Qt Multimedia Issues
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Hello,
I am nearing completion of a Qt project and am running into several issues related to playing a video stream (webcam). I have tried a few versions of Qt to solve the issue and have different results and could use some guidance. This is using Qt C++
I have not been able to test the example media player because it's a qtquick application but also confirmed these results in isolated projects using code snippets from Qt Docs
Qt version 6.6.3 GCC 64 QVideoWidget & QMediaPlayer
Host: Linux 64bit (wayland)Most of the gui is frozen when I switch pages to the one with QVideoWidget. Animations stop running and signals/slots from the parent widget of QVideoWidget stop functioning. Other gui elements (like my menu buttons) still respond.
Qt version 6.6.3 GCC 64 QGraphicsVideoItem & QMediaPlayer
Host: Linux 64bit (wayland)Setting up the video in a QGraphicsView/Scene seems to mostly function. It plays the webcam stream without issue...until I resize it. I seem to have to leave it in it's native resolution - otherwise it's filled with green bars whose size depends on how much I've scaled the video. In the screenshots I changed the aspect ratio to show this.
Qt version 6.7.1 GCC 64 QGraphicsVideoItem & QMediaPlayer
Host: Linux ARM64 (wayland)Just got a new raspberry pi 5 and wanted to see if the banding issue was present on there too. The installer is only letting me choose Qt6.7+. Got everything setup (at least whats needed for my desktop environment) and this results in a black screen with qt complaining about no Multimedia Backends being available. I have ffmpeg and libva packages installed.
Some googling suggests this is an issue introduced recently with 6.7.0 but cannot confirm that and the preview of 6.8.0 is the same.
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For the issues with video streaming in your Qt project:
QVideoWidget Freezing: Move video processing to a separate thread to prevent GUI freezing.
QGraphicsVideoItem Green Bars: Check resizing logic and maintain aspect ratio during resize.
No Multimedia Backends on Raspberry Pi: Ensure all required multimedia backend packages are installed and configured for Qt.
Consider visiting Qt forums for more detailed support if needed. -
For the issues with video streaming in your Qt project:
QVideoWidget Freezing: Move video processing to a separate thread to prevent GUI freezing.
QGraphicsVideoItem Green Bars: Check resizing logic and maintain aspect ratio during resize.
No Multimedia Backends on Raspberry Pi: Ensure all required multimedia backend packages are installed and configured for Qt.
Consider visiting Qt forums for more detailed support if needed.@vincent9874 said in Qt Multimedia Issues:
For the issues with video streaming in your Qt project:
QVideoWidget Freezing: Move video processing to a separate thread to prevent GUI freezing.
QGraphicsVideoItem Green Bars: Check resizing logic and maintain aspect ratio during resize.
No Multimedia Backends on Raspberry Pi: Ensure all required multimedia backend packages are installed and configured for Qt.
Consider visiting Qt forums for more detailed support if needed.Thank you for your responding :)
QVideoWidget Freezing: there is no media playing at the time of it freezing - the media is loaded after the page load. Just having it on the actively visible widget causes it to lockup.
QGraphicsVideoItem Green Bars: I am maintaining the aspect ratio of the source. For the examples I changed my camera config from 16:9 to 4:3 to show how the bars propagate differently based on size. If I do it on my isolated project the bars change in size and frequency as I resize the window.
Raspberry pi: ffmpeg, libav and gstreamer are all installed and Qt 6.5+ should be configured for ffmpeg by default.
What forums do you suggest? A sub here or like qt centre?
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@vincent9874 said in Qt Multimedia Issues:
For the issues with video streaming in your Qt project:
QVideoWidget Freezing: Move video processing to a separate thread to prevent GUI freezing.
QGraphicsVideoItem Green Bars: Check resizing logic and maintain aspect ratio during resize.
No Multimedia Backends on Raspberry Pi: Ensure all required multimedia backend packages are installed and configured for Qt.
Consider visiting Qt forums for more detailed support if needed.Thank you for your responding :)
QVideoWidget Freezing: there is no media playing at the time of it freezing - the media is loaded after the page load. Just having it on the actively visible widget causes it to lockup.
QGraphicsVideoItem Green Bars: I am maintaining the aspect ratio of the source. For the examples I changed my camera config from 16:9 to 4:3 to show how the bars propagate differently based on size. If I do it on my isolated project the bars change in size and frequency as I resize the window.
Raspberry pi: ffmpeg, libav and gstreamer are all installed and Qt 6.5+ should be configured for ffmpeg by default.
What forums do you suggest? A sub here or like qt centre?
@DigitalArtifex I guess this is more a Qt issue than a FFmpeg or gstreamer problem. If you run a FFmpeg pipeline from command line and a default windows pops up, you may not have any freezing problem with the widget. It could be an issue if Qt widget is resized too quickly, for example.
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@DigitalArtifex I guess this is more a Qt issue than a FFmpeg or gstreamer problem. If you run a FFmpeg pipeline from command line and a default windows pops up, you may not have any freezing problem with the widget. It could be an issue if Qt widget is resized too quickly, for example.
Thank you, it does seem to be a Qt issue with Gnome. I had issues with QVideoWidget, QWidget::createWindowContainer and QColorDialog::getColor corrupting the rendering of my application.
Out of desperation I switched everything to KDE and it works as expected.
The raspberrypi was my fault and fixed it by explicitly specifying the backend
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N Nhan Nguyen moved this topic from General and Desktop on
