I am posting this to know whether a media player can be developed with Qt5 without using gstreamer plugins as backend.Is there any other backend engine available in embedded linux platform to play media files other than gstreamer. I am using intel X86 32 bit architecture.
Thanks in advance.
Just checked the Qt5 plugin sources (/qt5/qtmultimedia/src/plugins) and it seems like gstreamer is the only option for linux. Phonon has been dropped in Qt5.
If you want to use phonon you'll have to stick with Qt 4.8.
Qt5 on Linux only supports gstreamer by using the plugins in http://qt.gitorious.org/qt/qtmultimedia/trees/stable/src/plugins. Of course you can write your own plugin using ffmpeg or whatever you want. This is pretty simple, but entirely depends in the performance you need.
Phonon was available in Qt 4, but AFAIK Phonon is gstreamer based again. There is also a project to create a vlc-based Phonon, but I don't really know how it works (https://projects.kde.org/projects/kdesupport/phonon).
However, you don't specify your specific target, but if you want to achieve acceptable performance for graphics and/or video on embedded devices, you probably really need hardware acceleration. And Phonon will hardly help you with this. Also consider that Qt 4 is old: it misses years of development.
I'm also writing a Qt5 backend using OpenMAX and ffmpeg: http://thebugfreeblog.blogspot.it/2013/04/hardware-accelerated-qtmultimedia.html. It might be an example if you need to write your own.
Also consider that the errors you reported (why reporting in an answert?) seem to suggest you built gstreamer wrong.
I am currently looking at using PySide for mobile app development. I've done a few tutorials for creating desktop applications using Pyside and loving it. I understand PySide/PyQt is a port or mapping for Qt, and is usualy behind a little bit with Qt as developers of PySide/PyQt have to keep up with whatever happens in Qt.
I particularly want to develop for Android, BlackBerry and iOS. I also understand that Qt recently added support for Windows 8, as well as the more recent BlackBerry 10 OS.
My question: How well versed is PySide/PyQt in its current state with cross mobile application development.
Does it achieve mobile development by means of the WebKit component, allowing the use of everyday HTML, CSS and JavaScript?
Would it be a better option to consider PyQt for mobile app development, or PySide?
I think its not realistic to think you can use PySide/PyQt and Python in order to make one application suitable for all those platforms.
First of all the platform you want to develop for should support your programming language (Python) as well as the graphical framework (Qt) in order to make it work. This is mostly achieved by third party developers. If Python runs on your mobile operating system this does not say you can start developing and vice versa.
Mobile development is often done with QML (Qt Modeling Language). This allows you to make really cool and fancy interfaces on many platforms. You can connect it to your own Python code to make a real working application.
At this moment Qt is working on support for mobile devices. Most mobile operating systems like iOS and Windows Phone are not supported yet for the combination Python/Qt and mostly the support for working projects is not really big in comparison to the preferred languages of the operating systems.
Here is a list of mobile OS's which support the combination Python/Qt
Link to projects if there is a good link for a starting points is available
Android: PySide for Android
or if you like to use "webviews" instead of PySide: SL4A
Blackberry 10: BB-py
Meego: Python/Harmattan Project
SailFish OS: Harmattan apps (Meego) run without any problem
For your other questions I have a shorter answer.
The webkit component is intended as a content viewer component. Its not a component for building full HTML 5 apps.
The question which bindings for Qt are better is often asked. What you need to be aware of is that the old version of PyQt did almost the same as PySide. The difference was mainly in the license! However PyQt supports now Qt 5 while PySide doesn't, so make your own choice. I think you can make beautiful apps with both of them.
We are trying to develop a real-time display system in safety critical domain. (All this is at very basic stage.) One option I have is to write my own Widgets using OpenGL. Other two options is to use something like GTK or QT.
QT seems easy to use and has good development tools. But I have worked on several applications in real-time domain using GTK but none in QT.
Can anyone point out to me the trade-offs involved here ?
I am settling with direct OpenGL programming for now.
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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
I have started using Python for web development recently, it's kinda cool;
I have seen programs that are developed in QT/C++, which is good enough in terms of esthetics;
I have just noticed the new PySide project (which brings LGPL Qt license to Python and it doesn't support Windows yet).
In view of the above, I see the possibility of using Python + PyQt/PySide to develop cross platform apps in the future :) but I have several doubts right now:
Can PyQty/PySide be used to develop really complex/modern UI? Can somebody give me some points to have a look at some nice-looking screenshots of apps that are developed in Python+QT?
What about the performance of using Python + QT for a desktop app?
Thanks in advance!
Can PyQty/PySide be used to develop really complex/modern UI?
Desktop applications come in all sorts of varieties -- some nicely laid out, some extremely customized with virtually no semblance to a standard application for that OS. The same can be done with Qt/PyQt/PySide. As Alex said, there should be no visible difference between an application written with PyQt/PySide versus one written with Qt in C++. Any program written with Qt4 (using bindings or not) will, by default, look like a standard modern application.
Of course, there are features of recent Windows releases (and likely some on Mac OS X) that aren't supported immediately and by default in Qt, but you can almost always write some custom platform specific code for those situations where said features are truly important.
Can somebody give me some points to have a look at some nice-looking screenshots of apps that are developed in Python+QT?
The best and most open source program that I know of and which is written with PyQt, is Eric -- a Python based IDE.
What about the performance of using Python + QT for a desktop app?
For most applications the performance difference between a C++ Qt application and a PyQt application are not noticible. But if you really need performance, you can write certain parts of the application in C++ and make bindings available in Python so you can integrate the two.
TortoiseHg was re-designed using Qt and PyQt for its 2.0 release.
Here is one of several posted screenshots:
There is no aesthetic difference between the look and feel of C++ based Qt, and the PyQt and PySide wrappers on top of it. I use basically no desktop GUI apps so I couldn't point you to any implemented with any of these language/toolkit combos, but if you like the former, you'll be hard put to distinguish it in any way from the latter.
A bit late but for the record, apps such as Skype, GoogleEarth or the recent versions of VLC (media player & more) used the Qt libs.