Re: microphone issues - distorted audio

From: Pete Wright via freebsd-multimedia <>
Date: Thu, 30 Sep 2021 03:24:02 UTC

On 9/28/21 11:34 PM, Hans Petter Selasky wrote:
> 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?
> Hi,
> 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.

Hey there HPS - thanks for you hints here.  It ended up I did need to 
use virtual_oss, and after some fiddling on my end I am now able to 
successfully run zoom meetings in firefox with good audio and video quality.


Pete Wright