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> Also, there has been some recent work on channel mappings for OggPCM (uncompressed PCM data in an Ogg container), which may be related: Our proposal involves only Vorbis. Uncompressed PCM Ambisonics is already well catered for. > It is indeed related. We are proposing a different ambisonic channel scheme (not speaker mapping though) called N3D (different to the usual FuMa scheme). The

Where can I find the Header file or whatever which specifies the "Mapping" flag. In feb - apr 2007, there was a lot of discussion about Ambisonics and Monty kindly stated that Mapping = 1 ; Denotes and Ambisonic file as opposed to = 0 which is 1 speaker/ 1 channel Has this been written explicitly into the standard? Which standard should I be looking at?

>Yesterday I have finished writing the ambisonic pan filter for oggenc. May I ask what this "pan filter" is? I made some tentative suggestions for coupling Ambisonic B-format in a post "Vorbis Ambisonic coupling" on 4feb07 I gather from the last monthly meeting, that some of you, including Monty, had problems with the phase behaviour of B-format. Would anyone like a

A strategy for downmix support a) simple 4.0, 5.0, 6.0 7.0 Speaker Decode on the player via a separate library from the Vorbis core. This is the easy panning solution on the Wiki Ambisonic Decoder page and requires hardly any computing power. Most important cos its all about surround init? This library can be extended to have Shelf Filters & Distance Compensation for more sophisticated

> I assume, somewhere, someone has a compendium of recommended hardware for ambisonics? Something to sanity check/inform equipment selections of someone building My First Ambisonics Rig? Not at all Monty. This is an important question and I am ashamed to say I can't point you to a good answer. In the meantime, have a look at Permananent Ambisonic Systems from

>I have been giving some thought to how to include Ambisonics in Ogg Vorbis. As I understand it, mapping type = 1 was meant from the start to indicate an Ambisonic stream. The only other information required is the number of channels which thanks to Mr Leese's clever trick tells us exactly which Ambisonic channels are used up to 3rd order. __________________ >The channel coupling

Richard Lee wrote: > But there is a caveat. Does Vorbis coupling preserve "phase" relations? Any references explaining this in simple detail? Sebastian : >"coupling" is a rather loose term in the sense that it doesn't exactly specify HOW it's done. It can be understood as the opposite of coding channels independently. Obviously there are many ways to do