2 Nov
2003
2 Nov
'03
11 a.m.
Hello all !
What could I do about the following problem ?
I have an M-audio delta66 + omni I/O (preamp/breakout box). This card
has an onboard digital mixer that allows hardware monitoring of inputs.
- when setting this mixer to directly route a HW input to a PCM output,
the sound is perfectly fine. The signal goes through both an A/D and a
D/A conversion before reaching my ears. I suppose that if I had a ground
loop problem (or other analog noise source), I would hear it with such a
setup.
- now, when using jackd to route (with no jack client in between) the
alsa capture port associated with the HW input to a playback port, the
sound is full of horrible "blips".
I use :
- IRQ #10 for the delta66 (I even disabled the USB controller of the
motherboard which used IRQ#11, with no better results).
- a patched for LL 2.4.19 kernel, ext2 filesystems and hdparm'ed HDs.
- alsa 0.9.6
- a tmpfs work directory for jackd that I start with '-R' as root.
How could I isolate the source of this very annoying problem ?
Is there a way to route an input to an output through ALSA only without
using jackd (and the hw mixer too of course) ? Maybe that would help
tracking down the culprit ...
I'd appreciate any hint on this. Thanks a lot !
--
David
2 Nov
2 Nov
12:11 p.m.
I'm not sure I'm following this. How have you got envy24control set
up? Are H/W Out 1/2 set to PCM Out 1/2 or Digital Mix L/R? I've had a
problem that sounds similar when using the Digital Mix L/R combo. I
found that muting all of the channels except PCM Out 1/2 cleared it up.
I think it was that PCM Out 1/2 were being overdriven.
Jan
On Sun, 2003-11-02 at 09:20, David wrote:
Hello all !
What could I do about the following problem ?
I have an M-audio delta66 + omni I/O (preamp/breakout box). This card
has an onboard digital mixer that allows hardware monitoring of inputs.
- when setting this mixer to directly route a HW input to a PCM output,
the sound is perfectly fine. The signal goes through both an A/D and a
D/A conversion before reaching my ears. I suppose that if I had a ground
loop problem (or other analog noise source), I would hear it with such a
setup.
- now, when using jackd to route (with no jack client in between) the
alsa capture port associated with the HW input to a playback port, the
sound is full of horrible "blips".
I use :
- IRQ #10 for the delta66 (I even disabled the USB controller of the
motherboard which used IRQ#11, with no better results).
- a patched for LL 2.4.19 kernel, ext2 filesystems and hdparm'ed HDs.
- alsa 0.9.6
- a tmpfs work directory for jackd that I start with '-R' as root.
How could I isolate the source of this very annoying problem ?
Is there a way to route an input to an output through ALSA only without
using jackd (and the hw mixer too of course) ? Maybe that would help
tracking down the culprit ...
I'd appreciate any hint on this. Thanks a lot !
--
David
1:47 p.m.
On 02 Nov 2003 09:48:44 -0600
Jan Depner <eviltwin69(a)cableone.net> wrote:
I'm not sure I'm following this. How have you
got envy24control set
up? Are H/W Out 1/2 set to PCM Out 1/2 or Digital Mix L/R? I've had
a problem that sounds similar when using the Digital Mix L/R combo. I
found that muting all of the channels except PCM Out 1/2 cleared it
up. I think it was that PCM Out 1/2 were being overdriven.
I hear no noise when I set H/W Out 1/2 the right H/W In (straight input
monitoring) or when I set H/W Out 1/2 the Digital Mixer (after unmuting
and raising the level of the input channel of course).
Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect using
jackd the alsa capture port (that map to a H/W In) to the alsa playback
port 1/2 (that maps to PCM Out 1/2).
Is this a better description ?
I've just upgraded my kernel to 2.4.22+ll and alsa to 0.9.8 but this did
not change the situation.
Jan
Thanks for answering.
--
David
2:18 p.m.
On Sun, 2 Nov 2003 19:07:39 +0100
David <dplist(a)free.fr> wrote:
On 02 Nov 2003 09:48:44 -0600
Jan Depner <eviltwin69(a)cableone.net> wrote:
David, how exactly dows this mapping take place? Via a command line?
A jack patchbay? Routing in a particular program? or with the
envy24control GUI? Detailing the steps you take to set this up may
prove helpful.
I recall having this happen when I had the Omni (long since upgraded
to a Delta 1010). I think there was some sort of monitoring or source
button I had to push on the Onmi box to stop this. The noise, if it's
what I'm thinking of, is the digital equivalent of a feedback loop.
--
======================================================================
Joe Hartley - UNIX/network Consultant - jh(a)brainiac.com
Without deviation from the norm, "progress" is not possible. - FZappa
I'm not sure I'm following this. How
have you got envy24control set up?
Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect using
jackd the alsa capture port (that map to a H/W In) to the alsa playback
port 1/2 (that maps to PCM Out 1/2).
2:49 p.m.
