[Vorbis-dev] Ambisonics in Ogg Vorbis

[Richard Lee]

> I have done. How does that relate to my pointing out the fact that
the W channel is stored 3dB down in an .amb file? Well, it changes
the decode, doesn't it?

In "SHELF FILTERS ... ", I use WXYZ in its strict Ambisonic sense as defined in 

http://www.york.ac.uk/inst/mustech/3d_audio/secondor.html

Please use these strict definitions when talking about Ambi decodes.  I don't use anything else.  If I do, I point it out clearly.

>By the way, that document boils down to putting a low-pass filter on
the W channel.

No.  What my document says is that if you make these very simple changes to the decoding (and proper Shelf filters are simple only if you are a DSP guru) you will get better localisation.  See

"Localization in Horizontal-Only Ambisonic Systems" - Benjamin, Lee & Heller  AES oct06 San Francisco

from

www.ai.sri.com/ajh/ambisonics

has the experimental evidence.

Your decoder is OK but an Energy decoder is better and an Energy decoder with Shelf filters is better still.


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