Showing a mp4 in my app

[MichRX7]

Help! I'm trying to simply show a mp4 video in my app and am struggling.

I have a pushbotton, and when clicked I want it to play a video from my file system inside the app.

When I input this code and click on the button it seems to actually open a whole new app, but the new app doesn't play the video.

    QWidget *widget = new QWidget;
    widget->resize(400, 300);
    QMediaPlayer *player = new QMediaPlayer;
    QVideoWidget *vw = new QVideoWidget;
    player->setVideoOutput(vw);
    player->setMedia(QUrl::fromLocalFile("/home/pi/Videos/tomtiph.mp4"));
    player->setVolume(50);
    player->play();
    widget->show();
    qDebug() << "mediaStatus: " << player->mediaStatus() << "error: " << player->error();

Obviously, in the end, I'd like to have the QVideoWidget on the mainwindow and play there, but for now I'd just be happy to see a video playing.

[SGaist]

Hi

You forgot to call show on the QVideoWidget.

[MichRX7]

Ok, so I added vw->show(); below widget->show(); which opens another window, but still I don't see the video. I also tried moving the line player->play(); below vw->show(); but no video. Am I calling the setMedia properly?

[SGaist]

You should connect the error signal to see if something wrong is happening.

[MichRX7]

@SGaist said in Showing a mp4 in my app:

You should connect the error signal to see if something wrong is happening.

Well, I do the qDebug and the debugger is showing the following:
mediaStatus: QMediaPlayer::LoadingMedia error: QMediaPlayer::NoError

That's why I was wondering if I'm doing this line wrong:
player->setMedia(QUrl::fromLocalFile("/home/pi/Videos/tomtiph.mp4"));

[SGaist]

If there is no error, then the signal is not emitted. When exactly are you using that qDebug ?

[MichRX7]

When the button is pushed this is the block of code that runs:

    QWidget *widget = new QWidget;
    widget->resize(400, 300);
    QMediaPlayer *player = new QMediaPlayer;
    QVideoWidget *vw = new QVideoWidget;
    player->setVideoOutput(vw);
    player->setMedia(QUrl::fromLocalFile("/home/pi/Videos/tomtiph.mp4"));
    player->setVolume(50);
    widget->show();
    vw->show();
    player->play();
    qDebug() << "mediaStatus: " << player->mediaStatus() << "error: " << player->error();

If there is a better way to do this, please enlighten me. I know we've talked privately about using qstackedwidget so I can show/hide the video widget and was going to play with that right after I actually get a video to play, lol...

[SGaist]

As I wrote, connect the error signal (the name is confusing since the accessor has the same name but a different signature, there's work in progress to make that cleaner).

Calling the getter right after play won't help because your file is not even loaded.

[MichRX7]

Ok, so now I'm frustrated and confused.

I simply want to show a video from my local file system in my app. Is this really that difficult? Does anyone have a block of code they would be willing to share that does this? I don't need player controls or anything, just play a video and stop.

[J.Hilk]

@MichRX7 said in Showing a mp4 in my app:

Ok, so now I'm frustrated and confused.

I simply want to show a video from my local file system in my app. Is this really that difficult? Does anyone have a block of code they would be willing to share that does this? I don't need player controls or anything, just play a video and stop.

The official example ?
https://doc.qt.io/qt-5/qtmultimedia-multimediawidgets-videowidget-example.html
🤷‍♂️

[MichRX7]

@J-Hilk Thank you, will try that during my lunch break. For some reason none of the examples are showing up for me in QT Creator. I'll bring that code down and go through it. I tried bringing down the media player with play list example, and it didn't play anything when I hit play.

[MichRX7]

@J-Hilk

Thank you for pointing me at the official example. I downloaded the files and open the project in QT Creator, hit F5 and wait, the app pops up, I click the Open button, select my mp4 and click the play button and... nothing. I have tried multiple videos and can play those videos with VLC.

[SGaist]

Are they all mp4 ?

Did you try a different format ?

The fact that they play in VLC is a good sign that they are not corrupted however it does not mean that your system has all the required codecs.

On a side note, you can also make use of VLC in your Qt application if you want.

[MichRX7]

@SGaist said in Showing a mp4 in my app:

On a side note, you can also make use of VLC in your Qt application if you want.

And this is where my non-linux kicks in. I cloned the VLC-QT git directory, but now I don't know what to do from there. I believe I have to build it from within the debian sub-folder inside of the vlc-qt directory, but no idea how.

[MichRX7]

So, following this page for install directions on the vlc-qt: https://github.com/vlc-qt/vlc-qt/blob/master/BUILDING.md

It says for Linux:
Linux
Install requirements from your distribution's repository. Supported generators are make and ninja.

Make example:

$ mkdir build
$ cd build
$ cmake .. -DCMAKE_BUILD_TYPE=Debug
$ make -j8
$ make install

So, I go into the git debian directory because I believe my Rpi4 is running raspbian debian stretch. I then do the mkdir build and cd build so I'm in the build subdirectory of debian. I then use the following cmake command:
cmake -SYSTEM_QML -WITH_X11 -DCMAKE_BUILD_TYPE=Debug

And I get the following error:
CMake Error: The source directory "/home/pi/vlc-qt/debian/-dcmake_build_type=Debug" does not exist.
Specify --help for usage, or press the help button on the CMake GUI.

Was I supposed to put something else where the ".." is in the cmake directions?

[jsulm]

@MichRX7 You need to tell cmake where the source code is:

cmake PATH_TO_SRC -SYSTEM_QML -WITH_X11 -DCMAKE_BUILD_TYPE=Debug

[MichRX7]

@jsulm Thanks for the quick reply.

In the interim I did get a .mov file straight from a new iPhone and moved that over onto my Rpi4, and guess what. It plays, so it must be a codec issue on the mp4 (though it didn't have sound, but maybe the Rpi4 doesn't output sound through hdmi).

Is there a page that tells newbies like me how to install the right codec for my mp4 videos?

[MichRX7]

Hahaha, of course though I take a .mp4 into my video editing software and export it is a .mov and it won't play either. So is there a way to tell what I need to do to a video to get it to play or how I install the codec's I need in QT? I don't want to have to use only non-edited iPhone vids, lol...

(Seriously, so glad to just see a video play... thank you all for the help so far.)

[jsulm]

@MichRX7 Most safe method is to install all GStreamer plug-ins your distribution is providing.

[MichRX7]

@jsulm And I'm stuck again (of course), so I did the following on my Rpi4:
sudo apt-get install gstreamer1.0-tools
Reading package lists... Done
Building dependency tree
Reading state information... Done
gstreamer1.0-tools is already the newest version (1.14.4-1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

So, I already had the newest version of gstreamer installed. Is there something else I need to do to download specific codec's or all codec's? I tried going to the gstreamer website, but not seeing anything on codecs.