Solved Qt5.6 Playing .wav file

[Yair BA]

I'm trying, without success, to use QAudio/QMediaPlayer to play .wav file on a board based on Atmel's SAMA5D2. Running Qt multimedia example 'audiooutput', just opens a GUI and print null device error to the serial console.

The error messages are:
If using QAudio - null device found.
If using QMediaPlayer - no service found for - "org.qt-project.qt.mediaplayer".

From the command-line there is no problem to play the same .wav file by using 'aplay' or 'tinyplay' command, so it's not an hardware problem.

Technical details:
buildroot-2016.05
Kernel:4.9
Qt version: 5.6.2
Driver: wm8523
Installed packages (among others): qt5multimedia, gstreamer, alsa

Any suggestions how can I play a .wav file with Qt5? Maybe add phonon package?

Yair

[SGaist]

Hi and welcome to devnet,

You should start your application with the QT_DEBUG_PLUGINS environment variable set to 1. That should show you what happens with the multimedia plugins.

[Yair BA]

I re-built the file system image, this time with Buildroot-2017.02 and Qt version 5.6.2.

I ran, on the target board, the audiooutput example that Qt provides and got a lots of pulseaudio warnings.

Remembering the above QT_DEBUG_PLUGINS hint, I took a look inside the /usr/lib/qt/plugins/audio directory on the target board and found two plugins: libqtmedia_pulse.so and libqtaudio_alsa.so .

Removing the libqtmedia_pulse.so plugin solved the race condition with libqtaudio_alsa.so and solved the problem.

In addition, make sure that alsa-lib builds before qt5multimedia (commit 8d7dd837e5e from mainline Buildroot: "qt5multimedia: conditionally add alsa-lib to dependencies").