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PulseAudio Creator Responds To Critics
Dan Jones writes "As recently discussed here, Linux sound development has come under fire for being overly complex and, more specifically, PulseAudio has been criticized for not being a 'good idea.' In a lengthy interview, PulseAudio creator Lennart Poettering has responded to the many critics of the new-generation sound server and says such complaints and criticisms about PulseAudio in some Internet forums are not really shared by the vast majority of technical people. While Poettering admits PulseAudio itself is not bug-free, he believes the majority of issues are being triggered by misbehaving drivers or applications."
When an application can make the soundsystem stop working for all other applications, than there is a bug in the soundsystem, not just the application that caused the problem.
------ Take away the right to say fuck and you take away the right to say fuck the government.
The idea is great. PulseAudio is an excellent solution for networked audio and thin unix clients. Now the problem is the people and the distros installing it by default on a desktop where it is utterly useless. No matter how close to bug-free it is, it is an unneeded source of bugs in that case.
This is not entirely true.
Now, I don't know what the exact bugs are that are causing problems. But the API should be stable no matter what happens to the outside. There should be no way to destabilize or crash the audio layer from a usermode application. So, if by "expect more correct behavior from the apps" he means "garbage in, garbage out", then that's fine. But if by "expect more correct behavior from the apps" he means "no error checking and if any app screws up then everything melts", then that's not fine.
I don't know which he means, but I've seen instances of both.
Breaking Into the Industry - A development log about starting a game studio.
The problem is that the implementation sucks, and that bugs are being ignored.
I'll perhaps reconsider my stance when pulseaudio starts using less CPU than the JVM when playing Puzzle Pirates. Finally something more bloated than Java, I guess.
Finally! A year of moderation! Ready for 2019?
While Poettering admits PulseAudio itself is not bug-free, he believes the majority of issues are being triggered by misbehaving drivers or applications.
Well, the way I see it, I can either use alsa and have (as far as I can tell) no bugs, or I can use PulseAudio and have more features and more bugs.
That might not be PulseAudio's fault, but it still means that if I use PulseAudio I will have a buggy sound system. Why do I want that? Why do I want it even if it's only buggy until all the applications get fixed?
Also, the promise of networked sound is kinda... meh... maybe I'd be happy if all my laptop sound got moved to my desktop box (which is connected to my stereo) automatically whenever my laptop is connected to my home access point (and, conversely, my desktop's sound automatically gets routed to my laptop whenever my laptop does an ssh home and is not around my home access point). But as far as I can tell, this is a bitch to set up, and I'm really not inclined to go clicking around some unintuitive menu system to set my sound up right every time I leave home or go back.
So what's the benefit of PulseAudio again?
The largest problem with Linux audio is not really any particular driver model / sound server. OSS, ALSA, PulseAudio and Jack all work when set up properly, with supporting hardware, and supporting software. But it's never a given that a particular app will support whatever you're using, or give you the choice to select your output device if you have multiple sound cards.
I've been running Ubuntu for a long time now, and recently installed Windows as a dual boot for making music. Why? I can spend X hours on setting stuff up, or I can spend X hours on making music. I can simply count on any app that matters supporting ASIO or DirectSound on Windows.
While I actively try to convert people to Ubuntu for regular desktop apps I still tell people who plan to do audio/video stuff to go for Windows/OS X. While it's totally doable to set up a working environment in Linux if you know what you want and which apps you want, I like to play with stuff for fun. I'd rather invest my time in having fun creating content than trying to get stuff to work.
(And yes, I've tried Ubuntu Studio. Nice, but not there yet for me.)
.: Max Romantschuk
The 4Front interpretation of GPLv2 is irrelevant - the source code is triple-licensed under GPLv2, CDDL and BSD licenses. ALSA is an excellent example of Linux throwing away a solid API and implementation that could have evolved to support the few critical features it lacked (which is exactly what happened in FreeBSD for example) in favour of a half-baked alternative. The original ALSA API is poorly designed by people who clearly have very limited knowledge of OO principles, but wanted to apply them all the same. This piss poor API was never well documented, and the actual audio drivers are not of the same quality as the ones in OSSv4. The ALSA developers answer to the poor API? Slap another, equally poor, equally undocumented API on top of it. What a fucking mess.
Even if he may be 100% right about that: way not to get the point!
I don't care whether problems are caused by the kernel, a driver, an application, the phase of the moon, or whatever. The thing is, if some "trivial" piece of hardware which has been part of mostly every computer since about 1990, still *does not fucking work* correctly today, I don't give a rat's ass whose fault that is. Especially if it appears the same "problems" have been solved satisfactorily at least 10 years ago on every other OS in mainstream use.
