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The question is, at what point in the future will digital signage fall victim to wireless digital signage on our mobile devices or wireless head-worn (glasses) displays?
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When considering an HD digital distribution system, ensure all products in the system are HDCP-compliant.
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Various digital signage software packages include schedulers that will automatically change the source content based on a specific time and date. This is convenient and eliminates the need for manual switching.
“Digital signage, [is] a form of electronic display that shows television programming, menus, information, advertising and other messages” (Wikipedia). It seems that with every turn we are in eyeshot of some form of digital signage. Frequent flyers are accustomed to gathering around displays seeking flight information and shoppers are presented the latest products in the forefront of a high-contrast visual marketing display. It seems as if the art of verbal communication is being challenged by texting, email, and digital signage. We are a visual society now, like it or not.
The benefits of digital signage, though numerous, present many challenges when it comes to digital AV distribution. The old days of distributing TV with simple RF splitters and coaxial cable are almost gone. Digital high-definition distribution, like residential high-speed Internet service, has become the norm.
Is there a right way to distribute digital HD content? Are there things to be aware of? The answer is—yes.
Acronyms to know
Let's start with the first of three four-letter acronyms: HDCP. High-bandwidth digital content protection (HDCP) is a form of digital copy protection. The purpose is to prevent HD content (movies, etc.) from being copied, duplicated and sold. It protects the owners' or authors' product from piracy. However, the extensive algorithm used to protect said content questions all aspects of the digital system to ensure no device has been modified and able to copy the HD content. This process is quite skeptical and not easily fooled.
That said, manufacturers of HD players and displays have engineered their products to properly and legally handle HDCP and ensure the copy protection process is honored.
RECOMMENDATION
When considering an HD digital distribution system, ensure all products in the system are HDCP-compliant. Too often, troubleshooting an HD system results in finding a product in the system that is not HDCP-compliant and that prevents the HD content from being delivered.
HDCP, EDID, HDMI, HDBase T…. Confused yet?
Extended display identification data (EDID) is information stored in displays that replies to the source (DVD player, etc.) the display's resolution capabilities, manufacturer, make, model, serial number, etc. This information is embedded in the display data channel (DDC) of the digital signal (HDMI, Display Port, DVI). The purpose for EDID is to ensure the display and system can work in unison. In other words, to make sure they know each other and configure themselves to work together.
Now, HDCP keeps a keen eye on how many displays are attempting to show or project its content. This information is derived from the EDID process. If HDCP “sees” too may displays connected to the source (exceeding the number of keys the source is programmed to issue), it will send a pretty green-screen image and a nasty note stating an HDCP issue has occurred.
Confused yet? Are you missing the good old days of “standard definition” and coaxial cable?
A nice feature of digital media is the High-Definition Multimedia Interface (HDMI) connector and cable. The 19-pin connector and cable carry numerous signal types: video, audio, consumer electronics control (CEC), voltage, hot plug detect, and other types of communication. However, HDMI is often mistaken as a video signal. It is much more. In fact, HDMI and DVI share the same digital video type. HDMI includes the additional channels of communication and control in one jacketed cable. No more coax plus a three-conductor RCA cable. The professional AV industry had to adopt the consumer HDMI connector but has improved its reliability by creating secure brackets that support the flat connector once plugged into a device. (See Extron LockIt at www.extron.com.) “Oh, so that's what that little screw above the HDMI jack is for…. ”
Crucial components
Now that we have briefly described HD delivery, HDCP, EDID, and HDMI, let's consider what components are required to properly distribute HD content. It's easiest to start from the display and work backwards when designing an HD distribution system. Though most all displays sold today are capable of displaying 1080p resolution, it never hurts to make sure. Digital media experts will quickly tell you the weakest link in any digital media system is always the sink (display or projector). Remember, the display communicates back to the source (DVD, etc.) its EDID information that includes its highest resolution capability. When multiple displays are connected to a common source, the source will deliver a resolution equal to the highest common display resolution. In other words, if you have six displays in your system and one display's highest resolution capability is 720 then the source will deliver 720 so all displays can present the content.
RECOMMENDATION
When considering an HD digital distribution system, ensure all displays share a common highest resolution capability. Content resolution will be equal to the highest common resolution capability of the displays.
Have we mentioned there are no Y-cords for digital video? Be aware. To properly connect multiple displays to a common HDMI source, an HDCP-compliant distribution amplifier or digital matrix is required. These are active electronic devices and [they] vary in price and capability. When considering the appropriate matrix or distribution amplifier, refer to Recommendation #1.
Now, for the important factors. Digital media distribution, by nature, has length or distance limitations. Like computer networks, digital media (HDMI) is subject to short cable distances due to the digital signal (packets) and bandwidth. The longest HDMI cable recommended for use is 50 feet. A 50-foot HDMI cable is robust and can be expensive. The most common HDMI cable lengths are 3, 6, 9, 12 and occasionally 25 feet. That said, the question begs, how do you distribute HDMI beyond 50 feet? The answer is HDBase T. HDBase T is a technology (chipset) used to transmit high-definition audio-video over category (CAT5 - CAT6) cable. This technology is used by numerous AV manufacturers in their digital media products. It is reliable and quite popular. Using CAT5 or CAT6 network cable and RJ45 connectors, HD content can be transmitted to digital signage displays very cost effectively. However, as mentioned above, there are cable length limitations. [For example,] 330 feet (100 meters) is the rule of thumb.
RECOMMENDATION
When considering HD distribution, the distances between the source electronics and the displays is important. A well-designed digital signage system must include the proper infrastructure: conduit, boxes and power, and careful consideration of cable lengths.
The easiest part of digital AV distribution is the source content. Once all the technical aspects are addressed, it's time to send the content. The most common forms of content are slide shows, web pages and live (streaming) media from a production system.
Various digital signage software packages include schedulers that will automatically change the source content based on a specific time and date. This is convenient and eliminates the need for manual switching.
An alternative to building an AV distribution network using matrix switchers, distribution amplifiers and category cable is the equipping of each display with a network-based media player. The media player is mounted on the back of each display and connected to a network (new or existing). The HDMI output of the media player is connected to the HDMI input on the display. This form of AV distribution is quite easy to implement and manage. Content (data files) are pushed to the media player(s) from a computer via the network. The capacity of the media player will determine the maximum file size(s) the player can store and play. Media players are especially popular in retail, hospitality and corporate digital signage applications where “live” video is not required. Coupled with network-based scheduling software, the media player approach is cost-effective, scalable and easy to install and manage.
Texting, email and digital signage—it is evident [that] non-verbal communication is ruling the day. The question is, at what point in the future will digital signage fall victim to wireless digital signage on our mobile devices or wireless head-worn (glasses) displays? Can you see it now, everyone walking around, staring into space and talking to someone that is nowhere around? At least we won't have to worry about HDCP, EDID and 300-foot cable limitation any longer.
