SmartMediaCenter - PROJECT IDEA UNDER DEVELOPMENT
A mobile client-server architecture for controlling your home cinema
The typical use case
Imagine you're in the office, on your way home, shopping downtown, or wherever you are at the moment, except: Home. But you've got a webapp on your mobile device, that allows you to select what you want to be watching in your home cinema, once you get home. You just select one of those so-called Virtual Channels from a list in that app, and continue what you're doing.
But once you enter your home later that day, you'll already be hearing some music coming from your living room. And entering your living room, you'll find that your projector, which is connected to your PC, has been magically switched on. It projects some internet video stream onto your wall, showing some amazing panoramic views of the Swiss Alps. But its sound is on mute, while you're hearing Haydn's Emperor Quartett from your hard disk instead. You're hearing that through your Sourround Sound Speakers, which are also connected to your PC.
And all this has been going on since only a few minutes before you arrived home. Before that, your PC and your projector have been both still on standby, playing no music, no video, nothing, just silence. This sudden video show probably woke up your dog, completely confused why all this is happening without anybody home. You're probably surprised by all this yourself, since you've completely forgotten that this is going to happen. Because, it's not like you had to hit some other button entering home, saying "start playing now" or something.
And the funny thing is: Should your friend ask you to come over due to some sudden emergency right now, you can just leave. No need to switch off anything. Because while you're waiting on the next traffic light on the way to your friend, everything at home has already been shut down by itself, so your dog can continue to sleep.
So surprise, surprise? Well, not really. Because what makes this all possible is your entire system called SmartMediaCenter with all its hardware and software components. But let's tell the story right from start...
Hardware setup
You have an environment with the following hardware equipment:
- Ideally, a low-energy single-board computer like a Raspberry Pi. Or otherwise: Just a computer that can act as a server. Let's call it the Service Host. It is permanently on-line and accessible from the internet through proper NAT-settings on your home network's router. Make sure your router itself is accessible through a static IP address. Alternatively, you can set it up to use a Dynamic DNS server. Find some free ones here, here or here. The Service Host needs to be able to wake up the following host:
- Any personal Desktop computer of any OS that runs a Java Virtual Machine (JVM) installed on it. This desktop is called the Player Host and must be able to be woken up in some form by the Service Host. Typically, that's via Wake-on-LAN or some similar technology. So to make things easy, the Player Host must be connected with the Sevice Host via an Ethernet LAN wire and adapter. The Player Host must also have internet access and be able to play back audio and video multimedia content on its hardware. For reasons still to uncover, it should also have a Bluetooth Low Energy (BLE) device (USB-dongle or internal) permanently activated. It is further extended by the following output periphery permanently connected to it:
- Speakers
- Headphones (optional)
- A projector (very important!). What would a proper home cinema be without a projector? Right. Just any projector that serves your standards will do. As long as it can be connected to the Player Host's graphics card to display its output, whether via VGA, DMI, HDMI, DP or whatever. But most importantly: It must be possible for the projector to be switched on and off by the Player Host, so there has to be some sort of control connection between Player Host and projector! It might be hard to imagine how. This could be possible, if the projector, too, has an Ethernet LAN port and supports Wake-on-LAN, just like the Player Host. But this already forces the Player Host to have at least two Ethernet LAN ports (remember, one already taken for connecting to the Service Host). Also, Ethernet-enabled projectors are not that common, not to talk of them supporting Wake-on-LAN. Anyway, modern marvels have made it possible to gap bridges like these. Which brings us to the final equipment:
- A Naran MicroBot Push. This miracle worker serves as a robotic finger that can push buttons anywhere you place it. It can be controlled via a Bluetooth Low Energy device. That's why the Player Host should have a BLE device, while the MicroBot Push gets placed right on top of your projectors on-button. The Player Host will switch the projector on or off all by itself, when needed!
- A mobile device with any OS of your choice. Just needs to have mobile internet and a modern web-browser installed. Of course, it's your router's DNS address you're going to type into the browser. And very important: The mobile device must have its GPS activated permanently.
Key ideas: Virtual Channels and location-based playback
The playback of content by the SmartMediaCenter Player is organized around the concept of Virtual Channels, with Media Resource configurations at their base. Think of the following situation:
You know a lot of beautiful video streams that offer great visual content, such as panoramic landscape recordings or downtown tours of amazing cities, old and modern on Youtube, or even a broadcast on your local public television channel webstream that may show a live football match. But typically, you completely dislike the corny background music in it, or the lack of any at all, or the boring German football commentary. You want to replace the audio part with something classier for those landscapes or old cities, some exciting talk radio show for those skyscraper views, or just some fan music for the football match. Or, if the classy music for the medieval city isn't enough, maybe you might want to add in some great audio lecture about its history as well. But in an appropriate volume, so it's not completely swallowed by the music.
In any case, you want to replace the useless audio in the video with something much more appropriate to the visual content, in your view, and pretend like it's really part of the video. One way to do this is, of course, manually: Mute the audio in the video resource and dig out and open what you want to hear in separate audio player instances running in parallel. Even more time consuming, you could use some video studio software to create new video files that include the audio you want in it. But all of that can become very irritating at some point, having to recollect, fine-tune and start what goes together every time for hundreds of such audio-video playback combinations. Switching the combination spontaneously several times a day? Even more irritating. And you will not be doing that as frequently and spontaneously as you would like to.
The alternative is, to have a software manage all that. One that allows you to simply select and play a ready-made setup like this, we'll call it a Virtual Channel, from a list. So the heart of the configuration of that software, is simply in editing the lists of so-called Media Resources (audio and video) and their combinations, playback volumes and playback devices (speaker or headphone, screen or projector) in such Virtual Channel configurations. Those can then be launched and switched over and over again through a graphical user interface on a smartphone, just like zapping through the channel list on television. Even better, if your current geographic location according to your phone's GPS determines wether playback should be started or stopped right now.
All these features are realized by SmartMediaCenter, which includes the following software components:
Software components
SmartMediaCenter Player
The player component of SmartMediaCenter. Accessed through RMI by the SMC Service. Hosted on its own host that is woken up or set asleep by the SMC Service host, as required.
SmartMediaCenter Service
The service component of SmartMediaCenter, providing a GWT-RPC-based access service for mobile web clients to the SMC through Servlets on a Tomcat webserver serving compiled JavaScript web pages as a GUI. The component is meant to be hosted on a permanently accessible host with very low energy consumption, like as Raspberry Pi. Besides providing the mentioned service to a mobile web-client, this component controls the current playback configuration and the state of media playback on the SMC Player component host via RMI. For this purpose, it also wakes up or sets asleep the SMC Player host, as required.
Developer hints
SmartMediaCenter is really currently being developed, still working on a first prototype to be uploaded in due time!
- Everything will be completely Maven-ized for development (dependencies, plugins).
- Everything will be as cross-platform as possible by using Java wherever possible.
- Installation/setup on the target host will be made as simple as possible by using a JAR-based Maven-call even for that. So package will ship with Maven included. Will try to get all separate components on Maven Central, in order to realize an online-installation package.
- Will utilize VLC player for playback of media resources (launching multiple instances). VLC will ship with the package, if possible, installed on target host by Maven through dependency.
- Fully preconfigured Tomcat, including user access control and certificate for the SMC Service. Certificate to be generated during setup on target host. Just run the Maven-based setup.jar.
- No OS service (for Tomcat or SMC Player) installed by the setup.jar. Can be done manually, if desired. But just running the main launch JAR after installation will suffice.