[Interest] I am having problems reading multichannel data from usb soundboards using QAudioInput and QAudioInfo

val and leslie vveirs at coloradocollege.edu
Thu Aug 15 22:08:12 CEST 2013


I am brand new to this mailing list so bear with me as I learn how you 

I have found that the Audio Input example that comes with QT 5.0.1 
running under Ubuntu 12.03 and 13.04 does not return correct 
multichannel data. I modified the example for two channels and I find 
that data from channel 1 shows up in channel 1 and also in channel 2. I 
have checked this with two different USB soundboards (Griffen iMic and 
Lexicon Omega). I also have checked that the Ubuntu ALSA driver works 
for the USB soundboard (arecord -v -c 2 -f cd -t wav -D hw:CARD=system 
test1.wav records a proper two channel file with the proper channel 

So, it seems to me that AudioInput or AudioInfo is not working properly.
If I interrogate the devices via
AudioInfo via foreach(const QAudioDeviceInfo &deviceInfo, 
qDebug() << “Device name: “ << deviceInfo.deviceName();

I find that the iMic shows up only as mono:
Device name: 

Interestingly, the Lexicon which is a 4 channel A/D shows up as stereo
Device name: 

When reading 4 channel data with a signal in channel 1 and zero signal 
on the other channels, the signal comes in on channel 1 but various 
seemingly random portions show up in the other channels.

I wonder if others have found a solution to getting multichannel audio 
data into Qt using QAudioInput?

Thanks for any suggestions.

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