--- John Rigg <ladev@email-addr-hidden-man.co.uk> wrote:
>
> Don't have a pointer, but wouldn't a simple linear
> interpolator followed by a basic LPF do it fairly
cheaply?
>
It might if we only needed to do the control signal,
but at 44.1, there just is not the bandwidth in either
the control or AUDIO channels to alllow fast gain
changes. Therefore we need to upsample both the audio
and the control data (albiet that the control
upsampler can get away with a lot less bandwidth then
the audio one).
When we hit that multiplier the condition is that the
sum of the audio bandwidth and the control bandwidth
must fit within the nyquest limit, at 44.1 ther just
is nothing like the required bandwidth at this point.
With both the audio and control bandlimited to 0.25 *
FS, we can safely multiply them, any more then that
(split any way you like) and it all falls apart.
With respect to viewing the attack and decay logic as
a LPF, this is only the case if the same timeconstant
applies to both (seldom the case), as otherwise there
is a discontinuity in the rate of change at the
transition which will itself generate HF splatter.
It is a thorny problem.
Regards, Dan.
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Received on Wed Oct 18 00:15:08 2006
This archive was generated by hypermail 2.1.8 : Wed Oct 18 2006 - 00:15:08 EEST