[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.