Diagnosing audio problems

SGaist · wrote on 19 Apr 2016, 19:58

Did you check that you have all QtMultimedia plugins installed ?

nulluse · wrote on 19 Apr 2016, 20:27

Oh, on Unix that would be

PulseAudio (Unix)
Alsa (Unix)

That may be the case: FreeBSD comes with OSS and Alsa is optional. I did not have Alsa installed, that may be it. I will install, re-test and reply back.

But I do not understand why Gstreamer is not sufficient if it is Qt's back end for Unix.
And how could KDE sound work if Qt could not detect any audio devices. This simply does not make any sense.

SGaist · wrote on 19 Apr 2016, 21:38

Depending on your version of KDE, it's phonon that's used.

nulluse · wrote on 20 Apr 2016, 15:24

So what's the next step?

SGaist · wrote on 20 Apr 2016, 20:37

Start your application with QT_DEBUG_PLUGINS=1 to see what's going on when your application starts.

nulluse · wrote on 21 Apr 2016, 00:35

These lines have something to do with audio:

QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/lib/qt5/plugins/audio" ... // there is no audio directory
QFactoryLoader::QFactoryLoader() checking directory path "/usr/home/leo/NetBeansProjects/OscilloscopeQT/dist/Debug/GNU-Generic/audio" ...
QFactoryLoader::QFactoryLoader() checking directory path "/usr/home/leo/.kde4/lib/kde4/plugins/audio" ... // there is no .kde4/lib
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/lib/kde4/plugins/audio" ... // also no audio directory

Is there a manual on installing the Qt audio plugins under Unix?

SGaist · wrote on 21 Apr 2016, 15:58

That looks strange, you should check with the FreeBSD guys.

nulluse · wrote on 23 Apr 2016, 13:53

According to https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=208987 multimedia audio plugins cannot be installed from the packages under FreeBSD.
They have to be compiled from the ports tree and select the options to build audio plugins and use ALSA or PA:

cd /usr/ports/multimedia/qt5-multimedia
make config 
make deinstall install clean

But still there are no devices recognized after reinstalling with the compiled audio plugins:

 QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/lib/qt5/plugins/audio" ...
 QFactoryLoader::QFactoryLoader() looking at "/usr/local/lib/qt5/plugins/audio/libqtaudio_alsa.so"
Found metadata in lib /usr/local/lib/qt5/plugins/audio/libqtaudio_alsa.so, metadata=
 {
"IID": "org.qt-project.qt.audiosystemfactory/5.0",
"MetaData": {
 "Keys": [
"alsa"
]
 },
 "className": "QAlsaPlugin",
 "debug": false,
"version": 328961
 }


Got keys from plugin meta data ("alsa")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/local/lib/kde4/plugins/audio" ...
 loaded library "/usr/local/lib/qt5/plugins/audio/libqtaudio_alsa.so"
 Device count: 0
Device count: 0

SGaist · wrote on 23 Apr 2016, 20:53

What about PA ?

nulluse · wrote on 27 Apr 2016, 23:50

I am very hesitant to use or rely on PA due to horrible latency and frankly the whole concept of having a sound server where only mic input and speaker output are required sounds outlandish to me.