size of the Bayer Pattern image rgbbuf fer is therefore assigned 3 times the buffer size camera capture_buffer This buffer rgbbuf fer will be passed as the destination buffer the second parameter in
23. c1394 Library Support for IEEE 1394 Cameras HOWTO Get function call for eg dc1394_set_gamma No gt Hn case the set function is about setting the value of a feature provided by the camera By feature we mean the characteristics of the camera listed in feature enumeration in dc1l394 control h SetFeatureValue SetCameraControlRegister dci394 set_camera_ info yes raw1394_write 4 2 3 Print Functions There are three print functions available 1 dc1394_print_camera_info This function is used to print the values stored in the dc1394camera_info structure The print function is usually called after dc1394_get_camera_info to ensure that the dc1394camera_info structure is not NULL 2 dc1394_print_feature This function is used to print the value of any feature It takes as an input the pointer to dc1394_feature_info structure 3 dc1394_print_feature_set This function is used to print the values of all features present in the camera It takes as an input the pointer to dc1394_feature_set structure The function call basically calls dc1394_print_feature repeatedly in a for loop 4 2 4 Setup Functions As the name suggests these functions are used to prepare the camera to start grabbing the images In order to setup the camera some parameters must be passed to the function The number and the type of parameters are specific to the setup function but essentially three parameter
24. c1394 destroy_handle handle iaeieuuein L e else cout lt lt dma1l394 lt lt numCameras lt lt cameras found An printf dmal394 Working with the first camera on the bus n if camera_nodes 0 numNodes 1 fprintf stderr An dmal1394 Sorry your camera is the highest numbered node r dc1394_destroy_handle handle dc1394_free_camera_nodes camera_nodes cetunn dls Step 3 Setup Capture do a Using camera functions to get the params by querying them cout lt lt INFO FOR DEBUG n num_dma_buffers lt lt camera num_dma_buffers lt lt n dc1394_get_iso_channel_and_speed handle camera_nodes 0 amp channel amp speed get channe dc1394_get_video_format handle camera_nodes 0 amp format get format dc1394_get_video_framerate handle camera_nodes 0 amp framerate get framerate dc1394_get_video_mode handle camera_nodes 0 amp mode get mode cout lt lt dc1394 Got parameters from the camera n ai Miners EE diecmnasles Y aw Speed lt lt speed lt lt An Tinos lt lt forme lt lt NinW Mraz lt lt irivsnneicsice lt lt ya MOSES O ASA niy camera num_dma_buffers 8 set the dma buffers camera drop_frames 1 set the number of drop frames camera dma_device_file NULL if dc1394_dma_setup_capture handle camera_nodes 0 channel format mode fprintf stderr dmal394 Unable to setup camera
25. ced by anyone who uses the library and the camera Some of the problems were solved with a proper reasoning but some were just hit and miss attempts The problems and their solutions are listed below e Problem 1 After the installation of the library and the modules the camera did not respond Solution We disconnected the camera and connected it again May be this has to be repeated multiple times We could not figure out an appropriate reason for this but it works e Problem 2 Program is not compiling Solution If one forgets to link the executable with raw1394 and dc1394_control the program won t compile The correct way is GEE O 30 ye mllicchiyl SSA lelsil 394 comio y7 ror E ilies Garr Re x Gj lravloga lelelAaQa_coimtwol for Gaa alles e Problem 3 Compilation failed giving the error Libdc1394_control so 13 cannot open the shared object file Solution Check for the environment variable LD_LIBRARY_PATH This should contain the path of the shares library On our system the path was usr local 1ib The path must be set accordingly e Problem 4 Program hangs when executed Solution This primarily happens if the values of parameters that are passed to the setup function are not supported by the camera For e g setting the mode mode_640x480_MONO16 when it is not supported Our suggestion is that one should always query for the values and then pass them to the function as explained in the example code located
26. create_handle 0 O if handle NULL fprintf stderr Unable to aquire a raw1394 handle n n Y aia dE 4 Concepts and Basic Programs 14 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO get the camera nodes and describe them as we find them numNodes raw1394_get_nodecount handle camera_nodes dc1394_ get_camera_nodes handle numCameras 1 flush stdout if numCameras lt 1 morbo sectaria Mao cameras roune 2 Na dc1394_destroy_handle handle exit 1 printf working with the first camera on the bus n if camera_nodes 0 numNodes 1 morata siecleria VaN Sorry your camera is the highest numbered node n dc1394_destroy_handle handle dc1394_free_camera_nodes camera_nodes SAR setup capture if dc1394_setup_capture handle camera_nodes 0 6 0 channel FORMAT_VGA_NONCOMPRESSED MODE_640x480_MONO SPEED_400 FRAMERATE_7_5 Camera DC1394_SUCCI Se n n fprintf stderr unable to setup camera n check line d of s to make sure n that the video mode framerate and format are n supported by your camera n EN hs na OA dc1394_release_camera handle camera dc1394_destroy_handle handle dc1394_free_camera_nodes camera_nodes SA dc1394_free_camera_nodes camera_nodes set trigger mode if dc1394_set_trigge
