multimedia lecture board

Content	Prepare Talks / mlb document creator (mdc) Start mlb Start mlb with SDR Manage und Join Sessions Setup User Manage Documents Adjust View Thumbnail Overview Export / Import Documents Edit Documents Presentation Animations Telepointer and Telebox Feedback Voting Hand-Raising Chat Application Launch Local Recording Shared Recording Client for Handheld Devices Tips & Tricks Contact
Prepare Talks	Even though it is possible to prepare documents entirely with the mlb, it might be useful to do so with other applications (e.g., MS PowerPoint). Importing such documents into the mlb can be done via postscript, PDF, and image formats (gif, jpeg, ...). For PowerPoint we recommend to save the whole presentation as png's (i.e., PowerPoint creates a png for each slide). By importing each png, a mlb document can be created. The mlb document creator (mdc) automatizes this importing process. In order to find the correct sequence of the slides, all files need to be numbered serially, starting at 1. mdc [path] [first file] [orientation] [thumbnails] {[width] [height]} path identifies the directory in which all images to be imported are stored. Use "." if mdc is located in the same directory. first file gives the name of the first file (e.g., "img001.png"). mdc analyzes this file name to derivate the names of the following files. orientation defines the orientation of the mlb pages, whereby "0" is portrait, and "1" is landscape. thumbnails defines whether mdc shall automatically create a thumbnail overview of the document: Choose "1" for yes and "0" for no. width/height (optional) defines the width and height in pixels of the pages of the mlb document. All images are scaled automatically to fit those page dimensions. The pages' default size is DIN A4 corresponding to 594842 pixels for portrait. mdc acknowledges each imported file, missing files denote an error. It is advisable to create mlb documents well in advance of the actual presentation and test them for errors. For Linux, there is a similar tool, ps2mlb, that converts a postscript file into an mlb document. In our experience, ps2mlb achieves a very high quality. Here is how to use it ps2mlb [psfile] [pages] [rotate{degrees}] [thumbnails {0,1}] psfile* is the name of the postscript file. pages denotes the number of pages in the postscrpt file. rotate defines the degree for rotating pages; 0 doesn't do anything, and 90 converts portrait to landscape thumbnails defines whether mdc shall automatically create a thumbnail overview of the document: Choose "1" for yes and "0" for no. Please note that postscript files created on windows machines often cause errors. If so, we recommend the use of the png image format when importing documents. Please have a look at the FAQ
Start mlb	The mlb can be started on command line with the following parameters (all parameters enclosed in [] are optional): mlb [maddr/mport] [-t mttl] [-f file] maddr denotes the multicast address of a shared session the mlb should join after startup mport denotes the multicast port of a shared session the mlb should join after startup mttl denotes the multicast time to live of a shared session the mlb should join after startup file denotes a mlb document to be opened in a private workspace after startup Start the mlb by executing the binary within its installation directory - otherwise the mlb is not going to work properly! To start the mlb from an arbitrary path you will need a batch or script file that changes to the mlb home path and then calls the mlb itself. A sample script file can be found within the mlb-download package: after extracting the zip file there will be a subdirectory "sdr" where you can find a file "mlb" (Linux) or "mlb.bat" (Windows). Change the first line of this file to your mlb installation directory. Then place the file in a directory included in your PATH setting (i.e., a directory that is searched by the operating system for programs that cannot be found at the current path).
Start mlb with SDR	Alternatively, the mlb can be started via the multicast session directory (SDR) if there exists a corresponding session entry within SDR (a short description how to create session announcements can be found here): just click on the first "imedia" button. For this to work, you have to execute the following two steps: Copy the file "sdr2.plugin.S22.imedia.rtpi.mlb.mlb" that you can find in the sdr subdirectory of the mlb distribution into the plugin directory of sdr (e.g., "~/.sdr/plugins" for Linux or "c:\programs\mbone\sdr\plugins" for Windows) Copy the file "mlb" (Linux) or "mlb.bat" (Windows) that you can find in the sdr subdirectory of the mlb distribution into a directory that is included in your system PATH. Change the first line of this file to the installation directory of the mlb.
