Re: microphone issues - distorted audio

From: Hans Petter Selasky <>
Date: Wed, 29 Sep 2021 06:34:24 UTC
On 9/29/21 5:56 AM, Pete Wright via freebsd-multimedia wrote:
> hello,
> i have the following configuration for my audio system on current/amd64:
> $ cat /dev/sndstat
> Installed devices:
> pcm0: <ATI R6xx (HDMI)> (play)
> pcm1: <ATI R6xx (HDMI)> (play)
> pcm2: <ATI R6xx (HDMI)> (play)
> pcm3: <ATI R6xx (HDMI)> (play)
> pcm4: <ATI R6xx (HDMI)> (play)
> pcm5: <Realtek ALC892 (Rear Analog 7.1/2.0)> (play/rec) default
> pcm6: <Realtek ALC892 (Front Analog)> (play/rec)
> pcm7: <USB audio> (rec)
> No devices installed from userspace.
> I am having issues with recording audio, using both my Realtek ALC892 as 
> well as via my USB webcam (pcm7).  in both cases the audio sounds very 
> distorted, if i talk into the microphone my voice is very distorted 
> almost mechanical sound.  it is interesting that i get the same 
> experience with both my ALC892 and USB audio device.  I've also tried 
> adjusting various mixer settings, and adjusted my input gain to no 
> avail.  I'm kind of at a loss here to figure out what my next debugging 
> steps should be - any pointers?


In what what is the audio distorted?

Did you check using "mixer" that the levels are appropriate?

If you want to use one device for recording and another for playback, 
installing a audio daemon like virtual_oss is recommended. It might 
simply be a sample rate mismatch.

Regarding the USB webcam, make sure you device is connected directly to 
a port on the computer.

If you install "sox", there is "rec" and "play" for simple testing. An 
environment variable can override the audio device used.