27. e would have to change only the setup_capture function Let us look at the setup function dc1394_setup_format7_capture handle and camera_nodes 0 uniquely identifies the camera handle camera_nodes 0 chan IE a morte y mode y bytes_per_packet left farea Or lmesrzest siesta colla lt rigat Sauasa CHE darse Start io quel 2 arsa OIE alinieeisesic mica lt y height area of interest height camera dc1394 cameracapture type pointer DC1394_ SUCCESS where the values of the parameters for channel speed bytes_per_packet speed mode are found using the following functions 1 dc1394_get_iso_channel_and_speed handle camera_nodes 0 amp channel amp speed to get the channel and the data speed 2 dc1394_get_video_mode handle camera_nodes 0 amp mode to get the mode 3 dc1394_query_format7_byte_per_packet handle camera_nodes 0 mode amp bytes_per_packet to get the bytes per packet which depends on the mode 4 The value of left top can be set to QUERY_FROM_CAMERA or can be specified directly by the user 5 The value of the width and height depends on the size of frame the user wants for example if one wants 960x720 then pass 960 as width and 720 as height 4 5 Example How to grab image from the IEEE1394 camera using DMA This section has been contributed by Ian Peikon lt idp2 duke edu gt and Tim Hanson lt tim hardcarve com gt We wi
28. er miscellaneous features available in the dc1394 control h file We would like to mention one important aspect of the dc1394_control h file which is that it lists out the values that can be set for the data speeds frame rates camera modes and image formats All the values are in the form of enumerations to help you write readable code For example enumeration for speed indicates that the data speed can be set only as 100 200 400 800 1600 or 3200 The dc1394_control h also lists the features brightness hue sharpness saturation etc supported for your camera 4 1 Important Data Structures The library provides some structures which are useful in storing camera and image related information They have been declared in the dc1394_ control h file tructure Use Helps in accessing the information about the camera model vendor ccr_offset used dc1394_camerainfo to access the registers Contains various parameters that are to be manipulated while the camera setup It dc1394_cameracapture also declares a buffer of int type that will be used to store the grabbed frame UEIN Contains the information about the ISO channel id iso channel speed memory dc1394_misc_info channel number Contains the information about a particular feature brightness hue gamma white 0E1294 panie Tio balance etc for example the availability and values for it We will be largely concerned with the dc1394_cameracapture structure
29. h we have tried to do our best to bring out this HOWTO in a good form we are not responsible for any damage due to the actions taken based upon the information contained in this document It is impossible to test things under all the configurations so probably some of the hints given in this document may be incorrect and may not work on your system In case you find anything wrong let us know it first We will rewrite the document as soon as possible This document is provided as is We put great effort into writing it as accurately as we could but you are using the information contained herein at your own risk In no event shall we be liable for any damages resulting from the use of this work A 2 Disclaimer 37 A 3 About Authors Rohit Agarwal and Vikram B are pursuing their Masters Degrees in IT from the International Institute of Information Technology Bangalore India They can be contacted at e rohdimp_24 rediffmail com lt Rohit gt e vickys_box rediffmail com lt Vikram gt A 3 About Authors 38 A 4 Dedications We are grateful to all our friends for their support We would specially like to thank Chinmay Narayan our batch mate for his valuable advices We would like to dedicate this document to our Professor Mr S Nagrajan for he is the one who motivated us to contribute to the open source community Notes Ol e Channel 0 is not being used This means you are listening on the iso channel and then calling a