Manage and Join Sessions	If the mlb was not started via SDR or was started without command line options, the next step is to join the actual shared session by selecting "Shared Session..." in the file menu and entering the appropriate parameters (such as multicast IP address and port of the shared session). By clicking on the "Join" button, your mlb instance joins the shared session. In the "Participants" window (activated via "View" menu) you will now see a list of all participants present in the session. A newly started session is empty - add a page and start whiteboarding. Session IP Address is the IP multicast address of the shared session. Session Port is the port number of the shared session. TTL is the time-to-live of the shared session. Bandwidth defines the maximum transmission rate of the mlb. If local user actions threaten to exceed this rate, data transmission will be delayed artificially. Cue Rate specifies the percentage of intermediate mouse events being transmitted during move and change size operations. A higher cue rate results in a smoother display of user actions, but also increases the network load. Local Lag specifies the local lag in milliseconds. The local lag delays local user operations and is used to prevent short-term inconsistencies. A higher value will provide better consistency but will lower responsiveness to local user actions. State Storage defines the maximum length of time (in seconds) in which received and locally made operations are stored. Inconsistencies are repaired by timewarp during this period. Inconsistencies relating to a time further back in history cannot be repaired locally but by state request only. A higher value for the storage time therefore increases the probability that inconsistencies can be repaired by timewarp but places a higher demand on memory. Indicate Conflicts If enabled, all local and remote operations are checked if they conflict with each other (e.g., if the color of an object is changed by two participants simultaneously). A detected conflict will be displayed by a balloon-help window containing the list of all affected participants. Log Page Changes If enabled, the mlb creates a log file that holds the history of page changes within the shared workspace. For each change of the active page, an entry <PageID Timestamp> is written. This page history can be used to structure recorded mlb sessions by pages. A log file has the name pages_[multicast_date_timestamp].log. For easier management of frequent sessions, all session parameters are stored together with the name of the session. You can define new sessions ("New") and delete the parameters of existing ones ("Delete").
Setup User	Local user information can be entered via "Options" -> "User Profile". The cname is derived from the login name and the IP address of the hosting computer and cannot be changed. All data is stored in the file ".mlb_userprofile". Information about remote users can be retrieved by double-clicking on a user in the "Participants" window (activated via "View" menu).
Manage Documents	At any particular point in time, there can be at most one shared document, but more than one private one. New documents can be loaded or created via the "File" menu. User actions performed within the shared document are transmitted to all other participants, whereas actions within a private document are visible only locally. If you leave a shared session, the shared document is transformed into a private document. Thus, you can switch shared sessions without losing content. The current version of the mlb supports late-joining participants. For a late joiner, this means that all content created before his joining the session will be available. But to reduce the initialization delay, only those (old) pages are requested that are active or become active at a later point in time. Documents (shared and private) consist of pages and chapters. The hierachy of documents is visible in the "Documents" window (activated via "View" menu), and you can reorganize the document structure via drag&drop operations: pick up a page or a chapter with the mouse (click and hold left button), and release object at the target position (release left mouse button). Drag&drop can also be used to transfer pages or folders between documents. If an object is transfered to the shared document, it is automatically transmitted to all other session participants (including all "child" objects such as the graphical objects on a page). By double-clicking on a page or chapter, you can change its name. The numbering of chapters and pages is generated automatically. The active page can be selected either by a mouse click on the "Documents" window, by using the arrow buttons, or by operating the arrow keys ("up" and "down"; "Home" jumps to the first page). With the help of the "import" button (rightmost button below the document tree) it is also possible to import the topmost silde from a private document into the shared document, which is useful when giving a presentation from a previously prepared and loaded document. Documents, including all annotations the local user has made, can be saved in an sgml format and loaded again at a later point in time (via "File" menu). Each document loaded is appended to the document hierachy as a new private document.