In the meantime, Linux has changed both the audio driver model (ALSA, OSS, who knows what else), and in addition to that, the "application interfaces" (arts, esd, PulseAudio, etc.) so frequently, that it is hardly any wonder that application developers are taking the piss and not updating their software to match the bugs/workarounds to whatever the current "flavor of the week" API for audio interfacing is.
Perhaps PulseAudio is just getting most of the "blame" because it is the most recently changed part of the audio subsystem, so if things used to work before, and now they don't, of course you're going to blame PulseAudio. Even if it is not by itself the "real" culprit.
Every expression is true, for a given value of 'true'
Do more than .0001% of linux users need autoforwarding, or network transparency at all? Or should we focus on what the other 99.9999% want, which is high performance, low latency, non-crashing sound like the other two major OSs have.
I never thought I'd see a Linux advocate use the Vista Defense! It's the drivers, it's the software, it's something, but it's not my code!
At least with Vista the problems with video drivers, and various other hardware devices was sorted out within a couple of months. In Linux the way audio is handled is an absolute mess.
The sound on my =bare metal= install of Fedora 10 didn't work.
After much forum-searching, config tweaking, and pounding-of-keyboard, I eliminated PulseAudio.
The sound worked.
Tell me again about PA's awesomeness.
Comment removed based on user account deletion
I'm an OSSv4 converted too - being being unable to get vmix or Pulse to work right, Alsa could turn the volume as high as Windows. Now in OSSv4 everything works fine, except being unable to detect the jack, which is annoying.
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"The kernel has exception handling tables. This is used for a variety of things, primarily access to user space memory. My day is not ruined."
The current treatment of FPU exceptions is 'panic'. Go on, try to persuade kernel people to change it.
"No. Look, I could eliminate userspace entirely if I wanted to. (it's just a trivial change to not exec init) I can throw pretty much anything into the kernel. The kernel rules all."
Go on. Try to read config files from the kernel space, for example. Let's see how far you'll fly when Linus Torvalds kicks you.
"Um??? They sure are, and I'm not limited to threads. I can use tasklets, softirqs, regular old interrupt handlers, or my own evil invention. I can even disable interrupts if I please."
And I can set realtime priority for a thread, which in practice is more than enough.
"I didn't suggest it required the X server. I said it was the same sort of thing. It's a userspace program that is unable to create hooks for SE Linux policy or get capability bit allocations. Sure, I can use SE Linux as a big hammer, but I can't ask SE Linux to control the internals of non-kernel code."
Uhm. But it can. You can't use capability bits, but nobody uses them anyway. Besides, PulseAudio can use _userspace_ authorization system (DBUS + rtkit) which is right now much more usable than anything SELinux people can come up with.
A lot of devices stream data over a network and play it locally as audio. That does not necessarily make any of them a "network based" audio device in the sense that they can be driven by PA.
Audio is not unique in needing device ACLs adjusted; it should not need a unique solution for doing that. In fact, having an audio server handle ACL adjustments when something else does that is a violation of the Unix philosophy of chaining together simple tools that focus on one thing.
Application-controlled latency is good. Library-enforced latency is bad. Sending audio from one user-space process to another is a case of the latter.
After reading your post made "as a PA developer", I'm even more down on it than before.
latency sucks... If I play a note on my guitar or keyboard, then I do not want to hear the sound more than a couple of milliseconds late... this is precisely why I still do my music recording on a windows box... I still can't get rid of it much as I really want to... I did have a perfectly good Ubuntu Studio setup going back on the LTS (Dapper Drake) before the current one, but certain issues pushed me into upgrading to the next LTS (Hardy Heron) and boom... pulseaudio screwed it all up... I was completely dumbfounded when I discovered it was an experimental sound system just dumped into the LTS without any attempt to get the default settings correct. I expect the LTS version of Ubuntu to actually work out of the box. So as a result, I got my XP box out of mothballs and went back to using XP for recording.
Donald 'Duck' Dunn: We had a band powerful enough to turn goat piss into gasoline.
You're confusing synchronization and latency. There's no particular reason you can't buffer up a few seconds of audio, yet make sure that audio is played exactly when the video calls for it.
I'm afraid you haven't yet distinguished between OSS3 and OSS4. Have you TRIED IT? If not - stop your belly aching. If you have tried it, then put some comments on the OSS4 contributor's site. Since I'm not a developer, telling me how bad it is accomplishes nothing.
Once again, OSS4 solves all of my problems. Sound just works for me, without a hitch.
