Linked by Thom Holwerda on Thu 8th Oct 2009 19:09 UTC, submitted by MadMAtt
Linux Lennart Poettering, creator of open source sound server PulseAudio, was recently interviewed at this year's Linux Plumbers Conference. In this Q&A he details the latest PulseAudio developments and addresses some of PA's critics. Thanks to PulseAudio, the Linux audio experience is becoming more context-aware. For example, if a video is running in one application the system should now automatically reduce the volume of everything else and increase it when the video is finished.
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JACK != PulseAudio
by Tuxie on Fri 9th Oct 2009 08:22 UTC in reply to "RE: Comment by supercompman"
Tuxie
Member since:
2009-04-22

Maybe because most people who use JACK use a custom compiled realtime-kernel and carefully selected, well supported audio hardware? Also, JACK is used with apps that have been carefully written to support it.

JACK has a very different feature set from PulseAudio. The overlap is pretty small. It's possible that they will "grow together" at one time in the future but that's not even on the roadmap today.

With PulseAudio, people use it with all kinds of cheap hardware with crappy ALSA drivers, badly coded, closed source software with all kinds of ugly hacks. When ANYTHING in the chain doesn't work properly, be it a stupid kernel configuration like Ubuntu's default one, missing features of the ALSA drivers, badly coded applications that does all kinds of tricks to bypass the proper, well emulated ALSA APIs, they blame it on PulseAudio. *sigh*

Reply Parent Score: 2

segedunum Member since:
2005-07-06

Maybe because most people who use JACK use a custom compiled realtime-kernel...

No. That's rubbish. JACK uses real-time scheduling privileges, but doesn't need a specific real-time kernel to work well at all. All distributions have packaged JACK. I've never seen it need the kind of handholding that is being quoted there. The figures of several hundred milliseconds of latency for various kernels, I cannot see where on Earth he has got those from.

...and carefully selected, well supported audio hardware?

No it doesn't. That's rubbish as well. It uses ALSA for it's I/O drivers.

Also, JACK is used with apps that have been carefully written to support it.

Yer. It has a proper set of interfaces that Pulse still doesn't have. Emulating ALSA, again, should have been out of the question.

JACK has a very different feature set from PulseAudio. The overlap is pretty small.

People use that as an excuse, but you can make a direct comparison between the kind of latency PulseAudio adds versus JACK to achieve the same things - in particular, software mixing. No matter what you do, a sound server will always add latency but what you see coming out of Pulse is ridiculous. If you're playing a game, turn the damn thing off.

In addition, the Mac or even Windows has combined a regular audio system with something that is good enough for low latency work so I don't know why people keep saying "Oh, that's different".

With PulseAudio, people use it with all kinds of cheap hardware with crappy ALSA drivers, badly coded, closed source software with all kinds of ugly hacks.

Excuses, excuses. People have been using those drivers for years now, and if you've got something that has broken backwards compatibility then I'm afraid it's the fault of PulseAudio. That's the way it is.

ALSA has got to at least a reasonable state where things have stabilised over the past few years and rather than fix the remaining problems, look at the bottom of the stack and ask some serious questions we retrofit a pile of crap over the top of slightly less of a pile of crap to 'look like' that slightly less of a pile of crap?

When ANYTHING in the chain doesn't work properly, be it a stupid kernel configuration like Ubuntu's default one...

There's nothing wrong with Ubuntu's kernel. Using plain ALSA or OSS doesn't give the levels of latencies that Pulse does and JACK has been packaged with it for some time that works OK. You shouldn't need the kind of fine balancing Lennart is talking about in that mail to lower latencies, and quite frankly, he's talking crap.

...missing features of the ALSA drivers, badly coded applications that does all kinds of tricks to bypass the proper, well emulated ALSA APIs, they blame it on PulseAudio. *sigh*

That's because if you get something like ALSA to a reasonably stabilised state, as well as OSS being able to have and ALSA interface and vice versa, and you then get another self-important piece of software coming in over the top that sets everyone back then it is its fault.

Seriously, this kind of brain washing and mental illness over PulseAudio will set using Linux back on the desktop years. We're back to around 2000/2001.

Reply Parent Score: 3

strcpy Member since:
2009-05-20


[XXX] as got to at least a reasonable state where things have stabilised over the past few years and rather than fix the remaining problems, look at the bottom of the stack and ask some serious questions we retrofit a pile of crap over the top of slightly less of a pile of crap to 'look like' that slightly less of a pile of crap?


Oh, sir, you managed to capture the core problem of Linux.

Reply Parent Score: 3

Tuxie Member since:
2009-04-22

When JACK is running, non-JACK applications can't play sound at all unless you use the jack alsa-plugin and that has the same (or worse) kind of backwards compatibility problems that has given PulseAudio its bad reputation. Even dmix has these problems, with the difference that it transparently falls back to direct hardware access so you don't realize it until you try to make another application play sound.

You can get pretty low latency with PA with proper configuration and a properly configured kernel. It will however use much more CPU time and drain your laptop's battery faster. That's the price to pay for superlow latency. It happens with JACK also. PA tries hard not to drain your battery.

Ubuntu shouldn't ship with PA as its sound system without adjusting the system, applications and PA itself to work properly with it.

No, PA is not perfect. There are plenty of optimizations left to do, lots of features left to implement (particularly in the auto-configuration department) and many bugs to fix. Nobody is denying that.

I somewhat get the feeling that the same persons who are loud opponents against PulseAudio also were (or still are) against things like XGL/Compiz ("Playing videos worked much better with plain xvideo!", "Compositing sucks! It makes my Doom III drop frames!", "Window shadows don't make my Firefox render any faster! Useless!"). Now, a few years later, about all of the early issues have been fixed and the Linux desktop has become a LOT more modern (and nicer to use) because of it. I defended Compiz back then and I defend PulseAudio now, but I DO recognize that it has caused problems in certain areas and that it's partly unfinished.

Reply Parent Score: 1

boldingd Member since:
2009-02-19

Seriously, this kind of brain washing and mental illness over PulseAudio will set using Linux back on the desktop years. We're back to around 2000/2001.


OK, that's just assanine. I, for one, have no significant problems with Pulse. It's been more stable than the sound server in Vista (where unplugging my USB headset got me a blue-screen), and I'm not getting any noticeable latencies (and I am playing games on my Ubuntu box, actually). The worst I've gotten from Pulse, in the, what, 18 months I've had Ubuntu 8.4 installed on my Acer lap-top, is wonky channel names -- which is not exactly the end of the world.

And we're damned well not in 2000/2001. My first Linux (IIRC) was Slackware 8 in 2003, and I don't recall ever getting any kind of multi-channel sound mixing to work (with just Alsa), after spending about a week trying. Pulse has worked without any configuration effort on my part on all the installations I've tried it on, and I've never seen noticeable latencies from it (certainly not what I'm getting from ESD on RHEL4 at work!). You can complain about legitimate problems with Pulse all day long, but that Linux audio has come a long way from six years ago, and to claim otherwise is laughable.

Reply Parent Score: 1