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Drasica
Apprentice
Joined: 16 Apr 2006
Posts: 181
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 Posted: Mon Feb 21, 2011 8:35 pm Post subject: jack xrun reduction tips |
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I've been getting occasional xruns upon seemingly mundane tasks (e.g. resizing my firefox window).
It's pretty annoying!
Here are my settings (from reading off the qjackctl setup panel):
Driver: firewire
Realtime: yes
No Memory Lock: yes
Unlock Memory: no
Priority: default
Frames/period:1024
sample rate:44100
periods/buffer:3
Port max: 256
Timeout: 500msec
Start delay: 2sec
Interface: default
Audio: duplex
Input channels, output channels, input/output latency: all default
Latency: 69.7 msec
Thanks for any suggestions/insight |
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key
n00b
Joined: 11 Nov 2005
Posts: 5
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| Posted: Wed Mar 02, 2011 8:51 am Post subject: |
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What's the output in the qjackctl messages window?
Also, read this wiki. In particular, check out the kernel configuration and RLIMITS sections.
Hope this helps |
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aCOSwt
Bodhisattva
Joined: 19 Oct 2007
Posts: 2537
Location: Hilbert space
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| Posted: Wed Mar 02, 2011 9:26 am Post subject: |
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Well well... I believe you know this well... there is no secret for reducing the number of xruns :
0/ Configure your kernel correctly for realtime
1/ Increase nb frames / period
2/ Increase nb periods / buffer
3/ Decrease sampling rate
4/ Reduce the number of Jack clients
5/ Close processes unrelated with sound
A/ From what I see with your datas, you already get a rather huge latency  => You cannot reasonably act on 1/ and 2/
B/ You cannot act on 3/ either, as your sampling rate is the minimum acceptable
=>
C/ Tell us more about your kernel version & configuration (maybe you could pastebin it or, if you know well the important options just post only the relevant parts here) BTW I hope you did not opt for activating the famous self-claimed magical 200 lines or so patch...  )
D/ Which Jack clients are you running concurrently ?
E/ If you are in a real need for an xrun free sound output, why the hell are you doing "mundane tasks" concurrently ? (Particularily playing with windows with things such as compositing activated...)
F/ By the way... Do tell us that you are not cascading several sound servers (phonon, pulseaudio or other thingies of the thing... )
BTW : Which Jack are you running ? Legacy or Jack2 ? |
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Drasica
Apprentice
Joined: 16 Apr 2006
Posts: 181
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| Posted: Sun Mar 27, 2011 5:32 pm Post subject: |
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| aCOSwt wrote: |
C/ Tell us more about your kernel version & configuration (maybe you could pastebin it or, if you know well the important options just post only the relevant parts here) BTW I hope you did not opt for activating the famous self-claimed magical 200 lines or so patch... )
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I'm using 2.6.36-r5 on amd64 arch. Here is my kernel config: http://web.mit.edu/~cjoseph/Public/config
D/ Which Jack clients are you running concurrently ?
Usually qsynth and the Audacious (xmms) jack plugin. Occasionally qsynth and ardour.
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E/ If you are in a real need for an xrun free sound output, why the hell are you doing "mundane tasks" concurrently ? (Particularily playing with windows with things such as compositing activated...)
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I just bought a new machine, and it seems to be incredibly electrically noisy. As in, media is unberable to listen to. As a substitute, I pipe my media through the firewire soundboard.
This "everyday" usage is unusual, but I do have a fairly powerful machine, and I have a pretty lightweight desktop enviro (xfce)
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F/ By the way... Do tell us that you are not cascading several sound servers (phonon, pulseaudio or other thingies of the thing... )
BTW : Which Jack are you running ? Legacy or Jack2 ? |
F: No
And I am using jack legacy 0.118 |
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aCOSwt
Bodhisattva
Joined: 19 Oct 2007
Posts: 2537
Location: Hilbert space
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| Posted: Wed Mar 30, 2011 6:54 am Post subject: |
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| Drasica wrote: | | I just bought a new machine, and it seems to be incredibly electrically noisy. |
Would this simply be because of a bad ground ?
Do indeed ensure this first. Working with DAC / ADC without a good link to the ground has always been a bad idea. |
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Drasica
Apprentice
Joined: 16 Apr 2006
Posts: 181
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| Posted: Wed Mar 30, 2011 7:03 am Post subject: |
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It is grounded well--if it were not, the hum would begin as soon as the PC is turned on, no?
It is linked to a driver, I think, because if I insert a livecd the hum does not begin until the end of the boot process--when coldplug loads all the drivers.
I'm working on figuring out exactly which driver(s) cause this, but a reduction on xruns in the meantime would be nice, because I do occasionally do hobby audio work.
As an update, I upgraded the CPU/RAM to a Quadcore Phenom and 8G. It no longer xruns when I'm resizing windows or something, but I still get a lot...even when the machine is idle and I'm just sending music over it. Because the resources are plentiful, it seems like I may need to tweak some configs to reduce xruns. |
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aCOSwt
Bodhisattva
Joined: 19 Oct 2007
Posts: 2537
Location: Hilbert space
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| Posted: Wed Mar 30, 2011 9:33 am Post subject: |
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| Drasica wrote: | | it seems like I may need to tweak some configs to reduce xruns. |
Well... I believe that it is something more important than tweaking.
As a matter of fact, my audio workstation is about half powerful as yours and I can run concurrently three to four times more jack's clients with a third of your theoretical latency without experimenting Xruns.
And this without any particular tweak.
Being said that I am running gentoo-sources 2.6.34 + Intel and do not know exactly what should be done under 2.6.36 / AMD, These are the observations I made with regards to your kernel conf.
1/ CONFIG_SLUB_DEBUG=y : I cannot tell the exact impact but I believe that debugging and performances in this area of concern are in exclusive or.
2/ CONFIG_DEFAULT_CFQ=y / CONFIG_DEFAULT_IOSCHED="cfq" : I prefer the noop one. Being said that max priority is given to audio tasks, I believe that their I/O requests have to be made straight away. In an audio workstation we are at the opposite of looking to be fair !
3/ CONFIG_NO_HZ is not set : I would definitely set this one
Could you also tell
- if your Xruns are coming by flows or regularily one per one ?
- if you experiment the same with your on board audio system ?
Have you tested with bfs ? |
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key
n00b
Joined: 11 Nov 2005
Posts: 5
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| Posted: Fri Apr 01, 2011 8:02 am Post subject: |
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| aCOSwt wrote: | | Drasica wrote: | | it seems like I may need to tweak some configs to reduce xruns. |
Well... I believe that it is something more important than tweaking.
As a matter of fact, my audio workstation is about half powerful as yours and I can run concurrently three to four times more jack's clients with a third of your theoretical latency without experimenting Xruns.
And this without any particular tweak.
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+1.. My not-particularly-powerful laptop (intel i3) is able to cope with jack running in full duplex, almost without xruns. I work under kde4, but i use the rt-sources kernel from the pro-audio overlay.
About the noise: Can you exclude the possibility of a faulty sound interface? Maybe the noise is always present, but the output of the interface is zeroed until the driver is loaded? (wild guessing)
hope this helps |
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