I asked this question in the Raspberry PI section, so please forgive me for posting this here again. Its just there doesn't seem to be as active as this section of the forum. So, onto my question...
I have an idea and I'm working on it right now. I just wanted to see what the community's thought was on using a screensaver as digital signage. Every tutorial I've read shows someone using chromium in kiosk mode, and while that's fine and works well for some uses, it doesn't work for what I need. I have successfully completed a chromium kiosk, and it was cool. But the signage that I need to create now, has to work without internet. I've thought about installing LAMP locally on the PI, and still using chromium. I still may have to if this idea doesn't pan out. All I need from the signage is a Title Message in the top center, and a message body underneath it, with roughly 300-400 character limit. My idea is to write a screensaver module, in C, that will work with a screensaver such as xscreensaver. The module would need to be able to load messages from a directory on the pi. Then for my clients to update their signage text, I would write a simple client that sent commands as well as the text via SSH to the pi. I want to know what other people think about this. Is it a good idea? Bad idea? Should I "waste" my time doing something like this?
Thanks in advance.
I am already using a rPi as digital signage, just over a year. I am using two different setups:
version 1 uses Raspian loading xdesktop and qiv image viewer to cycle images stored on the Pi itself, synchronized with a remote server. The problem I found was power and SD stability, when the power fails, which it will do no matter what, just when... The Sd card can become corrupt due to all the writing that Raspian does all the time. Certainly does not really need to write to SD.
version 2 uses a RO-filesystem and a command line image tool. Uses the same process to show images from local, and sync with server. But power fail causes no ill effects.
I am not using screensaver to display images, that seemed redundant to me, and unnecessary to wait for the SS to start just to display the images.
Some of the images are created using imagemagik, which is nicely dynamic where needed.
Related
This is a very simple task that I had such a hard time trying to do. My goal is pretty simple: send an mp4 file from my server to my client, and while its buffering and downloading I want to already play it. That means that I need to play a video.mp4 file while writing it, and I need it to display on some platform that I can control - like wxPython or WPF-Ironpython. Naturally, no such platform will let me play an open file for writing.
I have tried to implement and HTTP server (although totally unnecessary for my case, as I am writing an application-based Server-Client app) that would accept Range request, and when I run the server and load the URL on Chrome, it all works perfect and I can seek and buffering is great, but when I load it from WPF MediaElement it fails to play the video for some point (I cant really tell why as there is no documentation for this, any API, tutorials etc). I am really desperate.
I even thought about playing a video from a buffer and then just changing the buffer's content, but it doesn't seem like this possibility exists.
I am really stuck at this and I would love to get some suggestions. Please note that I am not a professional in this so I would appreciate if you could explain this to me in simple terms.
Thanks!
Not possible. MP4 is not the correct container for your application. You must use something like HLS/dash/fragmented MP4.
I am very new at this and trying to get an understanding of this. I have read a lot on the DroneKit-Python site trying to figure out how exactly am I able to communicate with it.
Drone I am currently using is Iris+
I have looked more and there are software that already provide this, but I want to be able to control it plus more.
I want to set waypoints, tell it to then fly give the way points and keep going to them. Also, to be able to arm itself, which is in the example, and override the safety mechanism.
Here is the basic of what I am trying to use it for. Have it fly up at a certain time. Go to the waypoints 1,2,3,1,etc.. Then after X amount of time or on low battery go back to launch point and land.
I have found plenty of code that provides what i need to do, though I don't know if it will work and more importantly I don't even know how to start programming for this. Maybe I have the wrong approach in doing this?
I kind of want this to be a light API, so that in the future I can make a simple UI on my phone and insert some coordinates to give it ways points and that is it. I know there is software out there already that does it, but I want to remove the need for touching the drone. I want it to start and end autonomously.
If anyone could help provide some info that much would be greatly appreciated.
