QMediaPlayer Video Opens Second Window. Only One Desired. GStreamer Pipeline URI

[mbar]

I am trying to embed a video in a window with buttons. Here is my reduced Video Feed Widget example. When I run it in Linux 18.04 container, it opens two windows. I would like the "python3" window to show up in the "videoplayer.py" window.

import logging

from PySide2.QtCore import QSize, QUrl
from PySide2.QtMultimedia import QMediaPlayer, QMediaPlaylist
from PySide2.QtMultimediaWidgets import QVideoWidget
from PySide2.QtWidgets import QWidget, QVBoxLayout

logger = logging.getLogger(__name__)

class VideoFeedWidget(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent=parent)
        self.player = QMediaPlayer()
        self.resize(QSize(400, 300))

        uri = "gst-pipeline: videotestsrc ! ximagesink"
        self.player.setMedia(QUrl(uri))

        self.video_widget = QVideoWidget()
        self.player.setVideoOutput(self.video_widget)

        self.layout = QVBoxLayout()
        self.layout.addWidget(self.video_widget)
        self.setLayout(self.layout)

        self.player.play()

if __name__ == "__main__":
    from PySide2.QtWidgets import QApplication
    import sys
    app = QApplication(sys.argv)
    player = VideoFeedWidget()
    player.raise_()
    player.show()
    app.exec_()

[mbar]

The problem appears to be related to where you call player.setMedia. If I call it after setVideoOutput, everything works hunky dory

[SGaist]

Hi and welcome to devnet,

You should use the example pipeline provided in the QMediaPlayer::setMedia documentation. It shows how to properly setup the sink to use Qt as output.

One thing you are missing is the name of the sink.

[mbar]

I am not sure how to implement the AbstractSurface example in Python

class VideoFeedWidget(QWidget):
    class Surface(QAbstractVideoSurface):
        def __init__(self, parent=None):
            super().__init__(parent=parent)

    def __init__(self, parent=None):
        super().__init__(parent=parent)
        self.player = QMediaPlayer()
        self.resize(QSize(400, 300))

        uri = "gst-pipeline: videotestsrc ! qtvideosink"

        self.video_widget = self.Surface()
        self.player.setVideoOutput(self.video_widget)
        self.player.setMedia(QUrl(uri))
        self.player.play()

        # self.layout = QVBoxLayout()
        # self.layout.addWidget(self.video_widget)
        # self.setLayout(self.layout)

and got

root@213c9f3fd16c:/# python3 videoplayer.py 
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
Error: " videotestsrc ! qtvideosink" : "no element \"qtvideosink\""
AL lib: (EE) ALCplaybackAlsa_open: Could not open playback device 'default': No such file or directory
GStreamer; Unable to pause - "gst-pipeline: videotestsrc ! qtvideosink"
GStreamer; Unable to play - "gst-pipeline: videotestsrc ! qtvideosink"
libGL error: No matching fbConfigs or visuals found
libGL error: failed to load driver: swrast
Warning: "Failed to connect: Connection refused"
Error: "No URI handler implemented for \"gst-pipeline\"."

This works well enough. Throws a lot of "QWidget::paintEngine: Should no longer be called" errors though

class VideoFeedWidget(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent=parent)
        self.player = QMediaPlayer()
        self.resize(QSize(400, 300))

        uri = "gst-pipeline: videotestsrc ! xvimagesink name=\"qtvideosink\""

        self.video_widget = QVideoWidget()
        self.player.setVideoOutput(self.video_widget)
        self.player.setMedia(QUrl(uri))
        self.player.play()

        self.layout = QVBoxLayout()
        self.layout.addWidget(self.video_widget)
        self.setLayout(self.layout)

[mbar]

The problem appears to be related to where you call player.setMedia. If I call it after setVideoOutput, everything works hunky dory