Re: [Alsa-user] Spikes when recording

[Bill U. <un...@ph...>]

Of course it could be that some other program is trying ( and failing) to get
a hold of the sound card at that time but disturbing the system in theprocess.
So to be clear you have some external device (radio, amplifier, whatever)
feeding and audio signal to your sound card. YOu have a program which then
records the line in input to the sournd card to a file.
The other possibility is that the cleaners come in at 2:30 every morning and
plug in their floor polishers which puts spikes on the line.

On Sun, 22 May 2011, li...@la... wrote:

> I would first remove the audio source then short the inputs to the soundcard, run it overnight, and see if the spikes appear. That would determine if the spikes are in the source itself or somehow created in the PC.
>
> Most people don't do automatic updates on their linux boxes, but by chance do you have your update set for 2:30AM?
>
> Is that scanner (radio) audio?
>
> -----Original Message-----
> From: Peter Hoffmann <ph...@pe...>
> Date: Fri, 20 May 2011 16:44:39
> To: <als...@li...>
> Subject: [Alsa-user] Spikes when recording
>
> Hello,
>
> I'm recording audio 24/7 with a delta 1010 sound card and have a
> strange problem:
>
> Every night at 2:30 I get spikes and some inaccurancy within some
> seconds in a one hour length recording. I've upload a screenshot to
> illustrate the problem:
>
> http://img88.imageshack.us/img88/4562/spikesh.png
>
> My .asoundrc
>
> pcm.capt {
>        type dsnoop
>        ipc_key 223456
>        slave {
>                pcm "hw:0,0"
>                rate 8000
>                period_time 0
>                period_size 320
>                channels 12
>                format S32_LE
>        }
> }
>
> pcm.c1 {
>     type plug
>     ttable.0.0 1
>     slave.pcm capt
> }
>
> pcm.c2 {
>     type plug
>     ttable.0.1 1
>     slave.pcm capt
> }
>
> pcm.c3 {
>     type plug
>     ttable.0.2 1
>     slave.pcm capt
> }
>
> pcm.c4 {
>     type plug
>     ttable.0.3 1
>     slave.pcm capt
> }
>
> pcm.c5 {
>     type plug
>     ttable.0.4 1
>     slave.pcm capt
> }
>
> pcm.c6 {
>     type plug
>     ttable.0.5 1
>     slave.pcm capt
> }
>
> pcm.c7 {
>     type plug
>     ttable.0.6 1
>     slave.pcm capt
> }
>
> pcm.c8 {
>     type plug
>     ttable.0.7 1
>     slave.pcm capt
> }
>
> I'm recording with arecord -q -f cd -t wav -d 3600 -c 1 -D c1 out.wav.
>
> Any hints where the problem might be?
>
> Kind Regards,
> Peter Hoffmann
>
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-- 
William G. Unruh   |  Canadian Institute for|     Tel: +1(604)822-3273
Physics&Astronomy  |     Advanced Research  |     Fax: +1(604)822-5324
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