Assuming you have no companion computer (Iris+ does not by default), you are OK with running a ground station app (you won't be out of range to send commands to "end mission on time expiry") and that driving the behaviour from your phone is important, I would be looking at DroneKit Android.
Some notes:
You're going to have to touch the drone at some point to attach the
batteries.
You can arm the device from dronekit
You can override the safety mechanism from a script. I hope you have
a lot of money to pay for the new drones you're going to have to buy when they crash and all the litigation from damaged people and property (in other words "don't do it".
The default behaviour is to return the device to launch (RTL) on low battery. This is convigurable
Setting a time is more "problematic". You can have a timer in a script that then sends return-to-launch but the script needs to be connected to the UAV. This means that either you have to be running in a connected ground station (which might potentially be out of range) or on a companion computer.
Iris+ does not have a companion computer. You have to install one or connect from a Ground Control Station.
DroneKit-Python runs on Linux, MacOSX or Windows. You can't just run it on an ordinary phone, though you could find some other mechanism to send messages/scripts to it running on a companion Computer.
DroneKit Android runs on Android. We do have a planned iOS version too. In theory these could run on a companion computer, but in practice currently these are only used as ground stations.
I would like to make a Graphical interface for a home-made program using SFML on Raspberry Pi2. I am using Raspbian. I recompiled the graphical lib
It works fine unsing startx first, then using my application, which wors perfectly fine.
But I can't figure if it is possible or how to launch my application directly after boot without launching startx (just to optimise the cpu of the Raspberry).
Starting my program direcly after boot, I get the following error:
Failed to open X11 display: make sure the DISPLAY environnement variable is set correctly.
Aborted.
I already tested the classic export DISPLAY=:0.0 but without sucess.
I interested myself in x and xinit, but I am not sure that would even do it.
Where should I start looking? I don't need a complete solution, even a hint or an idea would be nice!
I checked to see if it was possible to open a graphical app without the X desktop environment and as that answer states, with Firefox at least, you need the X server which SFML also probably needs in order to create a window.
The answer states:
Basically something like:
$ X
Then you just start Firefox in this X server:
$ DISPLAY=:0 firefox
You can switch from the X server and the framebuffer by using
CTRL+ALT+F1 and CTRL+ALT+F7.
You could try that and see if it helps.
Also, still searching, I found a forum post on the sfml website about what you're trying to accomplish stating somewhere:
SFML requires OpenGL, so as far as I know you need at least X running,
but you probably don't need gnome, KDE or a similar Desktop
Environment on top.
The forum guy asking for help seems to have managed to get X11 and a SFML basic render window to work on Ubuntu server after someone posted a link to xinitrc. I guess, that's the route to go from here.
I've been working on this problem on and off for about a month. I don't expect anybody to be able to give me a definitive answer. I'm just completely out of ideas at this point and could use anything.
The problem is that my app crashes on only some models of phones. I have an HTC surround and it runs fine. It has also been tested on a Samsung Focus and it works there to. It crashes pretty consistently on a HTC mozart. There are other phones it crashes on but I don't know what models they are. I don't have access to an HTC mozart so debugging has been very difficult.
I'm handling the application UnhandledException event and I have try catch around every background thread. The error handling code never runs.
What I know:
Sometimes it freezes and requires a press of the power button. At least once it required the battery taken out. Most of the time it freezes and then crashes.
Most of the time it crashes on the main menu, before everything displays.
It's not 100% consistent. Sometimes it works for a little bit, but never very long.
It's not because it's out of memory. Most of the time it crashes while using less then 8MB.
When all the exception handling didn't work I added debug logging. This slows things way down but at the same time the issue goes away.
These symptoms make it sound like a deadlock to me. Although I have gone over the code and there is no thread ever entering more then 1 lock at a time.
Any ideas on how I should track this down would be appreciated.