Adjust View	The user interface of the mlb can be adjusted to your specific needs via the "View" menu. Besides enabling and disabling parts of the mlb's interface such as toolbar, document tree, and participants list, the zoom factor for the slides can be selected either by manual definition ("Zoom...") or by choosing the optimum size in respect to the window size of the mlb ("Fit Page to Window"). If you want to hide all tools and use the maximum available screen space for displaying slides, use the "Fullscreen" mode. While in "Fullscreen" mode, annotations can be made as usual (unlike PowerPoint). You can return to the regular display mode by closing the fullscreen window.
Thumbnail Overview	For easier navigation, a thumbnail overview of all slides of a private document can be generated (menu "View"-> "Thumbnails"). The overview reflects the current state of all slides and can be accessed via the "Thumbnail" folder in the document tree. The thumbnails of the slides are displayed on pages that have the same size as the pages of the document. If there are more thumbnails that fit onto one page, the thumbnail folder will contain several pages. The thumbnail folder can be organized either in "flat" or "original" hierarchy. When choosing the "original" hierarchy, the thumbnail folder will contain subfolders that correspond to the subfolders present in the original document and the thumbnails will appear in the subfolders they are contained in. With "flat" hierarchy, the original structure of the document is lost and all thumbnails are displayed sequentially. The thumbnail overview can be used to navigate within a document, either by using the "Arrow" keys and "Enter", or by double-clicking on a page. When importing a slide into the shared session, the corresponding thumbnail will be embedded in a grey box (see image above), and selecting the thumbnail will activate the appropriate page within the shared session. The thumbnails itself are not visible in the shared session, and a thumbnail overview can be created only for a private document. When saving a document, an existing thumbnail overview is stored, too. To save time during the actual session, we recommend to prepare thumbnail overviews in advance, e.g., using mdc. The thumbnail of a slides represents the state of the slide at the point in time the thumbnail was created. Any changes performed afterwards are not reflected. For an update, create the thumbnail overview once more.
Import / Export Documents	If ghostscript is installed on your system, the mlb can import (via "File" menu) Postscript and PDF-files. Since we rely on an external program, this feature of the mlb does not always work well. We recommend that you test the import of a document offline. Some postscript dialects can be problematic, especially when created under Windows (try the Apple LaserWriter driver). If an import fails, you have two options: (1) Convert the document page per page to an image format with an external tool such as ImageMagick's convert tool (available for Linux and Windows). Following, use mdc to generate a mlb document. With a simple script (e.g., ps2mlb.tcl) this process can be automated. (2) Try to repair the postscript file with the psutils (available for Linux). All documents (shared or private) can be exported in various file and image formats. This function uses the zoom factor that is currently selected, meaning that the images have the same resolution they are displayed with. It is also possible to create an html-document containing all slides and a thumbnail-overview. When choosing html as export format, the mlb creates a new directory that contains all files needed for the html-presentation. Starting point is "index.html".
Edit Documents	Create new pages either by pressing the "New Page" button in the "Documents" window or by using the "Edit" menu. The active editing tool (e.g., draw freehand line, draw rectangle, ...) is selected in the toolbar, and the tool's properties (e.g., draw color, line size, font size, ...) in the attributes bar. Newly created objects are displayed on top of all other objects present on a certain page. If you want to change this display order, use the "Raise" and "Lower" buttons. If you select an object, it is possible to change its properties, move it, copy it, or delete it. Most editing operations can be undone or redone, both in the shared and the private workspace. Normally, all local user actions performed within the shared document are transmitted to the other participants. To make private annotations within the shared workspace, activate the annotation mode (press annotation button in "Documents" window). Private annotations are visible only to the local user. As with the editing operations, page changes within the shared document are transmitted, too. If you want to browse through pages without disturbing other participants, deactivate the "Live Mode" button in the "Documents" window. Please note that if you are not in live mode, you will not be able to perform any editing operations.
