> Sent: Thursday, January 21, 2016 at 11:07 PM > From: "Glenn Ramsey" <g...@componic.co.nz> > To: interest@qt-project.org > Subject: [Interest] How to get number of channels from QAudioDeviceInfo > > Hi, > > I would like to use the Qt5.x QtMultiMedia to output sound independently on > multi-channel devices such as 5.1 and 7.1 sound cards. However I can't figure > out to tell how many channels a device has. > > From the documentation I guess that QAudioDeviceInfo::supportedChannelCounts > is > the call that I need but that isn't giving the answers that I expect. > > PyQt5 test program (built with Qt 5.5.1 on OSX 10.10.5): > > from PyQt5.QtMultimedia import QAudioDeviceInfo, QAudio, QAudioFormat > > for d in QAudioDeviceInfo.availableDevices(QAudio.AudioOutput): > print d.deviceName(), d.supportedChannelCounts() > f = QAudioFormat(d.preferredFormat()) > f.setChannelCount(6) > print d.isFormatSupported(f) > > Using OSX 10.10.5 on a MacBook Pro I have a 5.1 USB audio card plugged in and > the output from the above program is: > > Built-in Output [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16] > True > USB Audio [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16] > True > > I was expecting some information that would tell me that the built in output > has > 2 channels and that 6 isn't supported and the USB audio has 6 channels. I get > I > similar result on Windows 7. > > What is the right way to query the number of channels on a device?
I am mucking about the OSX multimedia stuff for an unrelated issue. From what I can tell the backends are for reading an writing multimedia from system sources. I don't know if you can count on Qt to be the equivalent of BandCamp, because so much of AVFoundation works differently from other platforms. Qt does a good job of the common stuff, but I think you'll have to go native for low-level details like that. You could extend Qt to those details or just use AVFoundation/CoreAudio directly. Or I could be completely wrong. But that's how Interpret what I've seen so far. _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
