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Wed, 05 Aug 2009

Oh Nine Sixteen

As a followup to Oh Nine Fifteen here's a little overview of the changes coming with PulseAudio 0.9.16 which will be part of Fedora 12 (already in Rawhide; I think Ubuntu Karmic (?) will have it too).

A New Mixer Logic

We now try to control more than just a single ALSA mixer element for volume control. This increases the hardware volume range and granularity exposed and should also help minimizing problems by incomplete or incorrect default mixer initialization on the lower levels.

This also adds support for allowing selection of input/output ports for sound cards. This is used to expose changing between Mic vs. Line-In for input source selection and Headphones vs. Speaker for output selection (of course the list of available port is strictly dependant on what you hardware supports). The list of available ports is deliberately kept minimal.

Thanks to Bastien the newest GNOME Volume Control now exposes profile/port switching quite nicely, which he blogged about. This screenshot shows how the port (here called 'Connector') can be selected in the new dialog.

The mixer rework also allows us to handle semi-pro/pro sound cards a bit more flexibly. For example, which profiles/ports are exposed in PulseAudio or how specific mixer elements are handled can now be controlled by editing .ini file like configuration files in /usr/share/pulseaudio/alsa-mixer/. Read this mail for more information about this.

UPnP MediaServer Support

PulseAudio now integrates with Zeeshan's fabulous Rygel UPnP/DLNA MediaServer. If enabled Rygel will automatically expose all local audio devices which are managed by PulseAudio as UPnP/DLNA MediaServer items which your UPnP/DLNA MediaRenderers can now tune into. (Meaning: you can now stream audio from your PC directly to your UPnP DMP (Digital Media Player) device, such as the PS3.) Communication between Rygel and PulseAudio follows our little Media Server Spec on the GNOME Wiki. This nicely complements the RAOP (Apple Airport) support we introduced in PulseAudio 0.9.15. In one of the next versions of PulseAudio/Rygel we hope to add support for PulseAudio becoming a MediaRenderer as well. This will then not only allow you to stream from your PC to your DMP device, but also allows PulseAudio to act as "networked speaker", which can be used by any UPnP/AV/DLNA control point, such as Windows' Media Player.

Hotplug Support Improved

If you select a particular device as the default for a specific application or class of streams, then when unplugging the device PulseAudio moves the stream automatically to another audio device if one exists. New in PulseAudio 0.9.16 is that if you replug the audio device the stream will instantly be moved back, requiring no further user intervention.

Also, PulseAudio now includes some implicit rules for doing the 'right thing' when finding an audio device for an application. For example, unless configured otherwise it will now route telephony applications automatically to Bluetooth headsets if one is connected, in favour of the internal sound card of the computer.

Surround Sound Support for Event Sounds

This is more a new feature of libcanberra than of PulseAudio, but nonetheless: we now support surround for events sounds. This allows us to play full 5.1 login sounds for example, in best THX cinema fashion. We'd love to ship a 5.1 sound for login by default in sound-theme-freedesktop. We'd be very thankful if you would be willing to contribute a sound here, or two! A sound a bit less bombastic than the famous cinema THX effect would probably be a good idea though.

And then there's of course the usual batch of fixes and small improvements. A substantial number of non-user visible changes have been made as well. For example, as HAL is now obsolete PulseAudio now moved to udev for its device discovery needs. We replaced our gdbm support by support for tdb. Also, we stripped all security senstive code from PulseAudio, and ported it to use RealtimeKit instead. For the upcoming distributions that means that PulseAudio will run as real-time process by default, improving drop-out safety.

And for some extra PA eye-candy, have a look on Impulse!

posted at: 02:30 | path: /projects | permanent link to this entry | comments


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Lennart Poettering <mzoybt (at) 0pointer (dot) net>
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