State of Jack as a full pulsaudio replacement

Luke Kuhn lukekuhn at hotmail.com
Sun May 6 18:01:06 UTC 2012


I have had trouble getting pulseaudio to stay turned off and use no resources when nothing is connected to it and anything is using alsa directly. When I did my original Lucid/Pentium III experiments in 2010, Pulseaudio would use 15% of that very limied CPU with mplayer playing a vga resolution vidio using mpeg-4 video codec in mp4 container or a flash video of same dimensions. All of that CPU, not 85% of it, was needed to keep up. Configuring mplayer to use alsa or (in those days) oss did not change anything, pulseaudio still ran and still used that 15%.  Killing pulseaudio just caused it to respawn. The only way I ever found to reliably turn it on and off was a pair of scripts to change the permissions of the binary to allow or disallow execution, and to kill the process in the disallow case.

This turned out to be important for working with AVCHD video in kdenlive on an AMD Phenom II x4 workstation, a hell of a lot more machine than a Pentium III. In that case, pulseaudio worked fine in kdenlive(after the usual kdenlive hacks...)-until I asked it to work with the AVCHD files. Then it used too much resources, as once again, that camera I use produces a very processor-intensive codec. Thus, I cannot use pulsaudio in th video editing workstations because the most important program, kdenlive, stutters when loaded that heavily with pulseaudio in use. The sound cards in those machine work fine with just alsa, and kdenlive then keeps up except in transitions. The only thing that ever made it keep up in transitions was AMD bulldozer, an nvidia GTS 450, and the open source nouveau driver(NOT the binary blob!)

Since every pulseaudio update meant having to re-run the disable script, I threw in the towel and removed it from both desktops.

The Intel Atom laptops with the newer N450 chips had video playback issues in flash on Liveleak, and less so on mplayer-not enough memory bandwidth. Solutions turned out to be using a non-compositing desktop (don't run a unity/gnome-shell session) and to disable or remove pulseaudio-again. As a result, I cannot use pulseaudio on the laptop, leaving no machines to routinely monitor it's development and any improvements that might fix this down the line.

Best fix might be a better control for pulseaudio, one that can turn it on or off, and it will stay on or stay off and not respawn. This would have to be combined with a volume control that works both with and without pulseaudio running.  I agree that for any kind of maximum performace workstation, as well as for video playback with limited resources, people are going to have to set up sound for their particular circumstances.  Possibly some kind of GUI control for US that would control jack, pulse, and alsa configurations from one screen? Maybe bring it up automatically at first run or in installation?

> Message: 3
> Date: Sat, 5 May 2012 13:32:22 -0700
> From: "Len Ovens" <len at ovenwerks.net>
> To: "Ubuntu Studio Development & Technical Discussion"
> 	<ubuntu-studio-devel at lists.ubuntu.com>
> Subject: Re: State of Jack as a full pulsaudio replacement
> Message-ID:
> 	<6e439a9c89ada09487e8fa1f3c25c540.squirrel at ssl.ovenwerks.net>
> Content-Type: text/plain;charset=iso-8859-1
> 
> 
> On Sat, May 5, 2012 3:39 am, Kaj Ailomaa wrote:
> 
> 
> > I think the main problem is not pulseaudio itself anymore. It would be
> > nice to have a simple way to turn it off. I think it's more about
> > desktop control than the server itself that is the issue these days.
> 
> I have found that turning pulse off is not needed. Pulse is quite happy to
> sit doing nothing taking up minimal resources if the PA-jack bridge module
> is unloaded. If PA is not bridged to jack then it is not forced to run at
> whatever latency jack is running at.
> 
> PA-jack problem two, more than one audio card. Turn off the card not being
> used in pulse... makes a big difference with things like stuttering.
> 
> There is no perfect solution yet. (maybe never) But just as in a hardware
> studio where patches have to be changed depending on use... care needs to
> be taken to set up jack and pulse in the virtual studio too. It's not
> auto, but this is a good thing, it allows me to get around problems that
> an auto mode might not.
> 
> Pulse is what lots of apps are set up for. It is easier to change the
> routing on one piece of SW (pulse) than to reconfigure every pulse client
> to hit jack. It is a lot less work to just ship the same multimedia as
> other ubuntu distros. I don't like PA much either, but I use it anyway. I
> just have to be a little more aware of how it works than the average
> desktop user. As someone interesting in a low latency kernel, I've already
> taken one step in that direction and shown an interest in learning more.
> 
> US is for those who have a desire to get more out of their equipment than
> the average desktop user, if it is tuning the audio/midi setup or
> calibrating a monitor. Time for more documentation. It looks like we need
> a page just on setting up sound..
> 
> -- 
> Len Ovens
> www.OvenWerks.net
> 
> 
> 
 		 	   		  
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