"Windows is like the faint smell of piss in a subway: it's there, and there's nothing you can do about it." - Charlie Br
I've had three systems with audio problems. Two Ubuntu-based (8.04, 9.04), a third OpenSuSE-based. All with PulseAudio. All had oddities- ranging from the sound working only during X session startup/shutdown (and not in-between), through to the audio skipping, repeatedly, when changing the current desktop. These were on reasonably decent machines, by the way. Machines that should gobble up and spit this data so fast that it barely dents CPU usage.
In each case, disabling PulseAudio and using, well, anything else, caused the problem to go away. OSS, ALSA, didn't matter, they both worked. Sometimes it was easy to remove PulseAudio, and sometimes it took a bit of work. Ubuntu 9.04 was a challenge. No, scratch that, it was a fight.
I look around, I see horror stories and widespread problems with PulseAudio.
I see claims that it works, if you configure it "properly". You know, I heard the same vague defence regarding Windows' instability. I didn't believe it for Windows either.
I've heard that PulseAudio has a great set of features. However, I have no interest in digging into what these features might be. The core feature that I want above all else isn't supported by PulseAudio. That feature?
Playing seamless audio.
PulseAudio can't even get that right. Stutters and skips are the norm, audio systems that worked previously no longer do, and the backers of this abomination are in abject denial about it. There are widespread complaints about it across multiple applications and multiple operating systems, and still it "isn't configured properly". You can't be serious. Complaints about PulseAudio are not really shared by the majority of technical people? Oh, yes they are.
If you want to provide a reasonable sound system, a *core* focus has to be on providing a working sound system. Get the core functionality right, then move onto features. Stability, correctness. Get the basics right. Also understand that API users may stuff things up, and falling over and dying is not the correct thing to do. The infrastructure needs to be resilient, not fragile.
PulseAudio did *not* do this. Any of this.
The order of the day seems to be to blame everything *but* PulseAudio. The apps are broken, the drivers are broken, the operating system maintainers didn't integrate it properly, it's not configured properly for the user's machine, the people complaining wouldn't be complaining if they were more technical, a lot of distros have adopted it so it must be good. Did I miss anything here? This has been the argument thus far.
I'm going to be different. I'm not going to blame the developers, the applications, the users, the knowledge of the users, the operating system developers, or anyone else. I'm going to blame the one at fault, the *cause* of these problems. The one thing in common with this incredible list of problems.
PulseAudio is completely and utterly broken- in design, in implementation, and in application. It is horrendous, shameful, and embarrassing.
Yes there is: you don't want to be playing a game, and only seeing responses to your inputs seconds after you do things. Any noticeable input lag in a game ruins the experience. Ideally, you want no more than one frame of latency between reading inputs, running an iteration of your engine and getting it out to the display/speakers/haptics. Not all content is pre-recorded.
Are you serious? Faddishness, I agree with. Popularity - popularity is something worth considering. Popularity implies community, and with a large community chances are most elements of a given problem have already been coded by someone else. Consider Perl and CPAN - a good reason to use Perl. But popularity is not enough to make me choose MySQL over PostgreSQL for instance.
Lastly - the end user as a priority needs to die? That really depends on who you are writing the software for. If it's an operating system and you want it to compete with a Windows or OSX on some level, considering the end user is unavoidable. A vastly larger feature set and complexity than say, OpenBSD, is also unavoidable. Lack of time to audit the code and remove bugs to the degree that OpenBSD has done is also unavoidable. Maybe this goes some way to explaining the quality of the code and the size of the user base of both operating systems.
If I have seen further it is by stealing the Intellectual Property of giants.
All these informed-sounding folks, living in some perfect netherworld that doesn't really exist. *sigh*
If I have a recording that is too quiet (for whatever reason), it is reasonable to be able to turn it up so that it's not too quiet anymore.
Not every recording is stuffed all the way up to the max at 0dB. Some are far quieter, whether on purpose or on accident. If I have a recording which peaks at -20dB, then I ought to be able to apply at LEAST 20dB of gain to it without jumping through hoops.
This is not an uncommon problem, and the best (simplest) solution is just to turn it up -- however that's done. It's been awhile since I've done any serious audio in Linux, but if PulseAudio or ALSA or whatever combination thereof requires me to buy extra hardware (WTF?) to achieve this very simple and obvious function, then it is very broken[1] indeed.
And before anyone replies and says "Oh noes! If we give the users gain, they might makes teh Distortions!!!!" This is broken in the "I'm sorry, Dave, I can't do that" sense. It's REALLY fucking stupid that the same operating system which allows you to do "dd if=/dev/urandom of=/dev/sda" without prompting WILL NOT PROVIDE MEANINGFUL AUDIO GAIN.
Kid-proof tablet..
I'm really curious - I haven't tried OSS4 yet, but the one thing I haven't ever gotten working on linux is the following setup:
Analog/Digital speakers, with a USB headset.
