Previously, ActiveDeck was able to stay in sync within about 4 seconds between the PowerPoint computer and it’s neighboring iPads. However, this wasn’t good enough for us- our background is in show control systems and frame accurate video playback systems. We have a curse of over-analyzing every video playback system we see for raster tear, frame skips and sync problems. Given that ActiveDeck solely relies on the internet, we thought 4 seconds was pretty good, considering. But we wanted to make it much, much better.

We thought about the best way to improve the latency, and our initial thinking leaned towards a local network broadcast originating from the computer running PowerPoint, but that introduces issues on WiFi networks, especially those you would find in hotel ballrooms. VPN to the cloud service would be another option, but adds lots of complexity.

We ended up using pure HTTPS communications (no sockets, no VPN, no broadcasts) to and from the cloud servers with the use of some clever coding. If the iPad has internet connectivity, it will be in sync.

Check the video out, this is over a cable modem internet connection and a plan Linksys WRT54G access point. Our Windows Azure servers are at least 13 router hops from our office. The beautiful part is that the sync messages are tiny and this will scale to hundreds of iPads.

-olaaf

www.activedeck.com

Following up on the project involving a 100 iPads, a couple
of magazines/blogs picked up an article written by David Steinberg about the
project. It can be found here:

http://www.infocomm.org/cps/rde/xchg/infocomm/hs.xsl/17049.htm

The project was pretty cool (though under enormous time
pressure) and the concept of using iPads as audience participation devices has been
getting some traction recently..

The 3Byte R&D lab recently purchased a Microsoft Kinect to play with. We didn’t mind the fact that we don’t have an XBox to plug it into because Code Laboratories has published an SDK which allows you to use C# (and several other high-level languages) to access the camera feed. In fact, the test app that they distribute is very cool for immediately figuring out why this device is different than a normal web cam:

In addition to providing a normal color camera video stream (with red, green, and blue pixels), it also provides another dimension (literally) of depth information in a separate parallel stream. The picture above is me sitting at my desk, and the depth feed has been colorized to give a rough indication of where different objects are in the frame.

So, how do we do something useful with our new toy?

Read More >>

Have you ever wondered what 106 iPads look like when packed as densely as possible? Here is a picture:

For a recent project, we developed a synchronized iPad display app. The project was to support a presentation with some new method of interacting with the participants. The designers liked the idea of handing out ipads to which they could “push” content they wanted, when they wanted.

So, we fired up xCode and built the iPad app. The application is made up of several modes of operation while the main mode is to display content driven by the presenter, so that on cue all of the iPads display new screens without any interaction by the person holding the iPad. This looks pretty awesome when it gets triggered and you can see all of the iPads change their screens at once.

Other modes are sort of like tests or drills, where the users complete a quiz and then submit that data to the presenter. We have another application there that creates graphs based on the statistics from all of the iPad users to which the presenter can speak to when projected on a large screen in the center of the room.

When we set out to design the system, we had to think through the potential bottlenecks. Our main concern was network latency, so after some research we specified the best wireless access points we could find- Ruckus Networks. See these links:

http://www.ruckuswireless.com/

http://www.tomshardware.com/reviews/beamforming-wifi-ruckus,2390.html.

We ended up with 5 access points and a network controller on a gigabit network. Worked great (a little bumpy the first day of the presentation to due to a faulty access point).

Next, we created a back end system where the content would be stored locally, yet able to be updated during the presentation. Using IIS, we posted the images and XML files on a local (to the event network) webservice. We then wrote a multi-threaded socket server on another computer that was dedicated to triggering page turns, mode changes, and initiating fresh content downloads to the iPad.

Here is a video during some initial sync testing, this is all running from one access point, and triggered by Chris and his PC.

Computers in AV Systems

All of the AV systems I’ve worked on recently include at least one computer. Because Windows computers are so general-purpose and typically inexpensive, they can be used for interactive touchscreen kiosks, video playback, audio playback, or many other useful functions.

However, one thing computers don’t do well, is listen to control systems (at least out of the box).

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As the IT admin and part owner of a software startup, I’ve had to manage multiple servers and services. The domain controller is SBS2008, a WatchGuard firewall setup to use RADIUS to authenticate VPN against active directory, a subversion repository, a MySQL DB backing a redmine installation, multiple MS SQL Server DB’s to back various development projects with SA accounts, an internal FTP, a slew of other local services, all in addition to the default local admin logons, bank account logon’s, QuickBooks, Amazon, go daddy, insurance websites, etc. The list goes on for about 40 discreet user accounts and passwords. Then, I have my personal passwords to deal with, like my iTunes account, Gmail, etrade, quicken, bank account, facebook, linked in, home computer, etc.

In addition, for each of our consulting project installations, we have a slew of new passwords and user names for various computers and systems.

I had a simple system in 2000 or 2001- use the same password! Of course, this isn’t very secure, and it never quite worked- each system or service had a slightly different password policy.

So, I started using a password management system. Meaning of course, an excel doc with all of my passwords.

Then in 2009 I took classes for an MCITP program (the windows server admin certification program, they changed the name from MCSE for some reason), and one of the lecturers was a security expert who spoke about how nearly everyone uses “1” or “!” as their number or special character in a “complex” password. I was taken aback, because sure as hell I was doing that. He spoke about the need to use a password management system and to use passphrases. Also, he said it’s also okay to write down your passphrase on a post-it note and put it in your wallet.

