[Interest] Phonon video

Jason H scorp1us at yahoo.com
Thu Mar 29 15:48:05 CEST 2012

I thought QtMultimediaKit was the way to go?

I would suspect that something in the DS filter graph changed. Verify you have a valid path for the file type you are trying to play: http://msdn.microsoft.com/en-us/library/ms787460.aspx
Keep in mind you still need to install video codecs because mingw version of Qt does not work with Windows7's new media interfaces. Installing K-Lite Codec pack usigally works for me.

----- Original Message -----
From: Bo Thorsen <bo at fioniasoftware.dk>
To: Qt Project MailingList <interest at qt-project.org>
Sent: Thursday, March 29, 2012 8:34 AM
Subject: [Interest] Phonon video

Hi people,

I've been trying to figure out why phonon suddenly doesn't work anymore. 
It plays audio just fine but not video. I'm completely stuck.

I built and ran the qmediaplayer demo and saw the same thing, so it's 
not my code. And the same code plays the files just fine on Linux. But 
just for reference, here it is anyway:

     mPlayer = new Phonon::MediaObject(this);
     mVideo = new Phonon::VideoWidget;
     Phonon::createPath(mPlayer, mVideo);
     if (!mPlayer->hasVideo()) {
         qDebug() << "Phonon video sink is not available";

hasVideo() returns false, and any attempt at adding a video file to 
Phonon gives me a "Pause Called" in the debug output window. This is the 
code used to play a file:

     mVideo->resize(200, 200);

Calling Phonon::BackendCapabilities::availableMimeTypes() gives me a 
list of 54 mimetypes with both audio and video types in it. The files 
I'm trying to play are supported, and Windows Media Player plays them 
just fine.

Now here's the really strange part: Last week it worked. But suddenly, 
video playback is gone. I have no clue what happened in between. I might 
have updated Windows, but if that breaks Phonon, we have a real problem.

I can see that the DS94 backend is still there in both my 4.8.0 and 
4.7.4 plugins.

This really worries me. The code is for a customer with an embedded 
system that's going to be deployed on machines in many countries. 
Calling those back to fix a Phonon problem *is not* an option. If Phonon 
can't deliver a stable environment (and I currently seriously doubt 
this), I will have to ditch it.

I obviously tried to search the net for this, and found plenty of people 
with the same result. But none with a solution for it. I hope someone 
here can help.

I'm on Windows 7 x64 and Windows XP 32 bit, using a fully updated SDK 
2.4.1 with both visual studio 8 and mingw compilers and Qt versions 
4.8.0 and 4.7.4.

Bo Thorsen,
Fionia Software.


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