[LAU] Surround Mixing & Ambisonics

[Jörn Nettingsmeier]

Ray Rashif wrote:
> Good day all
> 
> I've recently gotten interested in recording & mixing in surround, which
> led me to Ambisonics as well. I've noticed Fons has a good deal of
> contribution to that field, judging from his tools (ambdec et al) and
> credits.
> 
> My first stumbling block is how one would go about the mixing process
> for such a project, especially since none of our DAWs have (true)
> support for surround. Granted, there are ways to work around it,
> especially if one doesn't need fancy 360-degree panning UIs. For
> instance, although I've not tried it yet, theoretically one can stream
> separate tracks to ac3jack. Each track can have its own panning relative
> to front and rear groups, and since conventional surround (not
> ambisonics) has no height information, that'd be adequate. I don't know
> if existing surround VST plug-ins could be used within Ardour properly.
> 
> Secondly, would the tools from http://www.kokkinizita.net/linuxaudio/ be
> enough for ambisonics? I notice that there is only a decoder, but for
> mixing, one needs an encoder (which I understand to be the panning and
> bussing of WXYZ). Is there any native tool to help with that?

i've been using ambisonics in ardour quite a lot. check out fons' AMB
plugin set (and its README). here is a paper i did on this topic:

http://stackingdwarves.net/public_stuff/linux_audio/ambisonic_organ_remix/joern_nettingsmeier-shake_rattle_and_roll.pdf

slides:

http://stackingdwarves.net/public_stuff/linux_audio/ambisonic_organ_remix/joern_nettingsmeier-shake_rattle_and_roll-slides.pdf

and a video from lac 2009:

http://stackingdwarves.net/public_stuff/linux_audio/ambisonic_organ_remix/Joern_Nettingsmeier_-_Shake,_Rattle_and_Roll:_An_Attempt_to_create_a_spatially_correct_ambisonic_mixdown_of_a_multi-miked_organ_convert.ogv

it's third order, for which the plugins are not yet released, but that
should happen rsn.

> Third and _most_ important of all, is it possible to listen to the
> _virtual_ surround image in real-time through stereo? IIRC, Windows
> has/had these neat little utilities provided by vendors to recreate 3D
> (virtual) surround with n number of speakers, marketing to the 2-channel
> stereo crowd. Any surround audio being streamed by the system would fall
> back to this 3D thing if no surround hardware is available. Not sure
> whether the same applies for an ASIO environment. If not, I may be
> asking for something which has not yet been developed.

for any remotely professional application, the only thing that makes any
sense is a binaural rendering. which you can do using supercollider or
pd, but it's quite an undertaking.

> Considering that ALSA has a "plug-in" for downmixing multi-channel
> audio, and it works OK, could there be a way to use it/something similar
> within a JACK environment? It'd really help when I'm recording live, eg.
> an orchestra, with surround miking and no more than just a monitoring
> headphone. Something like ac3jack, but with some sort of virtual
> surround output option.

a little fairy has whispered in my ear that the upcoming release of the
AMB plugins may have what you're looking for :-D