[CentOS] Re: recording sound: how 2 control recording level?

Sat Apr 28 17:34:14 UTC 2007
John R Pierce <pierce at hogranch.com>

> Maybe it is your soundcard. Not all soundcards work 100% with linux. and I
> think you would have to have DMA working with it to get good recordings.
> Playing directly and recording to storage take different amounts of processor
> time. Also, are you recording to a line in port on the card or a mic port.
> Line in and mic ports have different attenuation and might need a matching
> transformer or some other sort of level control. That is why higher end cards
> have both a mic and line in port.

feeding a Line Out to a Mic In just needs attentuator resistors, not a 
matching transformer.   you can buy a mini-stereo-phone to 
mini-stereo-phone patch cable with these attenuators built in, designed 
to allow you to feed the line out from a CD player into a walkman style 
tape deck's mic input.   The usual attenuator is 100K ohms in series, 
and 10k ohms in parallel .   Note recording from a Mic Input will likely 
be noisier.