[LAU] ambisonic and jconv

Fons Adriaensen fons at kokkinizita.net
Sat Mar 21 05:30:14 EDT 2009

On Sat, Mar 21, 2009 at 09:53:12AM +0300, alex stone wrote:

> Ok, had the head in the amb manual and online reference material, when time
> permitted, and have another question.
> How do we handle early reflections when using an Ambisonic Jconv instance?
> I'm experimenting with the yorkminster-amb.conf (wonderful clear sound), and
> i don't yet understand how we create, or use, early reflections from the
> same instance. (If indeed this is required.)

The York config includes the early reflections. Of course they
are fixed for one source positions. Using the delay, offset and
lenght paramters you could split it up so you have a separate
input for the E.R.  For example (only W channel shown, the 
rest are similar):

#               in out  gain    delay  offset  length  chan      file  
# ---------------------------------------------------------------------
/impulse/read    1   1   0.100     0    3480   4800     1    Minster1_000_WXYZ_48k.amb
/impulse/read    2   1   0.100  4800    8280      0     1    Minster1_000_WXYZ_48k.amb

The first line selects the first 100 ms (which will contain the E.R.),
the second line is the reverb tail without the firtst 100 ms.
If you send the same signal to inputs 1 and 2 the result will
be the same as before, but now you can set each level separately.
For a large space such as York Minster there would be discrete
reflections  even well after 100 ms, so you could increase the
4800 and 8280 (= 3480 + 4800).



Laboratorio di Acustica ed Elettroacustica
Parma, Italia

Io lo dico sempre: l'Italia è troppo stretta e lunga.

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