[Interest] Playing MP4 and FLV with QMediaPlayer

Jason H scorp1us at yahoo.com
Thu Sep 12 19:53:43 CEST 2013


You can use the windows 'graphedit' program to view the rendering graph. It might point you in the right direction in terms of what is missing. It is like depends.exe but for media.


________________________________
 From: Jason Kretzer <Jason at gocodigo.com>
To: Jason H <scorp1us at yahoo.com>; Lopes Yoann <Yoann.Lopes at digia.com>; Mandeep Sandhu <mandeepsandhu.chd at gmail.com> 
Cc: "interest at qt-project.org" <interest at qt-project.org> 
Sent: Thursday, September 12, 2013 10:55 AM
Subject: RE: [Interest] Playing MP4 and FLV with QMediaPlayer
 

I actually tried that last night.  Still getting a black box.

From: Jason H [mailto:scorp1us at yahoo.com] 
Sent: Thursday, September 12, 2013 10:35 AM
To: Lopes Yoann; Mandeep Sandhu
Cc: Jason Kretzer; interest at qt-project.org
Subject: Re: [Interest] Playing MP4 and FLV with QMediaPlayer

On the Win7 box, try installing "KLite Codec Pack" that usually works for me.


________________________________________
From: Lopes Yoann <Yoann.Lopes at digia.com>
To: Mandeep Sandhu <mandeepsandhu.chd at gmail.com> 
Cc: Jason Kretzer <Jason at gocodigo.com>; "interest at qt-project.org" <interest at qt-project.org> 
Sent: Thursday, September 12, 2013 4:30 AM
Subject: Re: [Interest] Playing MP4 and FLV with QMediaPlayer

On Windows 7, Media Foundation is the default backend. DirectShow is the default only on Windows XP (or with MinGW-built Qt on any version of Windows).  
The problem with Media Foundation is its limited codec support, see http://msdn.microsoft.com/en-us/library/windows/desktop/dd757927(v=vs.85).aspx . DirectShow doesn't have this problem and virtually supports anything (through third-party codecs).

Because of this, we are planning to do like Windows Media Player and implement a dynamic backend selection that would pick the one supporting the media the user wants to load. You can track this task there https://bugreports.qt-project.org/browse/QTBUG-32783

As for the original problem, it might be a missing codec or a bug... 
If you want support for more codecs, you should force Qt to use the DirectShow plugin. You'll either have to use the MinGW packages or get the Qt sources ('stable' branch) and configure Qt with '-no-wmf-backend'.

Yoann Lopes
Senior Software Engineer - Digia, Qt
Visit us on: http://qt.digia.com 

On Sep 12, 2013, at 6:57 AM, Mandeep Sandhu wrote:



The trick is this, I can put this on several different machines - all are Windows 7 Pro:
1.) machine 1 - development box, can play some mp4s but not others (all h264)
2.) machine 2 - personal household box, will play the sampleFile mp4 sometimes
3.) machine 3 - COMPLETELY clean windows 7 pro install, aside from the code above, has nothing installed on it, NEVER plays the mp4.

All 3 machines can play the sampleFile.mp4 in Windows Media Player.

As a final note, none of these will play FLV either.

Pointers anyone? What am I missing here?

QtMultimedia relies on 'backends' to work on different OS'. For Windows I think it uses 'DirectShow'. Is that installed and working properly on the machines you're trying?
Here's more detail on the state of art:
http://qt-project.org/wiki/Qt_Multimedia_Backends
Places where video is not playing, it's possible that there's no support for the codec/container in the backend being used (DirectShow or some other).

HTH,
-mandeep

 

Thanks!

-Jason





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