How to specify the channel number of USB audio interface.

tidbit

I want to create a program to import audio signals from USB audio interface.
I've read the Qt specifications,
but I can't find a function to specify the channel number to be recognized.
Is there a function to specify a channel other than channel number 1 in Qt?

SGaist

Hi and welcome to devnet,

Which OS are you on ?
How is your card seen by the system ?
What are you using to do the capture ?
How does Qt get when you enumerate the devices from it ?

tidbit

Thanks for the reply.
I am using Windows 10 and MacOS 10.14.
On the USB audio interface I have, the "QAudioDeviceInfo" returns the following.

supportedByteOrder : [LittleEndian][BigEndian].
supportedSampleType : [SignedInt][UnSignedInt][Float].
supportedSampleRates : [128000][32000][48000][64000][192000][96000][88200][44100][176400]]
supportedChannelCounts : [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]
supportedSampleSizes : [8][16][24][32][64].
supportedCodecs : [audio/pcm]

However, this audio interface is originally a 64-channel product,
so I think the "supportedChannelCounts" number is wrong.

No matter how I set it, only the input of channel number 1 was recognized.
Does this mean that Qt can't properly recognize USB audio interfaces with more than 16 channels?
I would like Qt to recognize a number other than channel number 1 and run the program.

SGaist

Looks like the kind of hardware that is out of league for QtMultimedia.

Depending on what you want to do next, I think that PortAudio is worth checking.

tidbit

@SGaist
So that's what it was after all.
I had expected that since there was no setting for it, but...

Thank you very much for the good information!
I'll check out PortAudio.

DrSnowLabs

@tidbit [a few years later] ... still get the same issue. no matter what device I chose, the max number of channels reported is always 16... did you have any luck with PortAudio?

DrSnowLabs

https://code.qt.io/cgit/qt/qtmultimedia.git/tree/src/multimedia/darwin/qdarwinaudiodevice.mm#n36

Hardcoded to 16 channels 96k... ?

SGaist

@DrSnowLabs Sounds like there might be something to improve :-)