This is one of my coding projects. I'm fairly new to linux, so I need some pointers and thoughts from you guys, before I get started. I know there exists screen sharing software already, but I want to make my own! (=
Specifically, I want to clone my laptop screen to my TV over WLAN, via a linux box that is connected to a TV through a VGA cable:
Laptop streams it's screen
Linux box reads the stream
Linux box outputs the stream into the TV (through a VGA cable)
First of all, how do I record the screen and send the stream in real time in linux?
Secondly I must write a program that reads the stream being sent. The program must listen to some port, and collect the data being streamed from the laptop. Any thoughts?
Then I must output that data in real time to the TV. Do you how any ideas on how to solve this?
Thanks!
Edit: Regarding programming languages, I'm most comfortable with python.
Sharing your screen can be done via the various flavors of VNC (ie. RealVNC, TightVNC, UltraVNC, etc.). Most of them are Open Source, you might want to:
Stick with the VNC protocol for later compatibility
Take example of how the established solutions does for screen-hooking.
In Linux, the graphics are all processed by Xorg (new version of X Server), which was developed with networking embedded. This explains why you can ssh -X into a machine, execute a graphical interface on it and see it on your remote computer. I recommend you to read about hooks on Xorg to achieve your needs.
You need a client-server topology to achieve your needs. You are not talking about any programming language you forecast to use, though. Some languages may be harder than some to start with. Furthermore, this kind of code is already really well understood under every major programming language. You should try to at least use a framework that simplifies your networking portion of the project.
Sharing a screen on the TV can be done by your video card driver in Linux. Just check on your Desktop Environment (KDE and Gnome offers video configuration panels, for example) or in your video card configuration (nVidia and ATI Linux drivers offers multiple screen support)
It seems to me like you're trying to reinvent the wheel and are not too sure about how to begin. I recommend you to begin simple with one of the already proven VNC software and see how it goes from there. If a feature is missing, you've got the source code of the server and the client, so you can continue development of these projects. Once you've got your setup working, start thinking about replacing a single piece of the puzzle by your own code, and see how it goes.
Do not expect good (full HD, for instance) video quality on your TV without some very capable CPU/GPU and a 802.11n wireless network empty of users and be ready to accept some lag for the codecs to kick in.
You should try to take as small steps as possible. If I were taking up such a project, my first step would be to try to implement a solution using standard unix tools (e.g. netcat or socat for the network part, mplayer or vlc for the playback and maybe ffmpeg for the capture)? Then, replace each component with custom-written ones if needed.
Related
So in linux there are all kinds of menus and application launchers, but no one of them suits my needs.
Please, let me explain you what I want to do.
I student in a school now so we have fancy dreams and all those never getting involved ideas, but luckily I try to realize some of them.
I want to build an open source gaming platform, a video game console with a linux distro that is based on debian stable liquorix kernel and all that kind of stuff, but it needs its custom DE and something different from the PC interface as it will be controlled by a gamepad and will be a video game console, people must think it is not like a PC, people must see the cool interface and kind of realize that it is different.
The problem is:
All applications menus from other Desktop environments are a bit too windows-like which does not provide a video game console experience.
What do I need for that? How can I read a source code from other applications menus? How can I make something rounded in xorg, as I want to make it a cs:go-like rounded menu (CS GO is just for a reference, I don't play that!)?
I want to make a system which would get input from USB barcode scanner, validate it on remote server and display an answer (text and images).
I would use JavaFX or in-browser JS web application to grab scanner input somehow.
I'm planning to run this application on Raspberry Pi or plain PC.
Is there a way (or a special linux distribution) to ensure that system always loads the same way and starts JavaFX app or opens particular web page in browser?
e.g. no login page, NO update or other popups are shown.
Any other ideas? Thanks
...
Found an interesting solution here, where JavaFX GUI app is started from command line, without X-Server(linux graphical interface) at all.
I have recently done something similar, and it's not too hard. Obviously working on the Pi, you will want to use something like Linux and having limited hardware will mean that you should be minimising what you are running. Due to this, I would recomend that you run a light weight distro. Something like arch (which is what I used) allows you to build only what you want from the ground up without the need to find and compile everything like you do for LFS or Gentoo.
As for booting, the following two wikis will give you the details of starting the Gui without manual login:
https://wiki.archlinux.org/index.php/Automatic_login_to_virtual_console
https://wiki.archlinux.org/index.php/Start_X_at_Login
After that, it is simply a matter of putting the command to launch your program in .xinitrc.
I'm just i a planning phase of an app i might possibly make, and I came across a challenge. In order to accomplish my goal it seams to me that my program will need to act as a microphone and a speaker to the OS. I'm considering to make my program for both Windows and OS X, so my question is as follows:
What libraries do i need in the two operating systems to make them think my program is an audio device? I need to be able to both emulate audio input and output. On Windows i have a feeling that it might be DirectX or something, whereas on OS X i have no clue.
Also if such a library exists, and you have one to suggest, please also suggest a source of documentation. =)
Thanks in advance.
You make your program an actual device and write a device driver for it.
For device driver development on Windows start at http://msdn.microsoft.com/en-us/library/windows/hardware/gg487428.aspx
For device driver development on Os X start at https://developer.apple.com/library/mac/navigation/index.html#section=Topics&topic=Drivers%2C%20Kernel%2C%20%26amp%3B%20Hardware
So, I know Linux kernel is quite "heavy" when considering lower scale embedded systems, but currently but we're a 2 man team trying to see how to create our own embedded system.
I'm the one in charge of all software (the other guy is a HW guy), and thus I would like to re-use existing libraries and frameworks as much as possible, and I would like to bounce off some ideas with gurus around here.
