in July 2007
A LAN-Based AV Presentation Primer
By Steve Woolley
A proposal that implements common TCP/IP protocols.
|Bird's eye view of Republic Polytechnic in Singapore, which features 720 classrooms that can be accessed wirelessly.
A simple “connect and present” solution has long been the Holy Grail of the audiovisual system designer. Unfortunately, the consumer origins of most source and display signals, cable media and/or connectors required specialist interfacing hardware designed to buffer, scale and switch sources to displays.
High definition (HD) has introduced more interfacing headaches, where the customer and facilities manager have to pick the winner of the new Format Wars:
• HDTV: 720p vs. 1080i vs. 1080p
• Scaling: Legacy 4:3 vs. consumer displays at 16:9 (1366x768, 1920/1080) vs. PC/Mac displays at 16:10 (1440x900, 1680x1050, 1920x1200, etc.).
• Connectivity: Analog (composite video, S-video, component video and VGA) is migrating to digital (DVI, HDMI, SDI), but complicated with manufacturers offering electrically balanced interfacing options using UTP. The UTP interface solutions use low-cost cable, but high-cost/proprietary interfaces, and introduce new technical problems of color smear and timing.
Over the last 20 years, AV interfacing has created a new industry with its own jargon, training and trade shows. HD has caused the latest AV interfacing product catalogs to balloon into the size and weight of the Los Angeles telephone directory. The facility manager is in gridlock, unable to decide which manufacturer or format will dominate and, thus, provide a viable solution for the next five to seven years.
The problem is particularly critical for the costly cable infrastructure; i.e., should the system use traditional RGBHV solutions and risk analog obsolescence, opt for costly 19 core DVI/HDMI with distance limitations and a question mark of its long-term viability, or convert to UTP and be locked into one vendor’s proprietary signal protocol?
Is There A Better Solution?
Here, we’ll propose a much simpler solution: a LAN using common TCP/IP protocols. Consider the customer’s real-world needs:
• A laptop or PC running WinXP or MacOSX and a desktop application represents 70% to 80% of presentation material. This includes interactive whiteboards.
• DVD covers most portable media and an archive HDD covers most stored media. Both can be played or streamed from the presenter’s laptop.
• Microphone(s) are required for larger rooms.
• VHS, visualizers, etc., represent 5% to 10% of presentation material and are of declining relevance.
• Cameras are used in videocon-ferencing and distance learning applications, but HD format cameras are available now, so legacy analog cameras (composite video and RGB) will disappear.
The most important source is now the presenter’s laptop, which accounts for 70% to 80% of presentation material.
If the DVD/CD player in the laptop is included, then the presenter’s laptop will provide a single source for more than 90% of material.
For historic reasons, the VGA port became the defining laptop connection. A considerable proportion of the interfacing manufacturer’s catalog is dedicated to taking the signal from the VGA port, buffering, scaling, switching, rescaling, rebuffering, before finally connecting to the display. Sophisticated touchpanel control systems have been created to try to provide the presenter with a simple user interface.
If we ignore the interfacing technology and take a bird’s-eye view of the customer’s real needs, then a simpler solution would be to transmit the presenter’s active desktop as a stream from the LAN (or WiFi) port using standard TCP/IP protocols. The stream would be received by a LAN-enabled display, or to a LAN set-top box at a legacy display. Just login to the display and present.
The Rest Is Software
Once LAN connectivity is used in place of the VGA port, then both the presenter’s desktop (i.e., the source) and the display are just endpoints on the network. The rest is software! The LAN-based approach also offers the following benefits:
• No need for hardware switchers. Because all LAN ports can have an IP address, the LAN provides switching capability at no additional cost.
• No need for hardware scalers. The chipset inside the presenter’s laptop provides a powerful scaler. Instead of using a VGA signal at full resolution (say 1400x1050), then destroying/manipulating pixels in a costly hardware scaler to match a 1024x768 projector, the simpler solution is to match the presenter’s desktop to the resolution of the display. This scaler capability is built into the ATi, NVidia, Intel and other video card chipsets.
