[solved] QAudioOutput works in example project, doesn't work in my project

[billconan]

hello,

I'm facing a very weird issue. I want to add audio play to my project, so I first tried Qt's AudioOutput example. it compiles and works well. so I copied the same code to my project (same QAudioFormat):

@
m_format.setSampleRate(48000);
m_format.setChannelCount(2);
m_format.setSampleSize(16);
m_format.setCodec("audio/pcm");
m_format.setByteOrder(QAudioFormat::LittleEndian);
m_format.setSampleType(QAudioFormat::SignedInt);

    QAudioDeviceInfo info(QAudioDeviceInfo::defaultOutputDevice());
    if (!info.isFormatSupported(m_format)) {
        qWarning() << "Default format not supported - trying to use nearest";
        LOG(ERROR, MISC, 0, "Default format not supported - trying to use nearest");
        m_format = info.nearestFormat(m_format);
    }

@

however, in my project, QAudioDeviceInfo::defaultOutputDevice() always return null device.

I couldn't see any issue at all. so I copied the same code again to a completely new project's main function, and it worked.

it just won't work in a specific project. I start to think maybe my .pro settings are wrong or something. I can't figure this out.

[edit: Added missing coding tags @ SGaist]

[SGaist]

Hi,

Did you compare the working project and your pro file ?

[maximus]

If you have the time, you can look up SFML
http://www.sfml-dev.org/
really easy to integrate with Qt and it's easier to use that all Audio classes in Qt IMO

Good luck!

[billconan]

Thank you

Our project is quite large, it is not easy to strip it down and make it compile.

I will debug Qt instead. I feel that it might have something to do with the lib, flags used by the project.

[quote author="SGaist" date="1423781265"]Hi,

Did you compare the working project and your pro file ?[/quote]

[billconan]

will certainly try this!

Thanks
[quote author="maximus" date="1423782750"]If you have the time, you can look up SFML
http://www.sfml-dev.org/
really easy to integrate with Qt and it's easier to use that all Audio classes in Qt IMO

Good luck![/quote]

[billconan]

after debugging Qt, I realized that the issue is
QFactoryLoader can't load the audio plugin for my project even the inputs I provide seem to be the same between the working case and the failed case.

I'm still debugging QFactoryLoader to see how it works.

[billconan]

Ok, so the root cause is in the failed case, we called:
QCoreApplication::setLibraryPaths(QStringList(QCoreApplication::applicationDirPath()));

before setting up audio. This path doesn't contain the default Qt plugins, so it can't find the audio plugin dll for windows.

[SGaist]

Why are you making this call ?

[billconan]

this is a joint project with many people. I don't why and who added this code.