> I would be very interested if someone could do a filter library =) I'm a
> bit fed up with the lopass and hipass ones ;)
Guilty as charged :-). More importantly, though, lopass and hipass are
part of a short list of SAOL opcodes that aren't normative -- each
implementation can compute whatever algorithm it pleases, and so
programs that use them will indeed sound different everywhere. Here's
a list of the core opcodes with non-normative characteristics (I
believe this is complete, if someone sees an omission please chime
in):
aopcode hipass
aopcode lopass
aopcode bandpass
aopcode bandstop
aopcode reverb
aopcode chorus
aopcode flange
aopcode fx_speedc
iopcode speedt
In addition, in a minor way aopcode compressor is non-normative
(the "knee" of the curve between the gain=1 and gain=ratio
regime is left to the implementor to specify), and the
only interpolation method that is normative is linear interpolation
(which is the default, or can be set explicitly with the global
parameter "interp 1"). Setting "interp 2" results in a method
the standard says should be "better than linear", and leaves it
up to the implementator to define further.
I believe if you avoid everything above, you'll end up with a
fully normative composition, that any compliant decoder should
render identically as defined by the standard. Hmm, this would
be a good feature for sfront to add -- a mode that warns people
when they are doing something non-normative ...
--john lazzaro
This archive was generated by hypermail 2b29 : Mon Jan 28 2002 - 11:46:36 EST