• No need for a touchpanel control system. The big disadvantage of a touchpanel GUI is the “one size fits all” approach, where each meeting room has a single touchpanel with many pages to control all aspects of the system. A better approach would be Yahoo Widgets or Mac Dashboard, which allow every presenter’s desktop to have a customized control screen to suit personal usage patterns.
Once the overall concept had been defined, the next step is to envisage and define the modules and accessories required to provide the presenter with a fully integrated solution.
Three core elements are required for the concept to work:
• Some form of “client software” that would reside, for example, in the presenter’s laptop and would convert the presenter’s desktop image into LAN data.
• Display interface hardware and software would take the data from the presenter’s laptop and convert it back to a video and audio signal for connection to the display.
• Server software to provide directory integration (i.e., common login process) and asset management.
|The login process can be integrated with the client’s Active Directory. If there are many presentation rooms available on the network, this menu will simplify the selection process.
||The operator should also simply just click, “Display Me,” and the Presenter’s desktop will appear at the display.
The client would be a small software application running in the presenter’s laptop. One option is for the client to normally be loaded by the systems administrator, when the laptop is set up with the corporate or campus firewall, VPN, etc. For guest presenters, the client would be downloaded automatically via WiFi, when the presenter logs onto the display interface. The client logically would provide the following functionality:
• Desktop image transfer
• Mouse image transfer
• Media: Most media files (DVD, QuickTime, WMV, AVI, etc.), have to run at 24 to 30 frames a second. Uploading these images from the desktop would be an unnecessarily processor-intensive solution, so an alternative solution is to locate the media player at the display interface, rather than at the presenter’s desktop. If the display interface has memory (e.g., HDD or USB port), these options are available to the presenter:
Presenter file upload and play: This uploads the media file from the presenter’s laptop to the display interface memory and uses the media player inside the interface. This is slower, but allows file sharing with other participants.
Presenter streaming: Rather than upload, the file is streamed to the display interface. This allows even the largest DVD file to start playing within a few seconds.
Archive: Uploading or streaming can be initiated from an archive server on the network, as well.
Although the media player is in the display interface, the media player controls (play, pause, stop, etc.), would have to be operated remotely from the presenter’s desktop.
• Control: The client will have to provide the presenter with controls for login, room selection, presenter/input switching, media transport controls, etc. The GUI (graphical user interface) will be critical and Yahoo Widgets provides an excellent graphical template for control module design.
The display interface is required to connect a LAN signal (carrying the presenter’s desktop/streaming data) to the display VGA/DVI ports. In addition, the interface should connect to the display control port (usually RS232, USB or LAN) to provide asset management, and control and monitoring of the display. Two form factors of display interface would be required: a small set-top box for video projectors (the set-top box would affix to the projector bracket) and a slot-in module for the professional plasma and LCD displays.
The interface LAN port would connect to the user’s LAN (or VPN). If a standalone display solution is required using WiFi as the connection, then the internal 802.11x port would be used.
A DVI/VGA port would connect to the display video input. The 3.5mm audio port can connect to the display loudspeakers (or external amplifier/loudspeakers) and one of the USB ports will be used to control the display (using a USB serial cable for legacy RS232 ports on older displays). The power connection would be shared with the display.
For plasma and/or LCD displays, it would be necessary to develop a thin form factor interface package, preferably one that would be compatible with the slot(s) available at the rear of most professional PDPs.
Ideally, both the set-top box and slot-in module would require:
• Embedded Operating system
• Custom application with remote/central updating capability
• Media player, loaded with common codecs (WMV, QuickTime, AVI, Flash, Shock, etc.)
• Fast graphics processor
• External ports and firmware drivers for external control of display, curtains, drapes, etc.
• HDD for media files and file sharing
• WiFi port for standalone operation
• Compliance with corporate/campus VPN, malware, firewall, antivirus and other systems administration settings
• Compliance with all likely data encryption needs
• Compliance with closed captioning and other ADA requirements
For small systems with a limited number of rooms, the central server may not be required, and the presenter can simply connect to the display directly using a common login (e.g., User1, User2, etc.). However, we can anticipate that most organizations, especially those with a larger number of meeting rooms or classrooms, would prefer to have a login process integrated with their existing active directory. By integrating directories, the same network/VPN login and password will be used for the AV presentation system.