30. image to be captured according to his need By default the size is 1024x768 you can set it to different dimensions say 960x720 4 Concepts and Basic Programs 12 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO All Format7 functions have format 7 in their function names and the functions have been defined in a separate file dc1394_format7 c The setup function for Format7 has a minor difference from the normal setup since it also asks for the size of the frame while you don t have to pass the format parameter as the setup function as it is meant only for a particular format for example Format7 The function call flow remains the same as discussed in the previous section The Format7 get functions are called query functions The mechanism is different from the normal get query functions they don t call Get CameraControlRegister instead they call GetCameraFormat7Register The following flowchart will make the differences evident Figure 4 Flow of the Format7 query function call Format query function call GetCameraFormat 7Register Quer yFormat CSROffset The Format7 query function will call Get CameraFormat 7Register which is supposed to read the values from the control and status registers of the camera This function in turn will call the QueryFormat and CSROffset to know the offset for the particular information that has been queried After getting the offset raw1394_read is used to actually read the v
31. library in layman s terms so anybody who has some programming experience will easily understand the contents 1 Introduction 1 2 Requirements Various libraries and modules required are e Library libdc1394 1 1 0 e Supporting Library libraw1394 1 2 0 e Supporting Modules ieee1394 raw1394 ohci1394 video1394 e Linux Kernel 2 6 10 or above 2 Requirements 3 Installation Prerequisite Make sure that the kernel is compiled with IEEE1394 built in support This is critical You can add support for the IEEE1394 devices by compiling the kernel again Don t panic Here are the steps to compile the kernel Go to the directory where your kernel source code is present Normally it is in usr src We suggest that you download a fresh copy of the kernel source code 2 6 10 from www kerneLorg Thus cd usr sre kernel 2 6 10 kerne1 2 6 10 is the name of the source code directory It can vary from system to system 1 make menuconfig 2 The menu will come up Select Device Drivers 3 The Device Drivers menu will come up Select IEEE1394 Firewire Support 4 Mark the following as lt M gt in the menu that is shown a OHCI 1394 support b OHCI 1394 Video Support c OHCI 1394 DVI O Support d RAW IEEE1394 I O Support 5 Press ESC to come out of the menu 6 Save the configuration Install libraw1394 1 2 0 su root tar xvzf libraw1394 1 2 0 tar gz cd libraw1394 1 2 0 configure make make install
32. ll now present an example of how to grab a frame by the camera using DMA calls The example is simple to understand as the logic remains the same as the previous example We will later compare the function calls used in the previous example without dma and this example with dma for better understanding include lt stdio h gt include lt libraw1394 raw1394 h gt include lt libdc1394 dc1394 control h gt include lt stdlib h gt include lt iostream gt define IMAGE _FILE_NAME Image pgm using namespace std 4 Concepts and Basic Programs 19 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO dae esta IME arer Char emo 111 4 FILE imagefile dc1394 cameracapture camera int numNodes int numCameras rawl394handle_t handle nodeid_t camera_nodes unsigned int channel speed format framerate mode See ike Ojsyei Clavel uatcl elsistiefa lt i loveiavelilie ieoy Wie es E handle dc1394_create_handle 0 if handle NULL fprintf stderr Unable to acquire a handle n n elsel cout lt lt dmal394 Handle aquired successfully lt lt handle lt lt n Step 2 Get the camera nodes and describe them as we find them fo a numNodes raw1394_get_nodecount handle camera_nodes dc1394_get_camera_nodes handle amp numCameras 1 Pilashistdout gt if numCameras lt 1 fprintf stderr No cameras found n d
33. mages in detail in later sections Some files that can be useful in understanding the functionality of Coriander are l thread_iso c 2 Camera c 3 main c The Coriander homepage contains an excellent user manual which can be useful in case of any difficulty http damien douxchamps net eee1394 coriander manual php Our use of Coriander was limited only to checking that the camera was working properly and confirming the focus was correct We will give some more usage information for Coriander in later sections 4 4 Example How to grab image from the IEEE1394 camera In this section we will demonstrate how to write a small program to grab an image from the camera We have taken the program grab_gray_image c given in the examples in the library tar file We have removed some lines to increase the readability of the code We have provided the explanation for this code below In order to provide you with a clear picture of which section of the code does what we grouped the code lines together by task below include lt stdio h gt include lt libraw1394 raw1394 h gt include lt libdc1394 dc1394_control h gt include lt stdlib h gt 11 define IMAGE_FILE_NAME Image pgm aloe mein GME eee Clague cuz 11 FILE imagefile dc1394_cameracapture camera int numNodes int numCameras raw1394handle_t handle nodeid_t camera_nodes 2 Open ohci and asign handle to it handle dc1394
