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  1. #1
    Registered User
    Join Date
    Jun 2011
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    8

    QMediaPlayer with QGraphicsVideoItem issue

    Hi,

    I write a custom video player code (QDeclarativeItem subclass) and I got problems with video playback. I use this:
    Code:
    player = new QMediaPlayer(this);
    videoSurface = new QGraphicsVideoItem(this);
    player->setVideoOutput(videoSurface);
    videoSurface->show();
    The videos are played correctly, but if I set in main.cpp this:
    Code:
    app.data()->setGraphicsSystem("raster");
    video is black. This code works flawless in N950, but it doesn't in on C7 with Symbian Belle.
    I also tried subclassing QAbstractVideoSurface instead of QGraphicsVideoItem, but "start()" isn't called.

    Thanks in advance for any suggestions

  2. #2
    Nokia Developer Expert
    Join Date
    Sep 2011
    Posts
    382

    Re: QMediaPlayer with QGraphicsVideoItem issue

    Videoplayback on Symbian C7 is a complex issue. For example, audio only (black screen) may happen due to overlay cause software rendering. When CPU hits 100% ; the master clock is audio and the frames are dropped as they are decoded late. Unless CPU cycles are not freed up, nothing can be done by the post processor. They need at least 10% of CPU slice. They go into a continuous cycle where every frame arrives too late and will be discarded by post-processor. Is something using raster/sw rendering ? On N8 top level QWidgets with Qt::WA_TranslucentBackground fallback to software rendering because hw accelerated transparent EGL surfaces are not supported.

  3. #3
    Registered User
    Join Date
    Jun 2011
    Posts
    8

    Re: QMediaPlayer with QGraphicsVideoItem issue

    thanks Devnull

    I will try a different approach since I need a custom video element.

  4. #4
    Regular Contributor
    Join Date
    Mar 2012
    Posts
    144

    Re: QMediaPlayer with QGraphicsVideoItem issue

    hi lildeimos

    for best performance you have to use opengl graphics system and avoid qwidgets in this case

  5. #5
    Registered User
    Join Date
    Jun 2011
    Posts
    8

    Re: QMediaPlayer with QGraphicsVideoItem issue

    Hi vladestCh

    thank you, but I have the same problem using "opengl" as graphycs system.
    I read here that the QML Video element uses QMediaPlayer with QVideoWidget as surface ( I still need to see the Qt code ). I also thougth to avoid the use QWidget on Anna+, but seems to be the only option.

  6. #6
    Regular Contributor
    Join Date
    Mar 2012
    Posts
    144

    Re: QMediaPlayer with QGraphicsVideoItem issue

    hi

    then may be it makes sense to create your own declarative item, based on QGraphicsVideoItem

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