Visualise audio waveform from video local file using Qmedia player - c++

Question

I try without success to plot waveform using qMediaPlayer and QaudioProbe object to get the QAudioBuffer but it's always fails when I try:
player = new QMediaPlayer;
audio = new QAudioProbe ;
QAudioRecorder *recorder = new QAudioRecorder();
if (audio->setSource(player))
{
// Probing succeeded, audioProbe->isValid() should be true.
std::cout << "probing succed"<< std::endl;
connect(audio, SIGNAL(audioBufferProbed(QAudioBuffer)), this,
SLOT(processBuffer(QAudioBuffer)));
}
this line:
if (audio->setSource(player))
always return false!
when I replace QMediaPlayer by QAudioRecorder the setSource function works well.
do you have any idea to do that, or m'I in a wrong direction?
otherwise is there other way to split audio from video file.
thanks a lot

Answer 1

From the documentation on QMediaPlayer, I would gather that since the property audioAvailable can change, the default is that audioAvailable is false.
If there is no audio available, the documentation of setSource states that
"If the media object does not support monitoring audio, this function
will return false."
Try loading an actual piece of media, that has audio available (check that first) before trying to set the source