Re: [Alsa-user] Spikes when recording
It's conceivable that it's the UPS itself that performs some chore at
the same time everyday. You could try plugging into the mains (without
UPS) during that period of time and see if the problem goes away.
Otherwise, I agree that it could be some sort of once-a-day RFI that may
be difficult to track down.
On 05/21/2011 01:06 AM, Peter Hoffmann wrote:
Hi,
The computer is on a UPS.
The image is just cutout from a whole hour.
I'm recording 24 x 1 hour per day. 23 hours are fine without spikes,
but at always the same time at 2:30 such spikes occur.
Kind Regards,
Peter
On Fri, May 20, 2011 at 5:22 PM, James Shattowwwshad...@gmail.com wrote:
That seems pretty regular at 8 to 10 minute intervals. Do you live
near a subway line? Or other electric mass transit option? Is the
computer on a UPS or power conditioner type supply line? I get a
spike like that when I use a battery box to power an electret mic. If
I turn it on after pressing record. Beyond that, your guess is as
good as mine.
- James
On 5/20/11, Peter Hoffmannp...@peter-hoffmann.com wrote:
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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Re: [Alsa-user] Spikes when recording
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 p...@peter-hoffmann.com
Date: Fri, 20 May 2011 16:44:39
To: alsa-user@lists.sourceforge.net
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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Re: [Alsa-user] Spikes when recording
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...@lazygranch.com 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 p...@peter-hoffmann.com
Date: Fri, 20 May 2011 16:44:39
To: alsa-user@lists.sourceforge.net
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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Re: [Alsa-user] Spikes when recording
That seems pretty regular at 8 to 10 minute intervals. Do you live
near a subway line? Or other electric mass transit option? Is the
computer on a UPS or power conditioner type supply line? I get a
spike like that when I use a battery box to power an electret mic. If
I turn it on after pressing record. Beyond that, your guess is as
good as mine.
- James
On 5/20/11, Peter Hoffmann p...@peter-hoffmann.com wrote:
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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Re: [Alsa-user] Spikes when recording
Le Fri, 20 May 2011 10:22:25 -0500,
James Shatto wwwshad...@gmail.com a écrit :
That seems pretty regular at 8 to 10 minute intervals. Do you live
near a subway line? Or other electric mass transit option? Is the
computer on a UPS or power conditioner type supply line? I get a
spike like that when I use a battery box to power an electret mic. If
I turn it on after pressing record. Beyond that, your guess is as
good as mine.
- James
Such spikes can have 2 origins, from the main or from the air. If they
come from the main, a good quality main filter can help to reduce them,
but sometime it can increase them, so it is no absolute rules here. If
you have external devices connected to the main and to the audio path,
they must have an electrostatic shield between the primary and the
secondary of their main transformers. Separate the audio cables from
the main cables.
Be vary careful with those cheap main adapters (transformers) that
come with a lot of low voltage devices. Many of them are so cheap
that they will have no effect on, or can even increase the high
frequency noise (like such spikes) coming the main. The best solution
here is to replace them with small stabilized supplyes.
You should also pay attention to the earth. For all the audio related
devices, you must have a earth, but only one. For that and if several
devices are earthed, their power cords should be connected directly to
the same earthed plug. (As example, with 3 devices, it will make an Y
with the plug at the centre of the Y). Use good quality extension cords.
If they are too long, they should be completely unwound.
If the spikes comes from the air, it can be very complicated because
the best solution is to eliminate the source. If it is not possible,
only shields will help. And of course a good and unique earth. For the
shields, use good quality shielded audio cables and connectors, prefer
symmetric connections when possible over asymmetric ones.
Ciao,
Dominique
On 5/20/11, Peter Hoffmann p...@peter-hoffmann.com wrote:
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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next-generation tools to help Windows* and Linux* C/C++ and Fortran
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