34. mera_info to get the address of the base register camera gt ccr_base CONFIG_ROM_BASE info gt ccr_offset Once the base register and the offset is known raw1394_ read is called by GetCameraControlRegister to read the actual values Now the get function dc1394_get_gamma uses the value returned by the GetCameraControlRegister to modify the parameter gamma int dc1394_get_gamma raw1394handle_t handle node_t node unsigned int gamma In this way the user obtains the value of the camera parameter he queried for 4 2 2 Set Functions These functions are used to set the values of various camera features There is a corresponding set function for almost each get function You can recognize these functions by searching for set string For example dc1394_set_gamma rawl394handle_t handle nodeid_t node int gamma Like the get function this function needs raw1394handle_t and nodeid_t for camera identification The other parameter gamma is the user specified value for the gamma parameter The flow of the function call is quite helpful in understanding what is actually happening The flow is exactly same as that of the get function The only difference is this time all the intermediate functions are also set functions and instead of raw1394_read ituses raw1394_write to write the value of the camera parameter on to the registers Figure 2 Flow of set function call 4 Concepts and Basic Programs 9 Libd
35. method We have compared the functions used in two approaches in the following table Non DMA steps DMA steps Comments 1394 create_handle dc1394_create_handle Create handle t 1394_get_camera_nodes dc1394_get_camera_nodes dc1394_setup_capture dc1394_dma_setup_capture dc1394 start_iso_transmission dc1394 start_iso_transmission 1394 _dma_single_capture 1394_singl ds 1394 dma done with buffer dc1394_stop_iso_transmission 4 Concepts and Basic Programs 23 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO dc1394_dma_unlisten Stop sending dc1394_stop_iso_transmission the data from camera to the bus dc1394_dma_done_with_buffer ac1394_release_camera gt dc1394_destroy_handle Selo tte Te Leese cane camera ES Y dc1394_destroy_handle 4 6 How to get color images Bayer Pattern Concepts The image grabbed by the sample code in the previous section is not colored we have intentionally used the words not colored since the image is not gray scale either It is actually a Bayer Pattern We will give an overview of Bayer Patterns and how they are used to get a colored image in this section Digital cameras use a solid state device called an image sensor These fingernail sized silicon chips contain millions of photosensitive diodes called photosites When you take a picture with a digital camera the intensity of light hitting each photo site on the sensor is recorded as a
36. mpile and execute the programs cd libdc1394 1 1 0 examples make You can get programs exclusively written for the Point Grey cameras at http www pterey com support kb data grabdma tgz Fortunately we have an open source graphical application developed for the IEEE1394 cameras known as Coriander that provides a nice Graphical User Interface for libdc1394 to help the user work with the camera more efficiently Later we will discuss how Coriander helped us in debugging Next we briefly explain how to install Coriander Installation of Coriander 1 Make sure that you have libdc1394 and the Gnome libraries Coriander uses gnome h installed on your Linux machine For more details regarding the requirements look into the user manual provided by Coriander http damien douxchamps net ieee1394 coriander manual php 2 Download the following tar file from sourceforge net coriander 1 0 1 tar gz then proceed as shown below su root tar xvzf coriander 1 0 1 tar gz ed coriander 1 0 1 configure cd sre make g make install 3 Run Coriander as follows ed corlanden la0ml comlanden ls Oe l sire coriander Fortunately the installation of the libdc1394 and related modules is simple and does not pose any major problems Some minor problems you may face are due to mistakes such as not installing it as root or not changing the permissions of the newly created IEEE1394 devices 40 Aaa Tp 3 Installation