Another advantage of the server software is the creation of a central asset management and logging solution. This is particularly important when dealing with a large number of displays. For example, the need for simple monitoring of usage patterns, lamp life, display status (working/not working) and a centralized method of switching all displays off are key elements of asset management.
A customizable Alerts Page would be required to display all relevant systems components as required for each facility.
For the control of the external room environment, it would be desirable to have available simple power relay (curtains, screens, drapes) and power dimming (lights) interface units.
Speech Reinforcement will be essential for rooms with more than 30 participants, or venues requiring ADA compliance. However, speech reinforcement over a LAN requires careful consideration because network latency can cause intelligibility issues.
Although more than 90% of material will
be generated by the presenter’s laptop (i.e., desktop application,
streaming media file or DVD drive), there remains a need to
connect legacy source material to the display. For example,
this could be copyrighted VHS material that cannot be transferred
legally to DVD, or simply the preference and comfort of a specific
presenter who uses transparencies and a visualizer. Whatever
these may be, it is valuable to accommodate all the likely needs
of users. In addition to simplicity and user friendliness,
the LAN-based solution offers significant benefits throughout
the installation, integration and service processes:
• Installation (cables, connectors, parts): Consider the modern educational establishment with 100-plus seminar rooms and 30-plus students in each seminar. More than 3000 VGA/DVI points would be required to create an interactive classroom environment. Because students will be presenting more of their work through laptops, PDAs, etc., WiFi LAN connectivity would eliminate the requirement for any VGA/DVI points, representing a significant cost saving in cable, table-wall plates, interfaces, switchers, etc.
• Fast deployment: A LAN-based solution dramatically reduces labor and programming costs. A typical interactive classroom or boardroom requires more than 200 hours of skilled labor to design, install, program, test, commission, document and deliver through to final user training and handover. In contrast, the LAN solution has trivial room connectivity (power, LAN) and simple integration (set the IP address).
• Retrofitting: Retrofitting is simple and cost effective. By using a LAN/WiFi infrastructure, it is not necessary to tear apart the costly boardroom walls and floors to retrofit an AV presentation system. The set-top box connects wirelessly to all presenter laptops, and sits at the existing projector position. It will share the power socket with the projector and the only external connection required is a LAN point.
One Of The Biggest Problems
For the education sector, one of the biggest problems is refitting classrooms between semesters. With a LAN solution, members of the faculty staff no longer are the inadvertent “testing and commissioning crew.”
• Existing investment: The LAN solution will work with existing AV presentation systems. The LAN set-top box does not care which model of projector is installed. Thus, an existing investment in equipment is not wasted.
• Maintenance: Costs are reduced dramatically. Consider the earlier-mentioned 100-plus classroom example, each with 30-plus student VGA points. Within three months, the facilities manager would require a maintenance crew just to repair VGA points. A WiFi connection eliminates this problem.
• Asset management: Because the set-top box is connected to the various models of projector, it can SMS/email the facilities maintenance staff (or service provider) if a projector is faulty or the lamp is at end of its life.
An alternative to the set-top box for projectors, or the slot-in module for plasma/LCD displays, is the WiFi-enabled projector. These are projectors with a WiFi port that can accept active desktop images and/or streaming media. Conceptually, they work in a similar fashion to the proposed set-top box solution and employ a “client” software routine loaded into the presenter’s laptop.
However, there are significant disadvantages to the WiFi projector approach:
• Single Client, features and compatibility: The ideal solution has a single “client” and will work with any manufacturer’s projector. In addition, the client will work with both current and legacy projectors.
