I have a Creative Labs Sounds Blaster Play (SB1140) USB Sound card. When I plug it into either a Windows or Mac computer, I am able to record line level audio through the Mic jack - clean and clear.When I use the USB device on Linux (Debian Noobs RPi) with the SAME audio source - I get HORRIBLE high level screaming noise - with a very quiet audio signal.How do I get my linux device to record the same clear audio that the Mac and Win boxes have no trouble doing with the same device? Is there some amixer setting I need to toggle etc etc?My GUESS is that the Mac and Windows boxes somehow realise that the input is line level, and toggle some setting in the SB card to handle that - but I need to do that manually on Linux. I would really hate to have to add circuitry to solve something that can be done in software...Currently this is my command line to monitor the SB mic input:ffmpeg -ac 1 -f alsa -i hw:1,0 -ac 2 -f alsa front:CARD=U0x41e0x30d3Addiontal Note: On the linux computer, if I plug in a Mic rather than line level input (into the Mic input) I also get clean audio. So the issue is specifically that line level input works on Win/OSX but not linux.Note: I have discovered that my line input is actually balanced (single channnel + polarity and - polarity). However this doesnt change the fact that Pi sounds horrible - mac/win work.UPDATE:The more I read about this, the more that I am thinking there is an amixer command to tell the sound card to treat the incoming signal as a balanced input. When I use amixer contents it does not list anything that mentions balanced/differential sources - so I am guessing that I need a device specific driver, rather than the generic usb-snd driver to be able to access any potential extended functionality?
Treat USB Sound card mic input as line input
audio;recording