I am fairly comfortable in Linux, but the booting and initialization process is new to me, and I need to dive in to that soon enough. Any book recommendations are welcome as well!
I haven't designed any embedded systems before.. Only own some ARM dev boards (beagleboard and raspberry pi).
Current I have prototype of the software running on beagleboard already, and now we're thinking how to minimize the cost, and to create something our own..
It's a system connected to the internet, and I need to run a tiny web server with some scripting support. Performance wise I don't think it needs to be too powerful.
I would like to minimize all bootloader etc work, since I'm a one man SW team, and just concentrate on the application itself.
Of course I understand that I need to configure our kernel for this, but this is indeed why I thought selecting some SoC would be good, since they usually have some linux and bootloaders ready..
First I thought that Cirrus EP9301 would be perfect, since it seems to be a good package, and not very expensive.. But it seems that it's already in end-of-life, and also support for this is very bad (people on the cirrus forums constantly complain about it).
Are there some good choices for this kind of project, which would enable us "easily" to get linux kernel up and running, with still maintaining some kind of decent BOM (hopefully 20USD or so) ?
Your hardware guy should already know this, but go with an existing reference design. Take the raspberry pi, the beagleboard/bone, open-rd, or any number of other existing systems and clone the part you need. As a result the linux porting will be a matter of removing what you are not using from the reference design instead of adding new stuff and hoping it works. If you go with flat pack parts you can do the work in your garage, if you go with bgas you need the equipment for that or pay someone to do it. (can you tell yet that I hate bgas?).
Is linux a requirement, if not that opens the door to a lot more devices using freertos or chibios or a number of other solutions. the stm32f4 discovery board for example is $20, uses what can barely be called a microcontroller for all the features it has (cortex-m4). Supposedly possible to run uclinux on a cortex-m, but definitely possible to run any number of rtoses and have an ip stack, etc. stellaris (ti.com) has a number of eval boards, one/some with ethernet already (use as a reference design). You can also take the wiznet approach (or a spi ethernet) and use any microcontroller (puts you into the avr/msp430 level and price range). Bang for buck the cortex-m's are good, arm based so comfortable to work with, etc.
Using linux if you are already not an experienced at porting to an embedded platform, and dont want to learn that on this go around, I would definitely go with a clone of an existing design, leverage as much as you can from a project with folks that are experienced at porting linux to a platform. If need be take an existing board (beagle/raspi/openrd) and go through the motions of porting to the platform with the cheat sheet of having access to an existing port, see if you cant get uboot ported and linux booting, etc. (dont really need uboot at all, that is possibly an unnecessary complication, just get dram up and pass the atags, etc to linux and just branch to it, pretty easy to launch linux from bare metal).
You could probably do worse than taking the Broadcom BCM2835 - used on the Raspberry Pi - as your starting point - especially if you want to avoid kernel and boot-loader work and a source of reference schematics. If this proves too expensive, check out other devices in the Broadcom range.
A few bits of advice
You probably want some flash rather than a MMC card interface for production use. eMMC is an option. NAND flash is a nightmare due to rapid component obsolescence and the need to get own and dirty with the MTD drivers.
USB Ethernet will be easier to integrate than a controller hanging off a general purpose bus, but won't perform as well. SmSC seems to be popular source for either
You could also have a look at the work that Olimex is doing with their linux boards. Perhaps even order a som and then combine it with other external components.
I'm looking for a really really small linux distribution or process of making my own that's sole purpose is to get an air application to launch full screen and stay there; Essentially I'm building a home kitchen computer that runs entirely as an AIR app.
I have looked into using windows xp; and windows xp embedded but they pose so many issues I figured I'd try modern linux.
I have also seen TinyCore Linux which looks interestingly small but not sure what issues that poses in regards to running AIR and "hardware" accelerated display. I've also thought about stripping down an Ubuntu installation but I'm sure somebody must have done this already; google is just failing me right now...
I'm also interested in running an "embedded" version of say android and running the air app on some arm-based hardware again; with just the AIR runtimes only - although this is less preferred as it's more complex.
I'm also hooking this up to a touch screen monitor (not yet arrived) so I'll need to hunt down or write some drivers for translating the touch events into something AIR can understand... (this was my main intention for using windows in that all the drivers will just work).
What I'm after
Minified Linux kernel with JUST the drivers for the box I need
X Display with accelerated graphics support (Doesn't have to be X if AIR can run on a frame buffer?)
Running a Full screen AIR application (simple enough)
Ability to write back to the filesystem (enough support for AIR)
SSH Access for remote control
Samba for updating the filesystem (easier to maintain the system)
Touch screen support (3M Ex III I think...)
Audio support
Don't need
Don't need any window manager or any other GUI tools unless required by AIR
Don't need any toolbars or file managers or anything; The AIR app is the "OS"
Don't need any package managers or repos
Don't need multi user or logging in; everything can just run as an unprivileged account
Don't need to
I don't mind hand crafting the filesystem and configs if that makes it easier; I'm mainly looking for a "filesystem" that is as tiny as possible that I can just plop my AIR app into and write some scripts to get it to start when the X server starts
Thanks,
Chris
Try an embedded Linux build system such as Buildroot. It can build an entire system from source, and be very lightweight. The basic system is less than 1 MB in size.
Ended up going with Tiny Core. Very tiny and quick to boot up. You can also write extensions for it and you don't have a persistent drive which allows you to just switch the thing off without worry that it's going to break something -- exactly what you need in a kitchen :-D.
My current plan is to:
Just set up a working version using Ubuntu as this is mostly supported by Adobe
Slowly strip it back and try and get as little things to start as possible on boot
Try building my own distro/package from source and selecting only the packages I need
Compile my own kernel with nearly everything turned off and just leave on the things I need