I was trying to use Qt for playing live video for which Qt provides a phonon class. However, the limitation with this is that it is not capable of decoding RTSP packets on windows (since phonon uses Directshow on windows platform).
In order to make it capable of doing this, I am planning to now integrate openRTSP with Qt. Within openRTSP where can I find a pointer / handle to the video buffer or frame buffer so that I can pass on this to my Qt widget for display.
Has anyone attempted this before?
Any pointers on the correct approach for doing this would be highly appreciated.
Take a look at GStreamer and GStreamer Qt bindings. They provide VideoWidget etc so it should provide you enough code examples how you should do this: http://gstreamer.freedesktop.org/modules/qt-gstreamer.html
Right now I am in no where :( I want to develop a video player where human will be detected using a detection algorithm which is already working in visual studio platform. My player should simply show the detection in video player. I want use QT framework for that. But the problem is I am not sure which one i should go for. There is option of using Phonon, GStreamer, and vlc player that can be use for my purpose but does anybody has any real experience like this kind of stuff ??
Thanks in advance !
GStreamer is a great cross-platform multimedia framework and I've used it many times, including a few projects involving Qt. Knowing GStreamer certainly adds a great skill to your arsenal but it will take some extra time to understand it's design and how it works.
I've never used VLC Player, and Phonon should be your last resort because it is dying.
Another option you might consider is QtMultimediaKit, which is a part of Qt Mobility. It's Qt all the way and may be an easier transition to your current set of skills.
What is the difference between Qt for Symbian and Qt for MeeGo? I know Qt is a cross-compiling platform. Does this mean that if I use a library from Qt the exact same library works on all devices which support Qt (e.g. Symbian, MeeGo)?
For example:
QtDesktopServices can launch a web browser. Despite the name 'Desktop' is confusing for mobile devices can I launch a web browser on every device which supports Qt? If I look at MeeGo, MeeGo is used for different kind of devices e.g. In-Vehicle, TV, media phone
Is it guaranteed that every device has a web browser on it? I don't think so and that's why I'm asking. If a browser is guaranteed, which browser is it? Which features does it have? I know there is WRT, but a user here stated that WRT has discontinued. So what now?
Do I have to choose between Qt 4.7 and Qt Mobility 1.0?
What leinir said - Qt Mobility is a module that implements common features for mobile devices. Qt's API is the same on all platforms, though there are some platform-specific functions (mainly dealing with low-level stuff).
While the API (the interface) is the same, the implementation of course may be different. I suggest looking at the Qt online documentation - the pages linked under "Platform-specific Development"
According to "Platform notes - Symbian", the Symbian port is not complete and lacks some features (e.g. OpenGL support is "planned for a future release", while printing probably never will be supported). I'm pretty sure that the MeeGo/Maemo version supports OpenGL ES, as I've seen a Qt-based application using it (Stellarium on a Nokia N900).
QtMobility is an extra module for Qt, which provides a bunch of extra functionality which is more esoteric than the other 13 or so Qt modules, but functionality which is really useful when you are building applications the way you suggest.
So no, you don't choose between Qt 4.7 and QtMobility 1.0, because you have to use Qt to be able to use the extra module QtMobility :)
The browser will always be whatever is set up as the default browser on the system. So, no, there is no guarantees - for Windows, for example, you might have people using Firefox, Chrome, Internet Explorer 6 and many others. This is the nature of platform integration, i'm afraid :)
I have to develop an application which requires Bluetooth and profile change functionality for Symbian phones. After spending sometime I found that following options:
Java: but java does not allow to change profile
Symbian C++: I read basics for Symbian C++ and created some basic stuffs. Symbian extended APIs provide simple APIs for Profile and Bluetooth (I haven't tested yet). But its required lot of efforts to grab these. Specially certificate singing problem. I want to test my application on different devices and wish to give my friends whom having different cellphones. But couldn't due to signing problem.
QT: I am still confused on this. Whether this platform capable to fulfill my requirement or not. Secondly which phone supports QT or not...
Honestly, I am bit frustrated while writing this. I am looking someone, experience in these matter, to guide me in this situation.
You can combine native C++ with Qt. Though you'll lose some of the cross-platform nature of Qt by mixing native C++ with it.
See the XQProfile example on Forum Nokia Wiki for mixing Qt and native Symbian C++ for profile changing.
Qt can be installed to practically all devices from S60 3rd Edition FP1 (S60 3.1) onwards. Newer device models ship with Qt preinstalled. Forum Nokia has device specifications that you can filter based on Qt availability.
QT (+ QML) is the language of choice going forward. I believe it is currently on the following phones: N8,C7,C6,E7. i version 4.6.1 with version 4.7 which has the QML support due shortly.
However if you need to target current and older devices then your only choice is Symbian C++.
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Can someone suggest what's the best uses for those libraries today? Is it just GUI, or do they have database, XML, networking, threading, etc support too?
I was reading about them, and considered starting to learning/using one of them.
What is the most common one? What's the difference between them? Why would you choose one over the other?
As you seem to primarily target Linux, then the choice mostly depends on the programming language you want to use.
If you code in C, then obviously go for GTK+
If you code in C++, go for Qt, otherwise you will need Gtkmm (a C++ wrapper over GTK+)
If you code in Python, both GTK+ and Qt have bindings for the language: see PyGtk, PyQt and PySide (the one launched by Nokia themselves).
If you code in Java, Qt is no more a viable option imho as Nokia discontinued Qt Jambi (the Java bindings for Qt).
Also, Qt is more top-notch regarding its scenegraph QGraphicsScene API, its scripting engine built over Javascript Core (the engine powering WebKit), its state machine and animations framework, and the declarative UI.