Presentation Animations	Similar to PowerPoint, mlb presentations can be structured with the help of presentation animations. These allow to fade in and fade out graphical objects in a well-defined order. There are two modes, one editing mode for creating new and editing exisiting animations, and a presentation mode for giving the talk. 1. Prepare Animations Animations are subdivided into animation steps. A step holds all actions (fade in or out objects) to be performed together, meaning that a step is triggered by a single event (e.g., hit space bar). Activate the animations window by selecting "Animations" in the "Tools" menu. You are automatically in the editing mode. The animations window holds a list of all animation steps that are defined for the page currently displayed. Each step has a list of all actions to be performed. You can create new steps by pressing the "New Step" button (leftmost on top). Add an action to the activated step by selecting one or more objects and pressing either the blue "+" (fade in) or the red "-" (fade out) button. The object list of each step is composed of unique object identifiers. If you want to know which objects are referenced, select either a single object or a whole step of the animations list. Objects can be deleted from a step's list via the popup-menu (right mouse button). The same object can be used in different steps (e.g., fade out in first step, fade in fourth step, and fade out in fifth step), which allows very flexible animations. The ordering of steps within the animations list defines their execution order. If you want to change that order, steps can be rearranged by drag & drop. Animations are saved automatically if you store your mlb document, so that you can prepare your presentation in advance. 2. Give Presentation To give your presentation you have to switch into the presentation mode by pressing the "Presentation Mode" button (rightmost on bottom). The first animation step defined is executed automatically. Thus, the first step should hold a fade out action for each object you want to hide at the beginning of your animation. The respective next step can be triggered by hitting either the space bar, the (page) down keys, or by using the "up" and "down" buttons of the animation window. If there is no next step on the active page, the next page is displayed automatically. The presentation mode is left by pressing the "Presentation Mode" button once more.
Telepointer and Telebox	A telepointer creates a common point of reference within a shared session and provides, basically, a shared mouse pointer. It is used to visualize mouse movements by the local user to remote participants, e.g., to highlight certain objects. You can activate the telepointer by pressing the "Telepointer" button of the toolbar. The mlb allows each participant to have its own telepointer. To avoid confusion, it is advisable to choose different colors ("Options" -> "Telepointer" menu). Whenever a participant uses a telepointer, a telepointer icon in the correct color is displayed next to the participant's name in the participant list. For highlighting a whole region within the shared workspace, you can use the telebox that can be drawn by pressing and holding the right mouse button. The telebox is drawn in the same color as the telpointer.
Feedback	With the help of the feedback tool you can evaluate certain parameters such as technical issues (e.g., audio and video reception quality), but also parameters concerning content and quality of the talk itself (e.g., if the talk is detailed enough). Activate the feedback tool via the "Tools" menu. To create, edit, and delete evaluation parameters, press the "Q" button in the "Feedback Tool" window. The "Feedback" window contains a list of all created questions. Select the visible parameters by clicking on the appropriate check box. If you want to create a new parameter, click the "Create" button and enter the number of possible answers. Next, you need to assign semantic meanings to the possible answer values. Participants can now give their vote by using the slider in the "Feedback Tool" window to select a value. The result of all votes is displayed as an average. Edit or delete parameters by selecting them from the list and clicking on the appropriate button.
Voting	The voting tool allows you to survey opinions of the participants of a mlb session or to place exercises and evaluate the results. Questions can either be multiple choice or text (i.e., plain text answers) questions. There are two main difference to the feedback tool. First, text questions are possible, and, second, results of multiple choice question are displayed in more detail. Open the voting tool window via the "Tools" menu. The voting window holds a list of all questions available. The following actions are possible (in the order of buttons from left to right): Create a new question (text or multiple choice), delete the selected question, give your own answer to the selected question, and view the results of the selected question.
