Adding spatializer to Phonon?

[tim]

On Tue, 2011-02-22 at 09:32 +0000, Colin Guthrie wrote:
> 'Twas brillig, and Harald Sitter at 21/02/11 22:24 did gyre and gimble:
> > Aloha!
> > 
> > On Mon, Feb 21, 2011 at 9:27 PM, tim <tej at melbpc.org.au> wrote:
> >> - Would you agree with this? Would Phonon be the right place to add a
> >> spatializer? If not, what is a better place?
> > 
> > No. The actual frameworks/libraries as used by the backends should
> > have this, or if all fails one could also do it in the individual
> > backends (given the underlying framework/library actually allows that
> > sort of manipulation to the audio stream). What Phonon could and
> > should do though is expose such functionality to the
> > applications/user. For this we already have an interface ...
> > BackendCapabilities::availableAudioEffects(), so if you want to have a
> > quick success for starters you could try to expose VLC's existing
> > spatializer (I hear libvlc_audio_filter_list_get is a related function
> > needed there ;)).
> > 
> > I am pretty sure GStreamer also has such a thing amongst its billion
> > billion plugins, so you could easily cover the two important backends
> > on Linux.
> 
> And just to keep my PA theme going, there could be ways and means of
> implementing this in PulseAudio so that all Linux backends would benefit
> (although this may be overkill if it's supported in GST+VLC already).
> 
> If it was implemented in PA, it could be done as a virtual sink (like
> equaliser support and AEC already is), or perhaps you could just
> configure a LADSPA sink (I'm not sure as I don't really know much about
> LADSPA).
> 
> I need to get the multi-channel LADSPA stuff merged now I come to think
> of it....
> 
> Cheers
> 
> Col

Thanks. I learned that pulse-audio supports LADSPA and there is already
a bs2b plugin for pulse-audio so it's all there already - all I need to
do is configure it.

I'm thinking of writing a more ambitious one which I will probably
target to the Jack plugin API as it seems a lot simpler to program.

Thanks for your help
Tim Josling