Combine 2 USB mono mic audio inputs into L + R of stereo virtual device

Question

I'm running some usability testing sessions where I'm recording a facilitator and a participant while they are testing a mobile app.

I'm using screen recording software on a Windows laptop with a USB webcam to capture video and audio.

I want to record the voices of the two people individually on the left and right channels.

I'm looking for a way to take two USB audio inputs (either from 2 USB mics pointed at each person, or 2 usb webcams), and output them to a new virtual audio device with Left and right channels.

Please note, I could use two basic microphones with 3.5mm jacks and a L/R mono>stereo 3.5mm Y splitter - but ideally would like the flexibility to use the USB mics and webcams I already own.

Answer 1

The correct approach here would be to use a USB mixer/audio-interface with 2 analog mics and recording them to spearate channels.

Combining 2 mics into one input is never recommended (although it may "work" the results are usually subpar).

Using separate USB devices to record simultaneously is tricky to do correctly and is basically unsupported on some platforms.

Answer 2

USB mics are cheap devices without clock sync. Some Firewire soundcards could be daisychained and combined into one larger visible device synchronizing over Firewire. Alas, USB has won the day.

So USB mics will drift: buying more than one of them does not make a whole lot of sense. Basically what you need to do is run one recording application per USB microphone and hope that they don't step on each other's toes. Synchronization is then something to do when you are finished. Your best bet is to clap (hands or clapperboard) at beginning and end of recording and use those distinctive claps for synchronization and if necessary for time stretching.

For basic multichannel work the normal way is to work either with a single soundcard or multiple devices with clocks synched to a common master. Even then you'd not split an actual stereo microphone pair over multiple A/D-converting devices: while clock synchronization eliminates drift, it does not guarantee time-equal sampling and same frequency response.