So, about passphrases and the wallet thing first. The reason passphrases were better than a simple password is that they are long, yet simple to remember. The lecturer spoke about how windows XP and server 2003 used an LMhash, which broke your password into two uppercase zero-padded 7 character halves. So, it was super easy to crack with a brute force or time memory trade off algorithm- for example, this free application can crack LMhash passwords in a snap http://ophcrack.sourceforge.net/ . I cracked my home computer logon account with this software and freaked out about how easy it was. There is even a paid CUDA accelerated version, for those with big nVidia cards.

The deal with a passphrase was that it is typically longer than 14 characters and really hard to brute force unless you are the NSA. Imagine your password is “don’t forget the Ajax”. That is 22 characters, really fast to type, and really hard to crack. In addition, if you wrote it down on a post-it note and kept it in your wallet, there is a good chance the guy who stole it thinks it’s a shopping reminder, not a password.

However, you can’t remember so many different passphrases for so many different sites (I won’t even talk about how bad it is to use the same password for every account). Here is where a password management system comes into play.

For Three Byte, I set up Password State http://www.clickstudios.com.au/ it’s free for 10 users or less, and totally awesome. It allows you to authenticate against Active Directory to access the password site, and from there you can access passwords and user names for your other services. It requires SQL Server and IIS. This system used 256 bit AES encryption in the database, and some local .NET methods to further obscure the password. It allows you to share your passwords with other users, and it logs each time the password was copy-clipped or viewed. It allows you to set time limits on the passwords, so you can keep them fresh. Just what the CIA needs, I think. I’ll use it for all my major AV installations and recommend its use to anyone who needs this kind of system.

FYI, this screenshot is copied from the clickstudios.com site, so no hacker can see the user accounts we actually use!

My buddy Geoff who is a pilot in the Air Force tells me about super stringent password requirements, such that many people create a new password by simply hitting the characters on the keyboard from left to right (starting at 1), up to down (ending at z),  alternating with the shift key to generate the password. If only they were taught why and how to secure passwords.

For more resources on secure passwords, just google it.

Recently I had to build a desktop application that allows users to watch video files. After becoming familiar with Microsoft’s Windows Presentation Foundation, this seemed to be really easy: .NET Framework 3.5 provides a MediaElement control which you place in your UI and then assign a source file to play. It is simple to build your own transport controls right into the UI that match your design and there are lots of examples of how to do this on MSDN.

As I guessed, this was easy to wire up and my first pass looked like this:

WPF Example Using MediaElement

Here is a complete Visual Studio 2008 project (MediaElementPlayer) that you can build to see how it works.

Great.  Game Over, right?

Read More >>

About a year ago or so, I discovered this site for helping with software development problems:

www.stackoverflow.com

It’s a completely free, community powered site for asking and answering questions related to software development. It was made for experts, by experts. It turned out to be an amazing problem solving resource, and shortly thereafter www.serverfault.com and www.superuser.com were opened up, and now have a huge user base. I encourage you all to take a look at the quality of questions and answers.

The founders have decided to open up to the internet community and ask for ideas to start up new sites. There are ideas for sites from mythology to raw food to industrial control systems.

I’ve put a proposal out there for a site to cater to the community of AV professionals. The concept being this is where you ask the tough questions, and help out people with tough problems. I need people to sign up and back the proposal, as well as to ask sample questions to see if the quality meets the par. This thing needs a critical mass to make it to the next stage..

A sample question could be:

When installing a BSS Soundweb in a rack, can they be stacked with no spacing? Has anyone every had heat related problems?

Or, another sample question could be:

What is a good resource for figuring out how to send wake-on-lan to various computers from an AMX controller?

A BAD question could be:

What does the blinking red light on an AMX frame mean?

So, please go to:

http://area51.stackexchange.com/proposals/8341/audio-video-control-systems

log in and post sample questions..

thanks

I recently attended infocomm 2010. One topic of discussion was “Green AV”. It was pretty prevalent. Some manufacturers had amp meters attached to their gear with digital readouts so you could see in real time the amount of power consumption. I’ve even been noticing LEED accreditations on the email signatures of AV professionals.

Really? Green AV?

For years we’ve been integrating wake-on-lan, and sleep-on-lan procedures in our AV systems to minimize power consumption. I wonder if that qualifies us…

Green AV is a tough concept for me to get because i feel the best thing to do often is “turn the damn thing off”. Though I suppose that would be against my interest as one who makes his living from designing AV systems.

On nearly every project, I work up heat/power loads to determine how much electricity we’ll need as well as how much air conditioning required to cool the system. A few years ago out of curiosity I started to convert the power loads to their equivalent in oil (it was easy to find the conversion, though in the US I suppose most system are ultimately powered by coal).

There are about 5,800,000 BTU’s in a single barrel of oil. A barrel of oil is 42 gallons. Assuming perfect efficiency in the generation process….. You can take a 50” plasma screen and estimates that it consumes about 500 watts and further assume in a typical system runs for 12 hours per day. Total consumption for the day is 6 kilowatt hours. Multiply that by 3.412 to get the BTU equivalent, and we find that running this screen for the day consumes .353 barrels/oil.

Say your digital signage network has 20 screens, and you run them 12 hours per day, 365 days a year. The consumption is about 26 barrels or 1092 gallons of oil, not counting the computers to run it and the air conditioning to cool it.

I wonder how often the message is worth it? What exactly is Green AV?

–olaaf

An updated PrePix version 0.3.3 is available for download. This is a minor update that fixes a problem affecting Windows XP users who were unable to run version 0.3.2.

The new version may be installed directly over any previous version. Please let us know if you have any trouble!