Ubuntu Jaunty problems with Pulseaudio

[steve]

Having been struggling with Pulseaudio since upgrading Ubuntu from Intrepid 8.10 to Jaunty 9.04 I finally decided to do away with Pulseaudio by following the instructions here: http://idyllictux.wordpress.com/2009/04 ... io-at-bay/

[EDIT] Before you decide to try this yourself, read the next couple of posts.[/EDIT]

Audacity now behaves perfectly and switching from internal microphone to the external one works by either selecting hw0,0 for the internal mic and hw0,4 for the external one, or alternatively leaving Audacity Preferences set to using ALSA(default) as the recording device and then using Alsamixer to switch to whichever input I wish to use.

The only problem now is that I've lost the ability to record "stereo mix", so I'm working on that now.

BTW It is OK to uninstall pulseaudio even though Synaptic says that it needs to uninstall Ubuntu Desktop as it only uninstalls the metapackage and not the whole desktop.

[steve]

Update: It looks like a-loop (required for recording stereo mix with my sound card) has been left out from Jaunty - I presume on the basis that with Pulseaudio installed it is not required.

Also without Pulseaudio it seems that I cannot switch the sound output from Firefox from playing through the internal sound card to my external USB sound card. I guess this will be the case with other applications too, so it looks like for me at least Pulseaudio will have to go back on.

[steve]

So now that I've decided to stick with Pulseaudio, at least for the time being, it's time to look at how to use it properly.

After spending a bit of time with it I've come to the conclusion that it's not that bad after-all, in fact it is very useful. The main problem is that there does not seem to be much good information about how to use it, especially with Audacity, so time to write a brief guide.

To start with, there is a decent introduction to Pulseaudio on Ubuntu here: http://ubuntuforums.org/showthread.php?t=789578

To be continued....

[steve]

As I mentioned in my previous post, there is a nice introduction to Pulseaudio in Ubuntu here: http://ubuntuforums.org/showthread.php?t=789578

A few extracts (for those too impatient to read the whole thing)

PulseAudio is an advanced sound server which has been included in Ubuntu (i.e. the standard GNOME version) since the release of Hardy Heron (8.04). Unfortunately, Hardy shipped with a suboptimal configuration of PulseAudio which has resulted in users experiencing various problems, ranging from sporadic crashes in Firefox to sound mixing being completely broken.....

As of April 2009, I recommend all users who are interested in PulseAudio to install the latest release - Jaunty Jackalope (9.04). The Ubuntu developers have done an excellent job with PulseAudio integration and configuration in this release.....

Q. What exactly is PulseAudio?
A. From the homepage:

PulseAudio is a sound server for POSIX and Win32 systems. A sound server is basically a proxy for your sound applications. It allows you to do advanced operations on your sound data as it passes between your application and your hardware. Things like transferring the audio to a different machine, changing the sample format or channel count and mixing several sounds into one are easily achieved using a sound server.

Simplified: PulseAudio is responsible for playback and mixing of audio on your system. It is not a sound driver - in fact, it runs on top of the Advanced Linux Sound Architecture (ALSA). Aside from all the cool effects PulseAudio provides, it serves as a replacement for ALSA's virtual sound mixing device (DmixPlugin, or "dmix") - thus allowing multiple applications to share access to your sound card.

Q. PulseAudio? Bleh! I don't want it on my system.
A. Well... tough! PulseAudio is already installed and active on Hardy and Intrepid by default; it replaces ESD (ESound Daemon) for system sounds, and most of Ubuntu's default applications already use it (Totem, Rhythmbox, and any other applications using the GStreamer framework). Although some high-profile applications support PulseAudio natively (such as VLC and mplayer), most applications use plain ALSA or OSS output, and thus don't have native PulseAudio support.

Q. If PulseAudio is already installed, why do I need this guide?
A. While PulseAudio has been installed by default since Hardy Heron (8.04), we dropped the ball when it came to the configuration part. A quote from the main PulseAudio developer, Lennart Pöttering:

Some distributions did a better job adopting PulseAudio than others. On the good side I certainly have to list Mandriva, Debian, and Fedora. OTOH Ubuntu didn't exactly do a stellar job. They didn't do their homework. Adopting PA in a distribution is a fair amount of work, given that it interfaces with so many different things at so many different places. The integration with other systems is crucial. The information was all out there, communicated on the wiki, the mailing lists and on the PA IRC channel. But if you join and hang around on neither, then you won't get the memo. To my surprise when Ubuntu adopted PulseAudio they moved into one of their 'LTS' releases rightaway. Which I guess can be called gutsy -- on the background that I work for Red Hat and PulseAudio is not part of RHEL at this time. I get a lot of flak from Ubuntu users, and I am pretty sure the vast amount of it is undeserving and not my fault.

When PulseAudio is running, it requires exclusive access to your sound card in order to work correctly as it assumes responsibility for mixing application's sounds instead of ALSA's "dmix" device. If you launch a "regular" application that does not have explicit PulseAudio support, it will most likely try to open the "Dmix" device - and this will deprive PulseAudio of control over the sound card. From the user's perspective, they will observe that audio mixing between applications is broken.

PulseAudio includes ALSA plugins (within the package "libasound2-plugins") which are designed make regular ALSA applications remap audio to the PulseAudio server (and thus avoid mixing problems as described above). Unfortunately, Hardy Heron shipped without these plugins enabled (or even installed) by default, which is causing many, many audio mixing issues for users. To compound the problem, the version of these PulseAudio ALSA plugins in the Hardy repositories do not function correctly, so updated versions are required for ALSA applications to work correctly with PulseAudio.

So now that we all know why we've been having difficulty with Pulseaudio....
For anyone that has upgraded to Jaunty, see the rest of that article for setting up Pulseaudio correctly.
If you have a clean install of Jaunty, it is still worth checking the article to ensure that your set-up is correct.

Pulseaudio Mixer and Pulseaudio Applet
If you have these installed you should see them in the "Sound and Video" section of the Applications menu. If they are not present, use Synaptic to install them ("pavucontrol" and "padevchooser")

Note for VLC users: Also install "vlc-plugin-pulse" so that you have full Pulseaudio support in VLC.

If you have just set-up Pulseaudio, restart your system before proceeding.

Next section: Setting up Audacity to record anything with Pulseaudio.......