QtVideoWidget Video Stretching

neod

Hello,

I am using a QVideoWidget to display a video in my application. Although I have KeepAspectRatio set, when I resize the window the video becomes stretched (see image).

video window

I would like the aspect ratio of the video to be maintained. Any idea how I can achieve this? My current widget code is below.

class Editor(QWidget):

    def __init__(self, video_filename, parent=None):
        super().__init__(parent)
        main_layout = QVBoxLayout()

        video = QVideoWidget()
        video.setAspectRatioMode(Qt.KeepAspectRatio)
        main_layout.addWidget(video)

        play_button = QPushButton("Play")
        play_button.clicked.connect(self.play)
        main_layout.addWidget(play_button)

        self.player = QMediaPlayer()
        self.player.setMedia(QUrl.fromLocalFile(video_filename))
        self.player.setVideoOutput(video)

        self.setLayout(main_layout)

    @Slot()
    def play(self):
        self.player.play()

neod

Just a follow up, the desired output is something like the image below where the aspect ratio of the video is preserved.

Currently, when I resize the window, the video flickers and seems to preserve the aspect ratio with black bars like in the image above, but when I release the cursor the video becomes stretched.

I'm on Ubuntu 18.04 with GStreamer 1.14.5 and Qt 5.15.0

neod

I couldn't get QVideoWidget to maintain the video's aspect ratio. Maybe this is a bug in QVideoWidget? I managed to get it working by switching to QGraphicsVideoItem on a QGraphicsView. Others may find my code below useful.

class Editor(QWidget):

    def __init__(self, video_filename, parent=None):
        super().__init__(parent)
        main_layout = QVBoxLayout()
        self.setContentsMargins(0, 0, 0, 0)
        self.setMinimumSize(640, 480)

        self.item = QGraphicsVideoItem()
        self.item.setAspectRatioMode(Qt.KeepAspectRatio)
        self.scene = QGraphicsScene(self)
        self.scene.addItem(self.item)
        self.scene.setBackgroundBrush(Qt.black)
        self.view = QGraphicsView(self.scene)
        self.view.setRenderHint(QPainter.Antialiasing, True)
        self.view.setRenderHint(QPainter.SmoothPixmapTransform, True)
        self.view.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.view.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        
        main_layout.addWidget(self.view)

        self.player = QMediaPlayer(self, QMediaPlayer.VideoSurface)
        self.player.setMedia(QUrl.fromLocalFile(video_filename))
        self.player.setVideoOutput(self.item)

        self.setLayout(main_layout)
        self.player.play()

    def resizeEvent(self, event: QResizeEvent):
        self.view.fitInView(self.item, Qt.KeepAspectRatio)

The image quality of the video is not as good as QVideoWidget. Setting SmoothPixmapTransform and Antialising render hints improved it a little, but it's still below par. Any tips to improve this would be great.