Hallo!
Certainly the aubio functionality and the libxtract functionality (which gives some 50 features), are already available to Pd as an external (no need for a plugin host).
Yes, I have seen that. For these two libraries it's of course better to use the direct bindings ....
Although, from your list, it looks like you are mainly interested in the 'higher level' features?
At the moment I don't think about a particular feature. I am in general interested in music information retrieval and thought these plugins would be nice to have in Pd ...
I think it would combine very nicely into the PluginHost suggestion I added last week!
Yes this would be an option ...
For me, as I am interested in DSP and similar things, it would be also nice to additionally add new or other MIR/feature extraction algorithms. However, I think that it would be better to add such algorithms to libxtract or any other vamp plugin collection, then also other projects would benefit from it. But on the other hand this wouldn't be a pd-only project, so I don't know if it is suited for the GSoC program ... but in the end they would be also available in pd - through the VAMP plugin host external ;)
LG Georg