Can OSS4 handle USB sound? Can it mix multiple streams? Does it have an easy way to switch between input/output devices?
Pulse gave me hope for the above. Then fell flat on its face. I've never been able to get dmix to handle this setup, and ALSA doesn't seem to do it.
I hate to say it as a linux fanboy, but I want audio like Windows. Right-click on my audio button, and in two clicks I can choose my input and output devices, and all sounds are seamlessly mixed to make that happen. I don't really care about network audio, or any of the other fancy-ass shit that pulseaudio is supposed to do.
Really, I use a desktop, and I have multiple audio sources and devices. Mix them automatically, and give me a quick gui control for which piece of hardware should be handling each. That's all I really want.
Velociraptor = Distiraptor / Timeraptor
Gosh, I never thought of that: I can just take the source audio and adjust it up with mp3gain or sox or something! How short-sighted of me. Thank you for showing me the error of my ways. [/sarcasm]
Of COURSE it's broken, but that doesn't mean it's the application's fault. Sometimes, the mic audio on (say) the camcorder is just too low, and the person running the thing doesn't have the knowledge, skill, or time to fix it. Am I really supposed to figure out how to adjust the gain on some H.264 multiplexed audio/video just so I can show a video to a friend on my laptop, with audio at a reasonable level?
Seriously?
Cuz, I mean: I don't have time to supervise every production that ever happens in every corner of the world, and accordingly things are very simply too quiet from time to time.
Really, folks. I want to live in your happyplace where all audio levels are always sane, everyone has a clue, and all volume controls are simple attenuators. I honestly do. But my reality doesn't work that way.
Kid-proof tablet..
Look, I understand that getting this stuff right is a hard problem and takes some effort to get resolved, and that' s not necessarily the fault of the developer. But it's not my fault either. I don't have time for this kind of thing - while there was a day when I really enjoyed spending a bunch of time fiddling around with my computer to get it to work right, those days are mostly over for me now. I need sound to "just work", and if Pulseaudio doesn't, then I'm not using it.
Ladies and Gentlemen!
See here the man who is unaware of the existence of laptops! Yes, this sad specimen of a Slashdot poster actually believes that all computers have external speakers and amplifiers plugged into them at all times. The thought of using a laptop to play a funny YouTube clip during a break in a meeting has never occurred to this being! Fear him, and pity him!
Comment of the year
> Each time Linux redesigns some subsystem there are problems, and we see
> the same people bitching about how we should use $ALTERNATIVE instead...
No, the situation with Pulse is different in several ways.
1. With previous changes there was pain in the transition but even those suffering most could see that the change was going to be a good thing. Not so with Pulse. Pulseaudio is a system that would be, at best, a minor improvement in a perfect world and a never ending nightmare in the real one. Harsh charge? Read on.
2. Pulse blameshifts all it's problems to apps and drivers. Ok, apps (open source ones anyway) will eventually get fixed. Drivers won't. Motherboards do not ship with sound drivers for Linux. Linux ships generic drivers for the sound chips on popular systems. There is a big difference. Board makers connect those generic chips in a myriad of ways, poorly documented if at all outside the Windows driver. Manual intervention and exploration is usually required to figure out what is connected to what and how best to configure things. Pulse's design is to remove all controls except one big volume slider.
Examples: My desktop system requires careful balancing of the VIA DXS, PCM and Master sliders to get enough output to drive my speakers and avoid clipping in the digital side of the system. My Thinkpad needs an easy way to mute the master output to silence the internal speaker while leaving the external output alone to get good results while docked. Feel free to add your story, if enough of us provide use cases where ONE slider won't work.... they will ignore all of us. :(
3. It still isn't even clear exactly what problem Pulse is supposed to be a solution to. Every major application had finally achieved stable ALSA support, and ALSA works. Being able to move sound streams between devices while they play is gee whiz and all, but it isn't a problem most of us are needing enough to endure a lot of pain to get. It might be worth the pain if we were being promised this would be THE audio solution but the Pulse devs themselves admit it isn't, Pulse can't touch JACKs realtime features.
4. But the biggest problem with Pulse is the devs. There are real problems but this time, unlike past transitions, this isn't a case of they haven't fixed all the bugs yet, it isn't even a case where they tell ya to submit a damned patch if ya want your problem fixed NOW. Both of those cases are normal examples of Free Software development. No, what is new is bugs being closed with "That problem can't exist within our philosophy and thus can't be fixed, buy new hardware and hope it works." In other words, that problem can't be fixed without exposing complexity we don't believe should exist. They have forgotten the second half of "Make things as simple as possible, but no more."
Democrat delenda est