Re: [LAD] Multi-Channel channel order

David Robillard wrote:
> On Sat, 2009-08-15 at 01:04 +0200, Fons Adriaensen wrote:
>> On Fri, Aug 14, 2009 at 05:44:21PM -0400, David Robillard wrote:
>> Another outcome of the Graz meetings is that the port groups
>> that are currently named H#V# should really be named H#P#.
>> The H#V# ones do also exist, but are different. I'll have to
>> rename all existing AmbDec presets for the same reason.
>
> Do you have a link or anything about this? (What does the P stand for
> etc)

the old approach to mixed order was to have a horizontal-only
higher-order set and a first-order full periphonic set.

that means if a source is on the horizontal plane, you benefit from the
higher angular resolution of higher-order, but as soon as it moves up or
down, you are back to first-order. bad.

the new scheme as proposed by travis makes sure that you have full
higher-order azimuthal resolution at all elevations, but only
first-order elevational resolution. the only downside is that it uses
more channels.

the paper is here:
http://ambisonics.iem.at/symposium2009/proceedings/ambisym09-travis-newmixedorder.pdf/at_download/file

now that the important difference between those two approaches has been
pointed out, it seems that the old shorthand notation needs to be changed.

we used to write *3h1v*, which was supposed to mean 3rd-order
horizontal, first-order vertical. but outside the horizontal plane,
there is no 3rd order at all. so the correct new shorthand is *3h1p*, to
be read "*3*rd-order *h*orizontal components, superimposed with a
*1*st-order *p*eriphonic set".

the improved scheme by travis will now be denoted as *3h1v*, which can
be read as "*3*rd-order *h*orizontal resolution at all elevation levels,
combined with *1*st-order *v*ertical resolution at all azimuths"...

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Received on Sun Aug 16 16:15:02 2009