GTK+ doesn't offer that much although you can use Clutter alongside with it.
If you're specifically looking into DB, XML (GTK+ has a parser for a subset of XML) and threading (GTK+ has GLib) features then Qt will offer all that in QtSql, QtXml and QtConcurrent.
All in all, I would say Qt is a sure choice. But GTK+ is very capable as well.
I'm not sure you will get a crystal clear answer for your question, which explains why some people keep preferring Gnome over KDE or vice-versa. Choose what works best for you.
PS: I you plan to also target Symbian, then go for Qt.
EDIT: Something that is also great with Qt is QtWebView: it brings Chromium into your Qt application to display web content. Others are embedding web content into their application using for instance Awesomium or Berkelium.
I've used GTK+, QT and wxWidgets before. Here's a brief summary:
For my first cross platform UI project I decided to go for wxWidgets mainly because at the time the license wasn't as restrictive as QT's (QT was GPL and only for Linux) and it had platform specific UI (unlike GTK). The project worked out well but there were quite a few glitches getting it to compile and run properly in other platforms - sometimes some events were fired up differently and such. Also GDI in wxWidgets was pretty slow.
Next I used GTK for a different project in python. For this I used the python bindings and everything worked out more or less smoothly. I didn't quite like the fact that the UI didn't look native on Windows and Mac and also when you launch a GTK+ app it always debug outputs loads of CRITICAL warnings which seem fine to ignore. :S
Finally, I did a very simple QT project now that Nokia has acquired it and was brilliant. The best of the three. First off, if you're not an old schooler who prefers VI or Emacs, QtCreator is brilliant. I really love VI and used it for years but I much prefer QtCreator for C++ QT projects. Regarding the library I also liked a lot the documentation and the APIs provided. QT has a concept of slots and signals which introduce new C++ keywords and a preprocessor. Basically, after reading a tutorial you'll get it easily and will start to love it. I'm now doing iPhone dev and it does feel a bit like Cocoa's/Interface Builder's UI paradigm.
Summary: I'd go for QT hands down. The license is pretty good and the SDK and documentation really nice.
I have never used GTK, but from my personal experience using Qt:
It is much more than a simple GUI. It's a whole application framework. I used to think of it as the Java libraries for C++. It provides all you mention -- database, XML, networking and threading, and more. It also provides things such as containers and iterators, and counterparts to a number of boost libraries.
The thing that impressed me most when starting to use Qt was the extremely extensive documentation. You get a program called Qt Assistant, which provides fully indexed and searchable API documentation on your desktop, as well as numerous code examples and tutorials. I found it made a big difference in searching the web each time for API info. Very quick access when you need to remember a method signature.
I am not sure which is most common; that's probably hard to measure accurately. They're certainly both popular. As Gnome is the default desktop of Ubuntu, and Gnome sits on top of GTK, it obviously has widespread usage. Of course, KDE is very popular as well. Nokia is heavily pushing Qt in the mobile space -- their Maemo OS, used on the new N900 for example, is soon to switch to Qt as the default toolkit (currently it is GTK.) I believe Qt will also soon become the default toolkit for Symbian OS.
I have not used Qt Creator, but I have heard many good things about it. It is a C++ IDE with obvious heavy integration with Qt. It also has fake vim emulation which is always nice if you like that kind of thing!
Qt uses qmake for build configuration. I found this much nicer than having to write your own makefiles. I do not know what GTK uses for building.
A couple of things I found a bit offputting with Qt at first was its big uses of preprocessor macros. The signal/slots system provides a nice mechanism for event/message passing in your application, but it does feel a bit like magic that may not be easily portable to another toolkit if you ever want to. Also, the moc (meta-object compiler), while I'm not entirely sure what it does, also feels a bit too much like magic going on behind the scenes.
All in all, though, I would recommend Qt, particularly if you are learning. It has really amazing documentation and a nice IDE, and busy forums. You'll be able to build C++ apps very rapidly with it, particularly with the QML coming in 4.7.
It probably depends on what you want to do. I would recommend Qt, because it's more than GUI, it has nice Python bindings (so does Gtk), and GUI libraries themselves are (subjectively speaking) more pleasant then Gtk.
Gtk is on the other hand more common in linux world, so you can probably get more help on the web. Reason for widespread of Gtk probably has more to do with Gnome and Ubuntu, rather then technical merits, but if you want you software to blend nicely with those two, you'll achieve that more easily with Gtk.
Qt for one sure has solid DB, network, threading support etc... It does a lot more then just cross-platform GUI (and it does most of it quite well).
I'd recommend it over GTK+.
Qt. It's not only object oriented, is "good" object oriented.
It's based on a "subset" of C++ that doesn't rely on the obscurity of C++ (but you are allowed to stick with them, if you fancy masochism ;) ).
It has a strong momentum now that Nokia bought it (actually Nokia did ~2/3 years ago). It's going to be in all Nokia AND Intel mobile devices (smartphones, netbooks, tablets).
It's the backbone of KDE, so it's very mature, but it's designed in a very flexible way, that makes it possible to support TODAY all the latest "cool stuff" that a more-then-just-GUI framework should have.
Go for it.
Just adding QT advantages to other answers.. QT has great documentation, its own IDE & GUI creator and enhances C++ with some new concepts like slots/signals (basically events).
I am not a GTK developer, so I can't compare those to the GTK world :(
It also looks like Nokia is about to use Qt everywhere, like on Maemo
If you want your app to run on iOS, Android, Blackberry, other mobile platforms, Windows, Mac OSX, and Linux, use Qt.
qt-project.org