Phonon xine backend future

Colin Guthrie phonon at
Tue Feb 22 10:29:53 CET 2011

'Twas brillig, and Harald Sitter at 21/02/11 21:57 did gyre and gimble:
>> This also leads to maybe more deeper concern : do the audio processing
>> plugins should be fixed in backend ? Could we make a interface which
>> is backend independent - adding a possibility to the frontend app to handle
>> the effects ? Wouldn't be this more flexible ?
> We could, if someone thought up a design that actually made this
> possible and at the same time allowed to scale from dumb to
> sophisticated media frameworks, I personally do not see how though.
> That is if I understood you correctly, that the application is then
> capable of manipulating the audio/video streams directly. Which is a
> difficult thing as the phonon backends would have to steal the raw
> data from the underlying frameworks, hand it to the application and
> then feed it back into the framework once the app is done with
> whatever it may want to do. This can not work as less frameworky
> backends (think MPlayer or VLC) cannot do such complex things. Even
> for those frameworks that can do it, it is extremely difficult as
> there is no sensible way to ensure time accuracy of the data across
> the framework, phonon and the application. That said, we already
> provide interfaces that do not need to care about feeding things back
> to the framework. Like AudioDataOutput with which one can operate on
> raw audio data, but cannot feed it back into the backend, which is
> useful for analyzers for example.

Those who know me will likely know what I'm going to say......

PulseAudio git master exposes an equalizer sink that can be activated
pretty easily. There is an independent GUI that can be used but
obviously it would be nice to just push this through to applications if
they support it.

When this is released, I fully intent to implement (or mentor: which
reminds me I should add this as a GSoC) support for PA equalizers across
all Phonon backends via PA (i.e. bypassing the backend completely.

There are lots of things to consider about when this is and is not
possible (e.g. you cannot equalize when using passthrough from a media

In a related theme, there are also other things that will be made
available automatically and do not require specific support in Phonon,
like AEC (echo cancellation) that can be automatically activated when
using the "Communications" category in Phonon. These will also "just
happen" when PA git master is released.

Obviously integrating support only for PA on Linux wont please everyone,
but as PA is the default on most Linux distros now (even KDE based
ones), I think it will catch a large proportion of users. And it's my
desire to see PA supported as well as possible in Phonon, so adding such
features is a bonus for users.



|     Colin Guthrie      |
| |

More information about the Phonon-backends mailing list