[Development] QtMultimedia && QML - hard performance regressions on Windows

Massimo Callegari massimocallegari at yahoo.it
Wed Apr 27 15:44:44 CEST 2016


________________________________
Da: Mitch Curtis <mitch.curtis at qt.io>
A: Massimo Callegari <massimocallegari at yahoo.it>; "development at qt-project.org" <development at qt-project.org> 
Inviato: Mercoledì 27 Aprile 2016 14:56
Oggetto: RE: [Development] QtMultimedia && QML - hard performance regressions on    Windows



>I didn't look at the other bugs, but QTBUG-37004 seems like it would pretty easy to contribute a fix yourself. 

I don't believe it is pretty easy, especially on Linux. 
OSX already returns a user friendly list of devices.
Windows cuts the devices names to 31 characters, cause it use APIs coming directly from the 90s.
Linux is the worst case instead, cause every possible ALSA device is returned, so if you have 2 sound cards it will return like 20 devices, most of which don't even work.
I believe users expect to see a list like what KDE/Gnome expose, so 4-5 devices total.
Plus I should be looking at the pulseaudio implementation as well, which I know nothing about.
In any case, it would require an internal change of the logic, most likely breaking backward compatibility, which is not something that I can decide.

> Why waste your time and energy being outraged when you could be fixing it? Seems like a far more effective way of getting things fixed in an open source project. 

Well, I believe reporting an issue is already a contribution to fixing it and while a "pretty easy" issue would take me 1 hour to be fixed, the overall effort to get it approved would be 100 hours. I already went through the process for a QtSerialPort method, and it was a hell of a journey. Especially working with Gerrit. Please excuse my limited GIT knowledge :(

> As said in the bug report, higher priority issues are being worked on.

Which one ?
And also...since 1-2 years ? Right...


I would rather appreciate much more if the Qt Company could start a sort of "bounty program", where users can place a few bucks for the resolution of specific issues.
There are more and more examples of this mechanism, like Kickstarter, Bountysource or even Stackoverflow.
I would be happy to participate to it for the most urgent issues affecting my projects.
I'm pretty sure there are a lot of open source projects raising donations, and small companies willing to spend some money on issues that are a priority for them.

Instead, it seems to me (and it's purely my mere assumption) that big bucks come from big companies and they have the full attention of the Qt developments.
Attention that don't go to all the rest of minor developers/projects/companies that are actually the largest user base of the Qt libraries.
If this is really the truth, it is pretty sad. Again, just my opinion.

> 
> ________________________________
> Da: Denis Shienkov <denis.shienkov at gmail.com>
> A: "development at qt-project.org" <development at qt-project.org>
> Inviato: Mercoledì 27 Aprile 2016 11:37
> Oggetto: [Development] QtMultimedia && QML - hard performance regressions
> on    Windows
> 
> 
> 
> Hi developers.
> 
> I faced with a big problem with the video playback performance, when I
> try to open the mp4 video file from any of QML video examples. I have a
> high CPU loading (~40%) and the video is freezing and jerks. But the C++
> media player works satisfactory, more or less tolerably (on point 3 from
> the 1-5 points)...
> 
> It is impossible to use at all in QML, I face more and more with the
> surprises of QtMultimedia, and disappointed more and more...
> 
> WTF ? What sense in QtMultimedia if it does not work as expected?
> 
> PS: I have created a bug: https://bugreports.qt.io/browse/QTBUG-53019
> 
> BR,
> Denis
> 
> 
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