37. n handle camera node Capture one frame by calling the function dc1394_single_capture handle amp camera Where camera is a pointer to the structure dc1394_cameracapture This function will grab the image and store it in the buffer capture_buffer provided by the structure In order to capture more than one frame use a for loop and place the function inside it for i 0 i lt 100 i to capture 100 images dc1394_single_capture handle camera After the image has been grabbed stop the data transmission by calling the following function dc1394_stop_iso_transmission handle camera node Add a PGM file header to the captured buffer to see the image using gimp Use fwrite to save the captured image by writing the buffer camera capture_buffer toa file The other parameters like height and width of the image can be extracted from the same structure camera frame_width camera frame_height 4 Concepts and Basic Programs 18 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Close the camera This step is necessary to prevent a memory leak dc1394_release_camera handle camera dc1394_destroy_handle handle In order to compile the program use gec o grabImage grabImage c Idc1394_control lIraw1394 where grabImage c is your program We hope that after going through this algorithmic way explanation you can comfortably understand the example code If we used the Format7 image format w
38. ncepts and Basic Programs 17 13 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO 1 dc1394_get_iso_channel_and_speed handle camera_nodes 0 amp channel speed to get the channel and the data speed 2 dc1394_get_video_format handle camera_nodes 0 amp format to get the format 3 dc1394_get_video_framerate handle camera_nodes 0 amp framerate to get the framerate 4 dc1394_get_video_mode handle camera_nodes 0 amp mode to get the mode So the above dc1394_setup_capture function call will look like this dc1394_setup_capture handle and camera_nodes 0 uniquely identifies the camera handle camera_nodes 0 we pass the variables instead of actual values channel format mode speed framerate camera dc1394_cameracapture type pointer a Cle AEC UC EHS Setting the trigger mode This is generally not required This is just like brightness dc1394_set_trigger_mode handle camera node TRIGGER_MODE_0 sets the trigger mode to 0 Note on nodes We have passed camera node which indicates that the dc1394_cameracapture structure is being used and only the particular node for which the camera has been setup is being referred to but we can also use camera_nodes 0 Have the camera start sending the data to the user This is done by starting the ISO transmission The following function is used dc1394_start_iso_transmissio
39. o make the figure easy to understand Here we assume the left neighboring pixel value is used to fill the missing ones 4 Concepts and Basic Programs 26 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Figure 10 Nearest Neighbour The table on the left shows the G values for the Bayer Pattern image In order to find out the missing G values for the other squares that originally contains only R or B we use the following approach Find the nearest G value square and copy the G value of that square onto the R B square This has been illustrated in the above figure The square next to G7 had a value of either R or B So to get G8 a G value for square 8 we copied the G value of square 7 since it was the nearest so G8 G7 Similarly we filled the other non G value squares The same logic is applied when finding R and B values for the green squares 4 6 2 Example program to understand how the colored image is grabbed using IEEE1394 Camera Now that we have presented the basic concept of the RAW RGB and the conversion algorithm we feel that you can understand an example program that gives us a colored image We have chosen the format as Format7 because the camera we used responds to this format only We will make use of another example code which provides the implementation of the algorithms The program is conversions cpp in the grabdma folder available for download at http www ptgrey com support kb data grabdma tgz To
40. parameters like data speed format mode and channel Instead of providing the value yourself you may instruct the function to take the value from the camera This can be done by passing QUERY_FROM_CAMERA in place of the actual value for that function parameter The basic flow of control is easy to understand Figure 3 Flow of the setup function call 4 Concepts and Basic Programs 11 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Setup function Call the set the setup function that functions related to uses DMA various parameters that have been passed Call the set functions related to various parameters that have been passed Call ioctl system call to set buffers and listen to the channel As shown in Figure 3 the Setup function in turn calls various set functions to set the parameter values to the camera registers In the case of DMA setup after the set functions have been called the ioctl system call is called to allocate memory for the DMA buffers and returns a pointer capture_buffer in user space The ioctl system calls will fail if the DMA is not setup correctly The setup functions also allocate memory for the camera _capture buffer camera gt capture_buffer int malloc camera gt quadlets_per_frame 4 4 2 5 Format7 Functions These functions are used only if the camera is set for Format7 This format is preferred since this allows the user to define the size of the
