Video playback broken with Qt 5.5

Thumbnailing works however fine, but the video does not play in Media Player.

Videos in YouTube work, and the id used in qtvideo-node is still at the /5.2 it was adapted to during http://bazaar.launchpad.net/~phablet-team/qtvideo-node/trunk/revision/49

Can you get the log for mediaplayer-app as well? This will have the qtmultimedia/qtubuntu-media debug output.

Not much to be seen here. It now eventually crashes, attaching the crash file too.

The .crash file is not of much help without debug symbols though.

Ok it's possible to gdb -p [pidofmediaplayer-app] to get:

#0 0xb636a580 in QObject::staticMetaObject () from /usr/lib/arm-linux-gnueabihf/libQt5Core.so.5
#1 0xb0711c34 in QDeclarativeVideoRendererBackend::updatePaintNode (this=0x8bd328, oldNode=0xad30a070, data=<optimized out>)
    at qdeclarativevideooutput_render.cpp:319
#2 0xb69f15ce in QQuickWindowPrivate::updateDirtyNode (this=this@entry=0x7bd658, item=item@entry=0x868eb0)
    at items/qquickwindow.cpp:2985
#3 0xb69f1af4 in QQuickWindowPrivate::updateDirtyNodes (this=this@entry=0x7bd658) at items/qquickwindow.cpp:2723
#4 0xb69f1c2c in QQuickWindowPrivate::syncSceneGraph (this=this@entry=0x7bd658) at items/qquickwindow.cpp:341
#5 0xb69d2274 in QSGRenderThread::sync (this=this@entry=0x90bf38, inExpose=inExpose@entry=false)
    at scenegraph/qsgthreadedrenderloop.cpp:512
#6 0xb69d2a64 in QSGRenderThread::syncAndRender (this=this@entry=0x90bf38) at scenegraph/qsgthreadedrenderloop.cpp:558
#7 0xb69d6776 in QSGRenderThread::run (this=0x90bf38) at scenegraph/qsgthreadedrenderloop.cpp:674
#8 0xb60a8106 in QThreadPrivate::start (arg=0x90bf38) at thread/qthread_unix.cpp:331
#9 0xb5df6490 in start_thread () from /lib/arm-linux-gnueabihf/libpthread.so.0

That's probably as far as I can get there, and the trace doesn't show any hints why video playback works for eg thumbnailer + in Youtube but not in media-player - nothing related to qtvideo-node shown for example, and the backtrace does not go further back because of corrupt stack.

Any help welcome.

Thanks Timo. It looks like this is a regression or change of behavior in how the Qt threaded renderer works. Perhaps it has a new requirement for how a QSGVideoNode needs to be setup. Another thought: we brought QSGVideoNode into qtubuntu-media, maybe the definition used by the threaded renderer loop has changed for Qt 5.5 and we need to update our local copy of it.

Right, you mean qtvideo-node. Thanks for reminding about the inclusion of those private headers, they had indeed changed.

With the attached MP video playback works again.

downgrade since we will not move to 5.5 near term

This bug was fixed in the package qtvideo-node - 0.2.1+16.04.20151104-0ubuntu1

---------------
qtvideo-node (0.2.1+16.04.20151104-0ubuntu1) xenial; urgency=medium

  [ CI Train Bot ]
  * New rebuild forced.

  [ Timo Jyrinki ]
  * Port to Qt 5.5 to fix video playback (LP: #1474695) (LP: #1474695)

 -- CI Train Bot <email address hidden> Wed, 04 Nov 2015 08:20:56 +0000