Rare clicks/crackles when using 44100 (sync problem?)

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Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

I noticed a very strange problem. It happens with jack 1.9.10 and 1.9.12, on different machines with different kernels and Ubuntu versions (14.01, 16.04) and different interfaces: Focusrite Scarlett Solo, 2i2 and 2i4

When using a rate of 48000 the sound is perfect.
When using 44100 I get some clicks, not loud and only about one per minute. It's audible best when playing drones with mellow sounds, e.g. https://soundcloud.com/biser-angelov/se ... fly-effect

But when I use jackd with a dummy device and output via alsa_out then I get no such clicks even with 44100.

I think there is a sync problem with jackd. Unfortunately I have no other brands of USB interfaces available that support 44100.

Any idea how to nail this issue?

Linux – MOTU UltraLite AVB – Qtractor – http://suedwestlicht.saar.de/

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

Arghhh!!!!! Finally someone with the same problem :mrgreen: :mrgreen: :mrgreen:

Here's an old thread:
-> viewtopic.php?t=16577

I never found any solution for this and I observed it at all Linux distributions I tried (Iso images even on different PCs, etc. etc.).
Interface is the Zoom R8, which should work fine with 44.1 khz. I think it's the interface as a different sound card was working fine.
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

But when I use jackd with a dummy device and output via alsa_out then I get no such clicks even with 44100.

I think there is a sync problem with jackd. Unfortunately I have no other brands of USB interfaces available that support 44100.
With jackd it's working? If you tell me what you did I can try to reproduce it here.
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by folderol »

Do you have pulse audio running? If so try disabling it.
The Yoshimi guy {apparently now an 'elderly'}
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

lilith wrote:
But when I use jackd with a dummy device and output via alsa_out then I get no such clicks even with 44100.

I think there is a sync problem with jackd. Unfortunately I have no other brands of USB interfaces available that support 44100.
With jackd it's working? If you tell me what you did I can try to reproduce it here.
Start jackd with -ddummy

Then start alsa_out with the real interface. Use this output in jack then you get no clicks, at least it worked this way yesterday. But I am afraid you get additional latency and maybe – I am not sure – a bit less quality.

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

lilith wrote:Arghhh!!!!! Finally someone with the same problem :mrgreen: :mrgreen: :mrgreen:

Here's an old thread:
-> viewtopic.php?t=16577

I never found any solution for this and I observed it at all Linux distributions I tried (Iso images even on different PCs, etc. etc.).
Interface is the Zoom R8, which should work fine with 44.1 khz. I think it's the interface as a different sound card was working fine.
Which interface doesn't show these clicks? I am willing to buy another one to find out if it is
- an interface problem
- a jackd problem
- an ALSA problem
- a USB driver problem
- ...

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

bluebell wrote:
lilith wrote:Arghhh!!!!! Finally someone with the same problem :mrgreen: :mrgreen: :mrgreen:

Here's an old thread:
-> viewtopic.php?t=16577

I never found any solution for this and I observed it at all Linux distributions I tried (Iso images even on different PCs, etc. etc.).
Interface is the Zoom R8, which should work fine with 44.1 khz. I think it's the interface as a different sound card was working fine.
Which interface doesn't show these clicks? I am willing to buy another one to find out if it is
- an interface problem
- a jackd problem
- an ALSA problem
- a USB driver problem
- ...

I was wrong. I also tested a ESI Dr. Nano and it had the same issues.

You mean staring jack with

Code: Select all

jackd -dummy
? What exactly is this doing (it doesn't work here)?
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

lilith wrote: You mean staring jack with

Code: Select all

jackd -dummy
? What exactly is this doing (it doesn't work here)?
-ddummy

-dalsa uses ALSA backend
-ddummy uses no real soundcard at all. Audio to system:output goes to nirvana

With -ddummy you have a working jackd, so you can start jack programs without having a real interface, e.g.
jackd -ddummy -p256

With alsa_out you can add a soundcard to this jackd, but not as system but as "alsa_out" by default or by the name you assign with -j

Using the soundcard this way seems to bring in some async processing and may be a workaround until we found the cause and have it fixed.

Of course you have to connect your player, e.g. Qtractor or Audacity, to alsa_out:output, not to system:output, to be able to hear something.

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

Thanks, I try to test it later.
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

But then the sound is coming out of my Headphone Jack on the computer not the interface, right?
I tried but it's not working, I think I'm missing something. However I'm pretty sure that it will be fine with the internal soundcard.
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

lilith wrote:But then the sound is coming out of my Headphone Jack on the computer not the interface, right?
I tried but it's not working, I think I'm missing something. However I'm pretty sure that it will be fine with the internal soundcard.
Use in alsa_out the interface that you normaly use with jackd, and use the dummy driver in jackd.

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

I can't believe it. The combination of my laptop in my 2nd flat, Scarlett 2i2 1st gen, Xubuntu 16.04, kernel 4.13.0-38-lowlatency #43-Ubuntu SMP PREEMPT doesn't have the problem.

Have to retry in a few days at home.

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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

I wrote you a message @sequencer. Still not clear :mrgreen:
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by lilith »

I checked again and I get crackling (~0.2 Hz) at 44.1 kHz with Jack, Alsa and Pulseaudio.
With 48.0 kHz I have no problems with Jack and Pulseaudio , but sporadic and less frequent crackling with Alsa.
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Re: Rare clicks/crackles when using 44100 (sync problem?)

Post by bluebell »

The more I try to find out, the worse it gets.

With 48000 the Focusrite Scarletts work perfectly on each of my PCs when used by jackd. With 44100 I have slight clicks about once per minute on 2 of 3 machines.

But wait, there is more:

Notebook with Core i7, Xubuntu 16.04, jackd 1.9.12

jackd with 44100 on Scarlett 2i4
alsa_out with 44100 on Scarlett 2i2
-> works

jackd with 48000 on Scarlett 2i4
alsa_out with 44100 on Scarlett 2i2
-> works (huh?)

jackd with 48000 on Scarlett 2i4
alsa_out with 48000 on Scarlett 2i2
-> noise on Scarlett 2i2
-> kill/restart alsa_out after a Client connects (e.g. Audacity with jack-output) -> works

The same effect as with alsa_out happens with zita-j2a. Whenever a jack-Client connects then alsa_out and zita-j2a can't snchronize anymore, they have to be restarted.

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