[Interest] QtQuick and Video

[Mark]

On Tue, Nov 6, 2012 at 4:35 PM, Joseph Crowell
<joseph.w.crowell at gmail.com> wrote:
> On 11/5/2012 11:51 PM, Mark wrote:
>
> On Mon, Nov 5, 2012 at 2:42 PM, Robert Voinea <rvoinea at gmail.com> wrote:
>
> On Monday 05 November 2012 18:38:07 Pritam wrote:
>
> On Monday 05 November 2012 05:24 PM, Robert Voinea wrote:
>
> Hi
>
> Has anyone tried the QtQuick 1.0/1.1 and Video combination?
>
> I have to implement a simple interface for several video streaming sources
> in QML (one video "window" and several buttons that change the video
> source) and I don't seem to get it right.
>
> I am using ubuntu 12.10.
>
> QtMultimediaKit is installed, and phonon-backend-vlc... and
> phonon-backend-
> gstreamer. In system settings I have set vlc as the preffered phonon
> backend... But it get this on the console when I try to load a simple
> video
>
> (captured with VLC from my laptop's webcam):
>     (test:11708): GStreamer-CRITICAL **: gst_object_ref: assertion `object
>
> !=
>
> NULL' failed
>
>     (test:11708): GStreamer-CRITICAL **: gst_object_ref: assertion `object
>
> !=
>
> NULL' failed
>
>     (test:11708): GStreamer-CRITICAL **: gst_element_set_state: assertion
>
> `GST_IS_ELEMENT (element)' failed
> Apparently phonon ignores the vlc backend and always uses gstreamer.
> (any ideea how can I force phonon to use the vlc backend instead of
> gstreamer?)
> At this point I don't use streams... but a single file (OGG/Theora).
> This is my test file:
>
> import Qt 4.7
> import QtMultimediaKit 1.1
> Rectangle
> {
>
>     id: rootWindow
>     width: 1024
>     height: 768
>     Video
>     {
>
>             id: video
>             width: 640
>             height: 480
>             anchors
>             {
>
>                     centerIn: parent
>
>             }
>             fillMode: Video.PreserveAspectFit
>             source: 'test.ogv'
>
>     }
>
> }
>
> I have tried with both gstreamer and vlc backends. I don't care which one
> I
> have to use as long as I can set the source as an URL...
>
> At the moment I am considering writing my own QML element that displays a
> video stream using (probably) the native vlc API... or something like
> this:
> http://www.meegoexperts.com/2011/09/phonon-video-player-qml/.
>
> Thank you in advance! :)
>
> QtMultimediaKit or QtMultimedia doesnt depend on phonon. The backend for
> them on Linux is GStreamer.
> If you have gstreamer installed and still not able to play, test that
> gstreamer plugins required for your media are installed.
> To test that, you can try playing your media in Totem, it has plugin
> discovery built in. If it plays problem is with your Qt Build (if you
> built Qt yourself) or your qt code. If doesn't play it will tell you
> which  plugins to install.
>
> Thank you for clearing that up.
> I had the impression that QtMultimediaKit depended on phonon...
>
>
> _______________________________________________
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> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>
> Actually, that is (partly) true. The QtMultimedia CLASSES depend on
> phonon: http://qt-project.org/doc/qt-4.8/qtmultimedia.html
> But the new QtMultimedia module isn't the same as the current
> QtMultimedia module. The reason for that (afaict) is that
> QtMultimediaKit comes from QtMobility which doesn't exist in Qt5. So
> they took components of QtMobility and put them back in Qt as modules.
>
> I hope someone else can do a better job in explaining it..
>
> At the bottom of the linked document it states "The functionality provided
> by the Phonon Module is on a higher level and in many cases more suitable
> for application developers.". This doesn't mean the old QtMultimedia classes
> depended on Phonon and in fact, they didn't as they actually predated Phonon
> support. Also, if you look through QtMultimediaKit's source, at no point
> does it ever reference Phonon. Neither do the new QtMultimedia modules in
> Qt5. QtMultimedia/Kit does not depend on Phonon.

With that you seem to imply that it "could" use phonon while that is
not the case (or can it..?). The way i understand it the new
QtMultimedia "can" have a phonon backend if someone makes it. But that
hasn't been done so for now it's gstreamer only (on Linux).