41. r_mode handle camera node TRIGGER_MODE_0 SD Cll SARSUCEESS 7 fprintf stderr unable to set camera trigger mode n if 0 dc1394_release_camera handle camera dc1394_destroy_handle handle CS El tendif have the camera start sending us data 4 Concepts and Basic Programs 15 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO if dc1394 start_iso_transmission handle camera node 1 DC1394_SUCCESS 8 fprintf stderr unable to start camera iso transmissionin dc1394_release_camera handle camera dc1394 _ destroy_handle handle exit 1 capture one frame if dc1394_single_capture handle camera DC1394_SUCCESS fprintf stderr unable to capture a frame n dc1394_release_camera handle camera dc1394_destroy_handle handle EKEN Stop data transmission pa if dc1394_stop_iso_transmission handle camera node DC1394_SUCCESS printf couldn t stop the camera n O save image as Image pgm imagefile fopen IMAGE_FILE_NAME w if imagefile NULL PERRO IC ASS IIA CEE dc1394_release_camera handle camera dc1394_destroy_handle handle exac N Adding the pgm file header fprintf imagefile P5 n u S u 2551n camera frame_width camera frame_height 11 Aa Meicia Eo cing file fwrite const char camera capture_buffer 1 camera frame
42. rary Support for IEEE 1394 Cameras HOWTO capturing video For DMA you must pass the number of dma buffers and drop frames parameter 4 After the camera is set dc1394_start_iso_transmission is called This function starts data transactions from the camera to the bus 5 Now capture one frame using dc1394_dma_single_capture This function will capture a frame into the dma buffer After the frame has been grabbed release the dma buffer using dc1394_dma_done_with_buffer This is required so that the memory can be reused It is imperative that dc1394_dma_done_with_buffer always follows a dma_capture function call So in order to capture more than one frame the code will be for 1 071 lt 100 passer to cejicuiss LOO imagest dc1394_dma_single_capture amp camera dc1394_dma_done_with_buffer amp camera 6 Stop listening to the iso channel by calling dc1394_dma_unlisten Terminate the data transmission by calling dc1394_stop_iso_transmission 7 Save the image in a file and add a PGM header for viewing using gimp 8 Finally call dc1394_release_camerato release the camera If DMA is not setup correctly you will get the following error message VI U E0O1394_TOC_LISTEN_CHANNEL ioctl failed There are various reasons for this error which will be further explained in the Problems section Section 4 7 Thus we can see that the image capture using DMA is not much different from non DMA
43. s must be passed in all the setup functions raw1394handle_t nodeid_t and the pointer to the dc1394_cameracapture structure this is to provide the buffer for grabbed images and keep attributes like height and width of frame As mentioned previously raw1394handle_t and nodeid_t uniquely define the camera while the pointer to dc1394_cameracapture provides the buffer for the image frame to be grabbed It also stores information about the width and height of the frame which is useful at the time of image processing 4 Concepts and Basic Programs 10 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO Other parameters that are passed are data speed frame rate image format image mode and ISO channel number In case the camera uses DMA the number of DMA buffers and drop frames is to be provided In most applications you will want to set the number of DMA buffers relatively low i e 1 this ensures that you are viewing frames in near real time Drop frames is also important for real time as it causes the capture function to throw away the frames buffered in the DMA ring buffer except fot the last We will discuss about DMA functions in the later part of this HowTo The various setup functions are 1 dc1394_dma_setup_capture 2 dc1394_setup_capture 3 dc1394_setup_format7_capture 4 dc1394_dma_setup_format7_capture These setup functions have been defined in dc1394_capture c You have a choice while passing the values for the
