pulseaudio – flash blocks the audio device

On my x86_64 gentoo box, running gnome and therefore pulseaudio, I experienced the problem that when and after playing some flash videos (i.e. youtube) the sound device was blocked and no other application was able to play sound.  After killing the plugin sound worked just normal, but that was no convenient way.

64-bit flash plugin for Firefox

My first suspective was the 32-Bit flash plugin I used  in my 64-bit Firefox until now. So I replaced it by the new 64-bit plugin, which did not solve the problem, since it does also not use pulseaudio for playback. But I include the steps for completeness here:

echo “=www-plugins/adobe-flash- **” >> /etc/portage/package.keywords

emerge adobe-flash

For other linux distributions  like Debian, Ubuntu, Redhat or Suse you obviously have  to search the appropriate plugin and  install it the distribution-specific way. Afterwards you have to remove the 32-bit plugin from nspluginwrapper, which makes 32-bit plugins available for 64-bit firefox:

nspluginwrapper  -r /usr/lib/mozilla/plugins/npwrapper.libflashplayer.so

As I stated before this does not solve the problem, but at least it gives one a 64-bit flash plugin 😉

Make alsa applications use the pulseaudio server

There is a pulseaudio plugin for alsa, which is necessary for playback of alsa sound via the pulseaudio server. So the next step is to install this plugin. For gentoo it is contained in the alsa-plugins package. So for the gentoo way:

emerge alsa-plugins

Afterwards make sure that your /etc/asound.conf contains the following lines:

pcm.pulse {
type pulse
ctl.pulse {
type pulse
pcm.!default {
type pulse
ctl.!default {
type pulse

After restarting alsa everything that is playing sound via alsa now uses pulseaudio via the plugin and the sound device is no more used concurrently. One can playback via pulseaudio after using flash sites or even at the same time. Mission accomplished!

OSS emulation for pulseaudio

Sadly the above only works for applications directly using the alsa sound system. Applications depending on OSS (i.e. all Java Applications), using the kernel layer alsa oss emulation, still block the audio device, so the the kernel layer OSS emulation is a no go with pulseaudio. Include the corresponding modules in /etc/modprobe.d/blacklist.conf or remove the emulation completely from your kernel configuration.


Of course this only shuts off these applications completely but is neccesary for the further steps to work. We´re lucky, we can use a daemon which provides the OSS devices (/dev/dsp, etc.) and links them via fuse to the pulseaudio daemon. For this we need to load the cuse kernel module (add it to /etc/modules.autoload.d/kernel-2.6 and it gets loaded automatically on next reboot)  or when not available add the functionality  to your kernel configuration and rebuild your kernel.

kernel configuration for cuse

Now we´re ready to install ossp, the daemon I mentioned before. It is available from Sourceforge, probably also in your distributions package repository. For gentoo users, as usual there is a more easy way. I found an ebuild for ossp on gentoo bugzilla, which I got to work with minor modifications. You can download the modified ebuild here: ossp-1.3.2.ebuild (863)

To use the ebuild, just copy it to/usr/local/portage/media-sound/ossp/ . You probably have to create the directory. Then run

ebuild /usr/local/portage/media-sound/ossp-1.3.2.ebuild digest

Be sure to include the following line in your /etc/make.conf.


Also include ossp into your /etc/portage/package.keywords

echo “media-sound/ossp **” >> /etc/portage/package.keywords

Afterwards just

emerge ossp

For having osspd started automatically on every system boot I lazily included it in my /etc/conf.d/local.start.

echo /usr/sbin/osspd >> /etc/conf.d/local.start

Now sound should just work as one expects it to. Different sources can playback at the same time. No blocked devices occur because of concurrency, no matter which sound API the applications use.



BombStrike´s blog: How to use two different computers with two differents OSes seemlessly


Linux Live: ALSA and Jack Cooperate using PulseAudio

Gentoo Bugzilla: osspd ebuild

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Pimp up your internet tablet


Did you ever ask yourself how to make your internet tablet more powerful?

For a Linux based device like Nokias N810 this question is quite easy to answer.  You can easily increase overall performance and responsiveness by using a “better” kernel than the stock kernel on your internet tablet. A further advantage is that you can add features that are not available in the stock kernel. Below you will find instructions on how to build your own optimized preemptive kernel or how to install my prebuilt kernel.

Nokia N810 Internet Tablet
Nokia N810 Internet Tablet

In both cases the following features are covered:

  1. preemtive kernel
  2. high-speed sd-cards
  3. screen rotation
  4. more granular backlight sertting
  5. easy-debian image

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