Hand-Raising	In most videoconferencing scenarios, the number of available audio and video channels is highly limited, making direct collaboration among participants quite difficult. For example, in a teleteaching session between two lecture rooms, it is nearly impossible for the referee to notice the raised hand of a student in the remote lecture room, especially if the audience is rather large and the displayed video small. The hand-raising tool allows a controlled procedure in which a participant raises his hand and the referee calls upon a certain person. The hand-raising tool is integrated into the participants list ("View" menu). To raise your hand, press the "Raise Hand" button in the lower left corner. All participants having raised their hand are marked with a blinking orange dot next to their name. You can also have a popup-window notify you about the raised hand of a remote participant by activating the upper-right button. If you decide later on to withdraw your hand, press the "Lower Hand" button. A participant can be called upon by selecting his name from the raised-hand participant list and pressing the "Call" button. The participant called upon is notified by a popup-window.
Chat	For short discussions (e.g., about technical issues of the session) it may be useful to fall back on the chat tool. It can be activated via the "Tools" menu. Enter your nickname and start typing your text messages.
Application Launch	The application launch tool can be used to start external programs synchronously for all participants of a mlb session. A lecturer, for instance, might want to show a java animation about routing algorithms to clarify a certain slide. Activate the application launch window via the "Tools" menu. The window contains a list with all applications prepared to be launched. The following actions are possible (buttons from left to right): Create a new application, edit the selected application, delete the selected application, and start the selected application at all sites. When creating a new application, the following fields have to be defined: "Name" is the display name of the application, "Executable" specifies the actual program binary, "Parameters" (optional) defines parameters the binary is to be called with, and "Local Path" gives the local directory path where the program is stored. While the first three paramters are equal for all participants, the local path has to be entered individually if the path of the application is different form the mlb path. Please be aware that remote launch of applications is a security risk and that there are no mechanisms included to avoid the launch of evil programs.
Local Recording	The mlb offers the possibility to record private sessions locally in the AOF (Authoring On the Fly) format. In addition to the slides (including all annotations), the audio of the referee is recorded as well. The AOF recording mechanism aims at the production of offline courseware, to be published as a CD-ROM. A special viewer is needed to replay recorded sessions. Activate the AOF tool under the "Tools" menu. Please refer to AOF for more information.
Shared Recording	The communication model of the mlb is based on RTP/I, an application-level protocol for distributed interactive media (e.g., networked computer games, animations, and shared whiteboards). To be more specific, RTP/I is a protocol framework for the transmission of application data and the management of meta session data such as participant information. The RTP/I framing captures information common to all distributed interactive media. For instance, it distinguishes between state and event ADUs (Application Data Units). Please refer to RTP/I for a more detailed description. Thanks to RTP/I, it is possible to develop generic services applieable to all distributed interactive media that make use of RTP/I. An important example is the generic RTP/I recording service IMoD (Interactive Media on Demand), which is able to record and play back arbitrary RTP/I sessions in synchrony with RTP media streams (e.g., audio and video).
Client for Handheld Devices	We have implemented a mlb client for personal java running, for example, on Compaq iPAQ's. Via a client-server architecture called UCE (Ubiquitous Computing in Education) mobile clients can be connected wireless (Wavelan) to a mlb session. If you are eager to learn more, feel free to contact Juergen Vogel (vogel@informatik.uni-mannheim.de) or Nicolai Scheele (scheele@informatik.uni-mannheim.de).
Tips & Tricks	Freeze images Activating this option ("Edit" menu) prevents images from being moved or resized, which is useful if your slides are imported as images and you annotate them. Freeze document tree Activating this option ("Edit" menu) disables drag&drop of document tree objects (i.e., pages and folders), which is useful during presentations once your pages are in the correct order. Participant hints Activating this option ("View" menu) attaches a small balloon help window to graphical objects currently being edited. This windows contains the name of the editing participant. Config file The most important parameters of the mlb (such as networking options, window size, and view options) are saved in the file ".mlb_config". It is helpful to have a config file prepared before starting a session. User Profile All information about the local user (as defined in option menu) are stored in the file ".mlb_userprofile". It is helpful to have a correct user profile at hand.
Contact	Please send your comments and bug reports to: Juergen Vogel (vogel@informatik.uni-mannheim.de)