On Sun, 2 Nov 2003 13:18:12 -0500
Joe Hartley <jh(a)brainiac.com> wrote:
On Sun, 2 Nov 2003 19:07:39 +0100
David <dplist(a)free.fr> wrote:
By default, jackd maps its "alsa_pcm:capture_1" port to the "H/W In 1"
input of the soundcard and its "alsa_pcm:playback_1" port to
the "PCM Out 1" of the soundcard.
I connected these two jack ports using qjackconnect, I guess I could do
the same with jack_connect.
With envy24control's "Patchbay/Router", I chose "PCM Out 1" to be
heard on "H/W Out1" so that I can hear what jackd is spitting in
"alsa_pcm:playback_1".
I this a little bit clearer ? Sorry for being confusing.
On 02 Nov 2003 09:48:44 -0600
Jan Depner <eviltwin69(a)cableone.net> wrote:
David, how exactly dows this mapping take place? Via a command line?
A jack patchbay? Routing in a particular program? or with the
envy24control GUI? Detailing the steps you take to set this up may
prove helpful. I'm not sure I'm following this. How
have you got envy24control
set up?
Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect
using jackd the alsa capture port (that map to a H/W In) to the alsa
playback port 1/2 (that maps to PCM Out 1/2). I recall having this happen when I had the Omni (long
since upgraded
to a Delta 1010). I think there was some sort of monitoring or source
button I had to push on the Onmi box to stop this. The noise, if it's
what I'm thinking of, is the digital equivalent of a feedback loop.
On the Omni itself ? I don't think I have such a button.
--
======================================================================
Joe Hartley - UNIX/network Consultant - jh(a)brainiac.com
Without deviation from the norm, "progress" is not possible. - FZappa
Thanks.
--
David
3:54 p.m.
On Sun, 2003-11-02 at 12:07, David wrote:
Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect using
jackd the alsa capture port (that map to a H/W In) to the alsa playback
port 1/2 (that maps to PCM Out 1/2).
Is this a better description ?
Yes. I believe Joe is correct - it sounds like a feedback loop to me.
Why are you connecting these? If you want to monitor in real time just
set HW Out 1/2 to Digital Mix L/R.
Jan
4:28 p.m.
On 02 Nov 2003 13:32:19 -0600
Jan Depner <eviltwin69(a)cableone.net> wrote:
On Sun, 2003-11-02 at 12:07, David wrote:
I wanted to play a guitar through jack-rack and I heard this noise. Did
it come from jack-rack, a ladspa plugin, jackd, alsa, the soundcard ?
This is why I tried to isolate the problem, ending with a very simple
setup : jackd connects the input channel to the output channel PCM Out 1
assigned to H/W Out 1 (with the "PatchBay/Router" in envy24control). I
still get the noise.
I don't have this problem when doing true hardware monitoring of the
input : be it by assigning H/W In 1 to H/W Out 1 (with the
"Pathbay/Router") or by assigning Digital Mixer L to H/W Out 1 (with
the"Patchbay/Router") and unmuting/raising the slider of channel H/W
In 1 with the "Monitor Mixer" pane in envy24control.
Bad noise comes when I set H/W Out 1/2 to PCM Out 1/2 and connect
using jackd the alsa capture port (that map to a H/W In) to the alsa
playback port 1/2 (that maps to PCM Out 1/2).
Is this a better description ?
Yes. I believe Joe is correct - it sounds like a feedback loop
to me. Why are you connecting these? If you want to monitor in
real time just set HW Out 1/2 to Digital Mix L/R. Jan
Thanks.
--
David
5:16 p.m.
On Sun, 2 Nov 2003 21:48:58 +0100
David <dplist(a)free.fr> wrote:
I wanted to play a guitar through jack-rack and I
heard this noise. Did
it come from jack-rack, a ladspa plugin, jackd, alsa, the soundcard ?
This is why I tried to isolate the problem, ending with a very simple
setup : jackd connects the input channel to the output channel PCM Out 1
assigned to H/W Out 1 (with the "PatchBay/Router" in envy24control). I
still get the noise.
I don't have this problem when doing true hardware monitoring of the
input : be it by assigning H/W In 1 to H/W Out 1 (with the
"Pathbay/Router") or by assigning Digital Mixer L to H/W Out 1 (with
the"Patchbay/Router") and unmuting/raising the slider of channel H/W
In 1 with the "Monitor Mixer" pane in envy24control.
A couple of suggestions for narrowing the problem down further:
1. Record something (ideally something easy to see and hear problems with - such as an
oscillator) via alsa, without jack
2. Record the same signal with jack
3. Examine the waveforms visually
If the recorded waveforms look garbled:
4. Post a small fragment or two on a web server
5. Pass along the URL so we have something more precise than "the
sound is full of horrible "blips"." ;)
If the recorded waveforms look okay:
4. Play the recordings via alsa
5. Play the recordings via jack
This should help identify where the problem is.
|)
|)enji
7694
days inactive
7694
days old
linux-audio-user@lists.linuxaudio.org
7 comments
4 participants
participants (4)
-
Benjamin Flaming -
David -
Jan Depner -
Joe Hartley