I'm trying to make a simple videoplayer using qt. However, I can't get the videowidget example that comes with qt to work, instead I get an error: "The QMediaPlayer object does not have a valid service". I'm using windows vista. Can I get the videos to play normally, even if that example isn't working? Is there any other simple way to test playing videos? Or is this a problem with qt?
Check this VideoWidget I created: https://github.com/MaximAlien/VideoWidget. The main thing here is that the video should be in web and QMediaPlayer handles everything for you. Example works with Qt 5 and higher.
This is expected on your Vista, unfortunately. See the relevant post from the maintainer:
On Windows XP, Qt Multimedia uses DirectShow (and WMF for Windows Vista and later). The DirectShow plugin binary is not included in the Qt 5.0 package (only the WMF plugin is). You need to compile QtMultimedia yourself, or just the DirectShow plugin in qtmultimedia/src/plugins/directshow
... in the following report on the Qt issue tracker:
Qt 5.0 and QMediaPlayer failure on Windows XP
The steps to build it on your would be:
grab the tarball
unpack it
move into the qtmultimedia folder
run qmake -r
(n)make
(n)make install
Please make sure qmake is properly in your PATH before doing this.
Related
I have a project written in Qt that I have no problems compiling and running on Linux. The command line is:
qmake ../trunk/GSDTesting.pro
The process on Linux was really simple: install a few dependencies using apt and you are off.
My task is to recompile the same program on Windows using Visual Studio C++ compiler, but the problem is I don't know how to start. There is no such thing as qmake for Windows.
Can someone give me a few hints where to start. Please note that I don't know QT almost at all, my task is just to debug some issue unrelated to QT.
Are you using terminal exclusively on Windows? If so, maybe this image of example build steps straight from Qt Creater 4.14.2 may help you:
As you can see the image of the default Qt creator build steps list the file path where 'qmake.exe' can be located on a local installation of the toolchain.
If you can use a machine with a display I find using the Qt creator GUI is not all that bad.
Here is a link to the base get started page:
https://doc.qt.io/qt-5/gettingstarted.html
Here is a link to the installer download page:
https://www.qt.io/download
IMPORTANT:
You will need to make a Qt account, login to your account, and then download the open-source version of the API. The commercial version of the same source is acquired differently/seperately.
Otherwise, if you cannot use the GUI, can I request some clarification on why you cannot use Qt creator on your Windows installation?
I'm using Visual Studio 2015 Community to make a Qt-based GUI in C++ which includes a microphone input. I'm testing the microphone part, and am looping through QAudioDeviceInfo::AvailableDevices(QAudio::Mode::AudioInput) (and AudioOutput for that matter) and nothing is coming up. I've checked that my project includes QtMultimedia, and I definitely have audio devices on this computer. I'm stuck with an existing compiled Qt (since this application is plugging into another project), but I've verified that the Qt install has the QtMultimedia and the Windows audio plugins. The Qt version is 5.9.3.
The only thing I can think of is that the project isn't including the right plugin, but I don't know how to change that.
The issue was that I needed to run "windeployqt" on the built executable to get all of the plugins into the right place. I'm curious why it didn't work without that, but that's a VS + Qt plugin problem, not a Qt problem.
I'm using Debian Jessie and dmesg | grep video returns:
[ 22.280407] Linux video capture interface: v2.00
[ 22.790704] uvcvideo: Found UVC 1.00 device Lenovo EasyCamera (13d3:5170)
[ 22.796546] usbcore: registered new interface driver uvcvideo
The example compiles fine but upon launch i get a dialog telling me that the camera service is missing. I'm using Qt 5.5.0. This question points to a similar issue but it's for windows. Also I've installed Qt using the installer provided at it's web site. I've tested my webcam with Cheese application and it works but QCameraInfo::availableCameras() returns nothing.
