Ok folks, this is a long email of me trying to figure out different options for panning and spatialization, and with some questions. I'm planning to offer some spatialization objects for ELSE. With the new cool features of MultiChannel Connections in Pd, I wanna offer objects that can spatiaze with an arbitrary number of channel outputs in a single connection.
I see I'll have to get into "ambisonics", but first I am checking "VBAP", and some options we already have out there in the world. About VBAP by V. Pulkki see: http://legacy.spa.aalto.fi/research/cat/vbap/
So, there's a "vbap" library that used to come with the late Pd-extended. This is a control object, for 2D and 3D configurations that you set with messages. It outputs lists with speaker number and gain, so you can use [route] to send gain values for each output. It has the parameters of: "azimuth" (which is for both 2D and 3D and represents the angular distribution around the listener); "elevation" (only for 3D and represents speakers above or below); and "spread", which spreads the sound to adjacent speakers. Now, the disposition of speakers in this way should be equidistant around the listener, for a ring or semi ring distribution in 2D, and a dome or semi dome in 3D!
There's an external for SC which seems to work the same way, with the same parameters, but it already takes the input and it spits the spatialized channel outputs.
There's also a couple of externals by Pierre Gullot at https://github.com/pierreguillot/vbap - The vbap.coeff object is very similar to extended's [vbap], but it has no spread value (unfortunately) and [vbap~] is a nice and much more convenient solution that takes the audio input and already pans it, like in SC, but it also misses the "spread" parameter. I don't know why it misses this, seems like a cool feature...
There's also the CICM tools library, that I uploaded to deken a few years ago, it has an external that is also named [vbap~], but it's different from Pierre's. First, it is only 2D! But then, in the 2D world, it is more versatile and has more features! You don't need to set the speakers in a circular ring or partial ring that are equidistant to the center point! So yeah, you can configure a speaker disposition in a rectangular room and do other crazy stuff. It does not have a 'spread' parameter per se, but you can move the sound in the 2D space with cartesian coordinates (or polar) and you can also set a central disk radius. I have to study better how these different parameters actually work, but it kinda 'spreads' the sound over different speakers. Nonetheless it doesn't really seem like an actual "spread" parameter and I wonder if such a parameter could also be included here. Anyway, As you can see, this is the "odd one out", and I wonder why... I kinda like its versatility better. As for a 3D version, I haven't seen one that would work like this object where you could have a 3D point in the 3D space...
By the way, CICM tools has 2 other objects, but for ambisonics: [ambipan~] and [ambicube~]. The [ambipan~] object is much much like [vbpan~], so it spatializes in the 2D plane and you can set a specific point, not just an angle. It seems just to change the algorithm/calculation. The [ambicube~] object is highly related to [ambipan~], but 3D and you can set a point in the 3D space. The caveat is that it is fixed to a specific 8 speaker configuration, unfortunately. All the other objects can have arbitrary number of speakers and configuration.
The AudioLab library has a [pp.spat8~] object as a vanilla abstraction. It's fixed to 8 speakers, not surprisingly, but you can set speaker position arbitrarily with a GUI. You can set a cartesian point and it has a spread parameter. So it relates to things from above, but I bet it has nothing to do with "VBAP". It's just a panner with a spread parameter, right?
So, I really know nothing about VBAP or Ambisonics, but I'm starting to offer some spatialization objects for ELSE. I had so far only some very modest routing options, like [xgate2~], which you can use to route to different speakers with crossfading. I also added now a spread parameter and a MultiChannel connection aware version.
I already have a new object that is like SuperCollider's PanAZ. It's similar to [xgate2~] but it's circular, and you can only set the angle and a spread parameter. That is, you cannot set a cartesian coordinate. The speakers are equidistant and equally spaced in terms of angles. This is actually highly related in terms of parameters to extended's [vbap] in the 2D version, the only restriction is that you cannot arbitrarily set the disposition of speakers, but it's also a start. I believe it can't compare to an actual "VBAP" though.
I have [pan4~] which is not really good as I see it. It's like SuperCollider's Pan4 object and you can set a cartesian coordinate. There's also [pan8~] in ELSE, which expands from [pan4~] and has a spread parameter and it is also a simplified version of [pp.spat8~]. I could make it with an arbitrary number of speakers and MultiChannel aware, but it would restrict to a circular distribution, with equidistant speakers and also equally divided in angle disposition. It would, nonetheless, expand from the [pan~] object, and offer another dimension besides only angle/azimuth (like PanAZ from SC). I should offer just this more versatile object than. First question is, should this be called a "spatializer" and not a "panner"? It's a bit like 2D VBAP but it doesn't really compare, right?
Next step would be to offer a real VBAP external. Final step would be getting involved with "ambisonics". I could start with a 2D VBAP, based on options we have, but I would like to be able to gather the best of all worlds I found.
- Different room shapes with speaker position, not only angles for a ring
or semi ring setup
- Being able to set a point in the plane and not only an 'azymuth' panner.
- Being able to use an 'actual' spread parameter.
What I don't understand is why only CICM tools' [vbapan~] object has the option to set a cartesian point. And also why it can set an arbitrary disposition of speakers that is not just a single ring. Does anybody know why? Is the spread parameter in here somehow in a different or can I also include it?
Does anybody have other external options of similar objects that I mentioned here for me to look at? It can be a MAX object or whatever.
Also, good reference for spatialization tutorials and stuff is highly welcome.
Thanks