However, projector manufacturers are making their client software incompatible with other manufacturers’ products. Even projectors bought at different times from the same manufacturer often will have incompatible presenter client software and display firmware. This issue defeats the simplicity of the LAN concept and will require a high degree of technical support from the facilities department. For example:
• Every presenter laptop would require one or more clients from each projector manufacturer. For example, the Epson client will not work with the Panasonic, InFocus, Sony or NEC projectors and vice-versa, so the presenter could end up with six, eight or 10 software clients loaded into his laptop in order to connect to projectors purchased from different suppliers at different times.
• Even if the customer commits to a single projector manufacturer, later models may require a different revision of the presenter “client,” i.e., one that is incompatible with older projectors. It may be too early to predict a trend, but projector manufacturers currently have incompatible “clients” between earlier and later models.
• With multiple clients and multiple manufacturers, the presenter would have the headache of determining not just which manufacturer’s projector, but also which model of projector, is used in each room, and then pick the right client from their six, eight or 10 clients.
• Different projectors have different features, so the presenter would be quite confused over what he can do in each boardroom or classroom. For example, Projector A cannot stream video media, Projector B can handle MPEG1 and MPEG2, Projector C can also do MPEG4, and maybe QuickTime, Projector D has poor mouse speed and thus real time pointer speed, Projector E has long refresh times for the active desktop, but allows staff/student priority control, etc.
The ideal solution has one client that will provide a simple and consistent presenter interface with all critical features, i.e., real time mouse movement, fast desktop refresh and can play any media, such as MPEG1, MPEG2, VOB-DVD, QuickTime, AVI, DivX, Xvid, WMA, WMV, MP3, Shockwave, Flash, etc., etc.
• Priority levels: Many customer usage patterns require two levels of priority, such as moderator/participant in the corporate sector and staff/student in the education sector. Few of the projector solutions have a priority option, so control of the presentation would be difficult.
• Unlimited Participants: The set-top box can have an unlimited number of participants (or students) in any meeting room or classroom. However, WiFi-enabled projector solutions vary considerably, from only one presenter, to eight presenters, to unlimited presenters.
• Active Participant switching: In a classroom of 30-plus students, it is necessary to queue and switch the students to the display. Most projectors lack this feature.
• Macintosh: A Pentium Dual Core Mac OSX client is required. Many projector manufacturers do not offer this option.
• VPN: VPN is essential for large corporate and campus solutions. Most WiFi projector clients lack the protocols required to implement VPN.
• Active Directory Integration: Separate login processes for corporate/campus networks (i.e., one for general network use and one for the AV presentation system) would create a nightmare of coordination for the system administration staff. A LAN solution would be designed to integrate the AV set-top box and “client” with the end user’s “active directory,” so the presenter will use the same common login procedures. Most WiFi projectors require a login process separate from the system admin-istrator’s directory
• Fast performance: The ideal solution will offer fast updating of Active desktop, Mouse Pointer, Streaming, etc.
• Wired and wireless LAN connections: Most WiFi-enabled projectors offer only a wireless connection, and some establishments (particularly secure government buildings) require wired LAN. The set-top box solution can offer wired or WiFi, and accommodates all encryption solutions from 64 bit to 256 bit.
• Firmware/software upgrades: All systems upgrade firmware and software to fix bugs and add features. The set-top box can be upgraded as a one-time fix from a central location. Most WiFi-enabled projectors don’t have the capability of having their firmware upgraded; those that can have to be upgraded individually. This is a significant problem for large corporate or campus systems, for example, with 100 or more projectors.
The solution should be:
• simple to use. Just login and present: Whatever is on the desktop appears on the display.
• future proof. The solution has to last for five to seven years. The ultimate limitation should be the end user’s display
resolution, not the cable infrastructure or proprietary interfaces.
• fast and cost effective to deploy. The solution should not take more than half a day to install.
• simple to retrofit, i.e., no specialist cables and connectors required, and minimal disruption to interior finishes.
• an IEEE802.xx LAN solution from endpoint to endpoint, including low latency speech reinforcement.
An industry veteran, Steve Woolley is president of MTSI—Media Technology Systems, Inc. He has traveled the world as tour manager and sound engineer, and developed and marketed products that have established standards for performance and value