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QML video speed

  • I'm trying to simply play a .mov video in QML. Nothing else.

    I can get it to start, but on a new 2011 Macbook, it's choppy and slow. I really like QML, and I'd love to use it, but if I can't get reasonable performance out of it, I can't use it.

    Any thoughts on where to start looking into this? I'm curious if the wrong backend is somehow being chosen (not utilizing the capabilities of my graphics card), or some other thing is coming into play. The same video is fantastic with QtWebkit, on the same machine.

  • Here's the code, if that's helpful. Also includes the hack i put in to loop the video, which is NOT where the slowdown is coming from.

    Video {
    anchors.fill: parent
    source: "/background.mov"

        MouseArea {
            anchors.fill: parent
            onClicked: {
        focus: true
        playing: true
        Keys.onLeftPressed: video.position -= 5000
        Keys.onRightPressed: video.position += 5000
        onStopped: {
            console.log("Starting to loop back");
            position = 0
            playing = true
            console.log("Done looping back")


  • Also, this seems to grow in memory usage by about 50-100MB/s, which is insane.

    Is this just not being used by anyone? Just not on a mac?

    I used the latest released qt-mobility compiled from scratch, if that's helpful.

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