Edit: This is a WP7 version of my game. I've just been able to confirm with a volunteer with an HTC mozart that the simplest conversion of the code meant for to run on the web will crash on the phone. That's code has no networking, isolated storage, or sound.
I also should have mentioned that this has passed certification and was in the marketplace for a few days until I took it down because it got bad reviews (because it was unplayable for some people)
If the devices are locking up, then my suspicions would be to look at the areas where you are closest to the driver level/hardware, which (looking at your game) are:
the display
the sound
It could also be just about due to processing/CPU activity - but generally "User level" code shouldn't be able to lock up your phone - that functionality is reserved for kernel software.
The only way of really testing this is to get hold of a device where this "reliably crashes" (e.g. a Mozart) and to go through the process of disabling bits of functionality one by one.
If this is a Silverlight app, then I'd expect Microsoft to want to help - I'd contact them via AppHub and via their local Evangelist team - they'll have the means and the motivation to assist you.
I'm happy to assist on testing on a developer-unlocked HTC Trophy if that helps!
The only thing I can think of that's unique to the Mozart is that it has an 8MP camera and all others have a 5MP camera.
Are you using a CameraCaptureTask and expecting the returned image to be a certain size?
Other than that, what does the app do? what services and device functionality are you using?
Do you have any network access running on a background thread?
I had roughly the same problem when developing my WP7 app. As far as I can tell it isn't as much model bound as it is device bound. In fact I had my app deployed to 15+ Trophy's (my company gave all their employees one of those) and it would repeatedly crash on some of them all having the same firmware. Some of the feedback I got through the reviews seems to indicate that it also happens in the wild.
In my case the crash occurs primarily (only?) when the app is launched. There does seem to be a strong correlation between internet connectivity and crashing in that I can 'recreate' the crash by putting my phone in flight mode, unplugging the network cable from my computer and then deploying the app. In that case too it immediately crashes and no event or break point is ever raised.
My gut feeling tell me it might have something to do with the map control as that does tend to respond funky to poor connectivity when the application is loading (like displaying an error message that the card cant be loaded while simultaneously displaying the map)
Does your app also use the Map Control (in combination with a Pivot control perhaps?)
Some of the devices have issues where you need set things to "content" instead of "embedded resource" in your project.
Although i've more heard about that issue related to app startup time, as on some devices (HD7?) the load of the app was taking enough time that the app was never allowed to start, the OS thought it was taking too long and killed it.
I want to make project for my final year in college.
So someone suggested me to make Remote Desktop in C.
Now I know basic socket functions for windows in C i.e. I know how to make
echo server in C.
But I don't know what to do next. I searched on internet but couldn't find
something informative.
Could someone suggest me how to approach from this point..any tutorial...or any source ?
I think this is do-able. For a college project, you don't need to have something as complex and as full-featured as VNC. Even demonstrating simple keyboard and mouse control and screen feedback would be enough, in my opinion, and that's well within reach.
If you're doing everything from scratch and using Win32, you can get the remote screen using the regular "printscreen" example all around the internet.
http://www.codeproject.com/KB/cpp/Screen_Capture__Win32_.aspx has it, for one. You can then compress the image with a third-party library, or just send it raw; this wouldn't be very efficient but it would still be a viable demonstration.
Apart from capturing the screen data remotely and showing it in the local window, you'll need to listen for local window messages for mouse and keyboard events, send them to the remote host, and then play them back. http://msdn.microsoft.com/en-us/library/ms646310%28VS.85%29.aspx will probably do that for you.
Check tightvnc TightVNC is a free remote control software package. The source code is also available.
For sending the image of the screen I would probably use rtp. The JRTPLIB is really handy for that.
And yes, as KevinDTimm says, an echo server is the very easiest part.
KevinDTimm may well be right, writing an RDP client would a fairly significant undertaking. To give you some idea, the current spec, available at the top of this page, is 419 pages long and includes references to several additional documents for specific aspects of RDP like Audio Redirection and Clipboards.