@SGaist, the application being developed supports an earlier/lower version of Windows while the IAudioClientDuckingControl requirest at least Windows 10 build 20348 which is a later one. But I have already tested the interface mentioned above and it doesn't have any effect.

@SGaist That is correct. The same application tested on different Windows machines presents exactly the same behavior.

@Anthony-Abboud for the crackling sound issue, I could fix my issues with https://codereview.qt-project.org/c/qt/qtmultimedia/+/503818 and this is such a generic error that I expect that you hit the same problem.
For the missing sound output, the following changed helped me https://codereview.qt-project.org/c/qt/qtmultimedia/+/503819 . Yet for that I am not sure yet if it is a proper solution or just a workaround.

Hi,

You can start from the sample in the class documentation and change the sample size to 16.

The problem was in the Windows firewall. I still don't understand why this was affecting the sound, but disabling the firewall did the trick.

@SGaist Hey so the reference problem is solved. Seems like the file can be opened, the player works but there is no sound :-/. I'll probably open another thread for this issue. Thanks for the help again!
EDIT: Or maybe it's working :D. On other devices I got a report that the sound is OK. Will investigate that further!

@iamRahul I figured it out. We need to specify full location path till the file, and specify file type in format. Then it worked for me.

if(audioPlaylist.save("file:///C:/MyMusicPlayer/Playlists/global_playlist.m3u","m3u")) { console.log("Playlist Saved") }

Adding the filename global_playlist.m3u and format m3u made it working for me.

The Linux backend uses GStreamer. You can take a look at the code and maybe modify it for your purpose.

It seems remarkable to me that the QMediaPlayer can know whether I'm playing back audio with 1, 2, or more channels, but I cannot get that information from it, but I guess that's just the way it is? It seems like some people can get this to work, and others can't, so I wonder if this is another issue of platform differences? (For reference, this is playback either via a wired connection to an MFi device, or directly on an iPad/iPhone, so iOS under the hood.)

Anyway, I've given up on displaying mono/stereo channel information in our implementation. (The player will fail to play back audio with three or more channels, so I can at least flag that. It'd be nice to label, but it's not required.) I'll report a bug if I get the time at some point.

Thank you for your help, I've probably identified the problem - one of the input parameters was a char (8 bit). I've tried to fix it using the following code to reformat it so that it can be used properly for 16 bit but I keep getting the same problem

/* Function with char as one of the parameters - qint64 XYSeriesIODevice::writeData(const char *data, qint64 maxSize) - same as in the Qt audio example**/ int bitsPerSample = 16; int bytesPerSample = (bitsPerSample / BITS_IN_BYTE); int signalLength = (strlen(data) ) / numChannels / bytesPerSample; short* signal = (short*)malloc(sizeof(short) * signalLength); for(int i = 0; i < signalLength; i++){ int index = i * numChannels * bytesPerSample; memcpy(&signal[i], &data[index], sizeof(short)); }

Any suggestions?

hi
well you can hook up the AUDIO positionchanged
signal to your own method (slot)
using connect.
http://doc.qt.io//qt-5/signalsandslots.html

so it will directly call your method when it changes.

https://drive.google.com/file/d/1SHw3k6gY9pz8cL7skhDUPUf2NrwF4xeE/view

@Cleiton-Bueno thanks for your suggestion. I have disabled audio in my kernel completely now. Now I get the message CameraBin warning: "Could not open audio device for recording." which shows, that I really removed audio support.
Unfortunately, this still doesn't solve my basic issue, which is a extremely sluggish video output when the videoRecorder property is enabled in the Camera. That means, the audio encoding was not causing this problem at all.

Thx, Jens

Hi and welcome to devnet,

You should check what your device support, QAudioDeviceInfo gives you all the various channel counts, sample sizes etc. that are supported by the device you want to use.

The please first update to 5.9.1

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").