[Phonon-Mplayer] No video shown when using with QGraphicsProxyWidget

Tanguy Krotoff tkrotoff at gmail.com
Fri Oct 16 02:02:35 CEST 2009

So to sum up (correct me if I'm wrong)

QGraphics* classes don't rely on standard X11 windows (win32 HWND
under Windows).

VLC and MPlayer (Xine too I guess) get the QWidget::WId (internal OS
widget ID) to paint directly on it and this cannot work with
QGraphics* classes. QGraphics needs to get the real data of each video
frame, typically a char * (so no acceleration).
For every video frame (30fps): backend --> video frame (char *) -->
QImage --> QGraphics*

Since the only way to control MPlayer is by sending commands to the
/usr/bin/mplayer process (no C API), QGraphics* will never work with
VLC comes with libvlc (like Xine, GStreamer...) so it can potentially
work if a function allows to get the video frames (char *). I've
checked libvlc and no function of this kind currently exist.

I know for sure DirectShow and QuickTimes allow this, I have done it
in the past for webcam video frames.

Here comes the limits of MPlayer and VLC (Xine too?) who are not
really designed
to be multimedia frameworks like GStreamer, DirectShow and QuickTime.

On Wed, Oct 14, 2009 at 7:43 PM, Martin Sandsmark
<sandsmark at samfundet.no> wrote:
> On Thu, Oct 15, 2009 at 01:39:46AM +0800, Ben Lau wrote:
>>   Then the video will be shown , but not on top , it is covered by the
>> QGraphicsView itself . I can only see the border is changing. I have
>> no idea how to solve it yet.. (See attached screenshot and source
>> code)
> The VideoWidget requires direct rendering to get any kind of performance. The
> right way to solve your problem would be to use Experimental::VideoDataOutput
> to get the video frames and display them in the QGraphicsView, AFAIK.
> Unfortunately, I don't think Phonon-MPlayer has any support for
> VideoDataOutput (and the support in Phonon-Xine is kind of broken. I'm poking
> a bit at it to get Quasar working again, but I haven't really found out why
> yet).
> Sorry, but I don't really have any good answers. :-(
> --
> Martin Sandsmark
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> Phonon-backends mailing list
> Phonon-backends at kde.org
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Tanguy Krotoff <tkrotoff at gmail.com>
+33 6 68 42 70 24

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