44. so set the path by adding usr local libin etc ld so conf This completes the installation phase In order to make sure the installation is correct connect the camera to the IEEE1394 card assuming that the TEEE1394 card is already installed on the system and just run testlibraw testlibraw This tests for the presence of the host card camera and other related parameters Below is a typical output from testlibraw Successfully got handle current generation number 17 1 card s found nodes on bus 2 card name ohcil394 3 Installation 4 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO US iiiesic Carel Ounces 2 mocks om lous dloeal TD is Op IRM ag i doing transactions with custom tag handler trying to send read request to node 0 completed with value 0x23127bac trying to send read request to node 1 completed with value 0x60217dac using standard tag handler and synchronous calls trying to read from node 0 completed with value 0x04477dac trying to read from node 1 completed with value 0xd37380ac testing FCP monitoring on local node got rep command from node 0 of 8 bytes 01 23 45 67 89 ab cd ef got fcp response from node 0 of 8 bytes 01 23 45 67 89 ab cd ef polling for leftover messages The 1ibdc1394 1 1 0 library comes with some example programs which are very helpful in understanding how the programs are to be written There is a Makefile available in the examples folder of the tar file To co
45. t Guest lensta ENOR Camera SE MiG 3 an gt dc1394_destroy_handle handle exit 1 printf working with the first camera on the bus n if camera_nodes 0 numNodes 1 orcas erer Mal Sorry your camera is the highest numbered node n dc1394_destroy_handle handle dc1394_free_camera_nodes camera_nodes este Le obtain the values of the parameter from the camera dc1394_get_video_mode handle camera_nodes 0 unsigned int amp mode dc1394_get_iso_channel_and_speed handle camera_nodes 0 unsigned int amp channel unsigned int amp speed dc1394_query_format7_byte_per_packet handle camera_nodes 0 unsigned mode amp bytes_per_packet setup capture if dc1394_setup_format7_capture handle camera_nodes 0 Channel ee hamme lies mode speed bytes_per_packet 0 4 Concepts and Basic Programs 28 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO 0 960 O Camera DC1394 SUCCESS fprintf stderr unable to setup camera n check line d of s to make sure n that the video mode framerate and format are n supported by your camera n IAN inicia Ae dc1394_release_camera handle camera dc1394_destroy_handle handle dc1394_free_camera_nodes camera_nodes exit 1 dc1394_free_camera_nodes camera_nodes have the camera start sending us data if dc1394 start_iso_transmission h
46. teristics of the camera listed in feature enumeration in dcl394 control h GetFeatureValue GetCameraControlRegister dc1394 get_camera_info rav1394 read yes In case the get function you called is meant to retrieve the value of a camera feature the value for the parameters listed in feature enumeration that get function will call another get function GetFeatureValue which takes the enumeration value of the feature as input For example in the case of gamma value the function passes 422 as the value this value can be calculated from the enumeration given in the dc1394_control h file Ultimately the Get CameraControlRegister function whose task is to get the value from the appropriate control registers is called This functions takes the offset value octlet_t offset which is the offset from the base register as the input to its call The function prototype is declared in dc1394_internal h GetCameraControlRegister rawl394handle_t handle nodeid_t node octlet_t offset quadlet_t value 4 Concepts and Basic Programs 8 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO The above will store the final result in the value Note on data types The library makes use of typedefed data types oct let_t and quadlet_t very frequently These are defined in dc1394_internal h and stand for 8 byte and 4 byte data types The GetCameraControlRegister function will in turn call dc1394_get_ca
47. ufferSize unsigned char src unsigned char camera capture_buffer unsigned char captureBuffer unsigned char camera capture_buffer zoe ame 2 05 a lt IVERS wes dar src i captureBuffer i bytesPerPixel J PE Omar CO Color amaga BayerNearestNeighbor src rgbBuffer camera frame_width camera frame_height pattern Stop data transmission sal if dc1394_stop_iso_transmission handle camera node DC1394_SUCCESS caer Maounilciae topi eher ecame na 2 NaN save image as Image rgb without adding any pgm header printf Saving the image n imagefile fopen IMAGE w fwrite rgbBuffer 3 bufferSize imagefile fclose imagefile Es Closs camera dc1394_release_camera handle camera dc1394_destroy_handle handle return 0 As we have already discussed the use of Get CameraControlRegister you can understand that it has been used to find out the value contained at 0x1040 Libdc1394 does not provide any function to query this address so we explicitly used this call to get the value 4 Concepts and Basic Programs 30 Libdc1394 Library Support for IEEE 1394 Cameras HOWTO It is important to understand the utility of the above function call Refer to our discussion about the Bayer Pattern filters in the previous section We know that the pattern can be BGGR RGGB GRBG and GRBG The algorithm that we use for converting the B
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