[Vorbis-dev] 5.1 surround channel coupling

[Gregory Maxwell]

On 2/28/07, Richard Lee <ricardo at justnet.com.au> wrote:
> > Is there any reason why the panner shouldn't have a default
> configuration matching the standard ITU layout and only expose the
> fully flexible layout as an advanced option?
>
> There are 2 important reasons for not doing this
>
> 1)      No one has an ITU layout at home.  The only one I know of is in a big research lab.  I discuss this in "Ambisonic Surround Decoder" under Real World Systems
>
> www.ambisonicbootlegs.net\Members\ricardo
>
> 2)      It doesn't give as good results as simple 4.0 square.  This is predicted by Ambisonic theory.  That's why 5.1 can't put images at the sides.

You misunderstand my post.

The patch that I'm referring to allows you to take a set of 5.1 --
zillion.1 speaker feeds as input, specify a speaker layout, then it
uses an ambisonic panner to produce an ambisonic rendition of these
feeds for encoding.

I was suggesting that the default options simply place the speakers at
the standard "virtual" locations... but it turned out that the
software already does this.

Obviously on the decode side they layout should be flexible enough to
cover any sane configuration, since as you note most listeners do not
have the standard layout. This is one reason why it makes sense to
convert native 5.1 signals to b-format prior to redistribution.