--- John Rigg <[EMAIL PROTECTED]> 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. Send instant messages to your online friends http://uk.messenger.yahoo.com