I don't know if this is a definitive answer, but in my experience the dreaded "camera service is missing" comes down to exactly what the message says; for some reason the media back-end that Qt uses to get video input from a camera is broken or miss-configured in some way. In my case I had this problem in the following situations:
1. Building Qt from source
Qt build system SILENTLY DISABLES FEATURES if you don't have all the dependencies that it requires to include them in the build. Make sure to read this official article very carefully for your platform. I lost count of the times this has ruined my <insert favourite period of time such as day/week/year here >, and not only for the multimedia module...
2. Missing some gstreamer packages on my Ubuntu
I develop for Linux & Debian mostly, and on those platforms Qt depends on gstreamer backend. gstreamer is basically a plugin architecture in the core with every single feature added as plugins, and with endless possibilities of manual intervention through configuration files. See where is this is going? Clue: make sure you have all the plugins you want installed and configured properly. Here is a link to some gstreamer tools you can use. Same probably goes for other back-ends on other platforms.
And a pro tip in the end: Since both Qt5.5 gstreamer0.1 (old) and gstreamer1.0 (new) are supported as back-ends, and since Qt5.6 the new one is default. This will give you some room for experimenting, for example if the old does not work, you can try the new etc.
Hope this was useful!
In my QT GUI application I need playback some video files. I tried the MediaPlayer component (qtmultimedia 5.0), but it cannot read the video containers (mp4/mkv) that I'm using, which VLC player runs without any problem. So I found an library called vlc-qt (http://projects.tano.si/vlc-qt) and downloaded the windows binaries (which seem to be compiled using MSVC 11.0), but it fails to link on QT Creator MinGW (it shows 16 lines of undefined reference), maybe because vlc-qt is compiled with a different compiler than the one used to build the QT app.
I can't find any working references or documentation on this topic, so does anybody know how can I make this?
More details:
Windows 8.1 x64
QT Creator 3.0.1 | QT 5.2.1
vlc-qt 0.9.0
C++
Thank you.
The library is compiled using MSVC so it can not be liked to your application with a MinGW compiler. You can get the code from Here and compile it with MinGW compiler. After that you can link it to your app.
You can download and install CMake from Here. Next open the file named "CMakeLists.txt" from the root of the VLC_Qt source code with Qt Creator. Click "Next" and then after selecting the desired Generator click "Run CMake". WHen everything completes click finish. Now you can build the entire VLC-Qt with Qt Creator.
I have some code compiled using Visual Studio 2010 (C++), with Qt for the GUI and Phonon to show some videos.
I compile and run the code in a Windows XP machine and everything works fine. The videos and controls are shown correctly, and the same in other Windows XP machines. But at the moment that I try to use a Windows 7 machine, the video is not shown. Phonon controls are loaded, I can adjust the size of the Phonon VideoWidget but nothing is shown. I am using the SetFile method to indicate the file location and I have also tried (of course, with no luck) with setCurrentSource in the MediaObject (it works, though, in Windows XP).
I have tried different locations of files (absolute/relative) but nothing seems to work. Also, in XP when a video is not found an alert message is shown while in Windows 7 there is no error message, but also no video is shown. If I try to open the videos with other players, they work fine (I tried also with videos with different formats).
Any idea on what can be wrong? Is there something that I am missing with Phonon and Windows 7? Thanks!
When deploying your application to a different computer, make sure you don't forget to copy the Phonon backend. Not just the DLL contained in it (the ds backend for me), but also the directory itself.
That is
-Application Directory
¦-myexe.exe
¦-phonon_backend
¦-phonon_ds94.dll
Furthermore the Phonon backend on Windows (and Mac I think) makes use of the QtOpenGL module. So don't forget to copy this either. It can go inside the application directory.
In any case you could help yourself out a bit by adding a small bit of code that shows (perhaps writes to a file) which mimetypes are available. If it doesn't spit out anything, there is a problem with your backend. (Well, that of your application...)
This is what I had to do when I used Phonon to play video inside my application. Since I only quickly added this some time ago to my application, I'm not 100% sure that this is the only (or even the proper) way to do this, so anyone who has different insights feel free to comment on this.