Allpass Interpolation - Help

[Z1202]

Phasers are rather nasty case of zero-delay actually, because unlike most regular filters the BLT warping tends to cause trouble with phasers, because there isn't a single cutoff that you could sensibly warp. Obviously enough oversampling will cure anything, though..

Does it really cause trouble? Okay, the distance between the notches might get slightly wrong, but I don't think it affects the sound in a noticeable way (compared to a unit delay in the feedback ) I'd just choose the formal cutoff of the underlying allpasses (if they all use the same one) or some kind of average value as the prewarping point.

Regards,
{Z}

[Ichad.c]

Phasers are rather nasty case of zero-delay actually, because unlike most regular filters the BLT warping tends to cause trouble with phasers, because there isn't a single cutoff that you could sensibly warp. Obviously enough oversampling will cure anything, though..

I told you not to answer that! Probably can't help yourself

Anyway oversampling in theory goes like this:

You're the 4th person to tell me this in a month
The theory I've read and understood about 8 years ago - like you are a compulsive filter-solver - I'm a highly curious compulsive reader. I've probably read every significant audio patent from about the 50's to the 90's, every manual for every piece of gear I own(except 1) or ever wanted to own, every technical paper even remotely related to anything I was/is doing at any time - even if I don't get 70% of the math or techniques in technical papers - I'll still just read it for fun

My problem is I've only done c++ for about 2months now - learn't it via reading. Was planning to do a short 6month c++ night-course at a local University - but they cancelled it - due to "lack of participants". So I'm left to my own devices - which is like giving an autistic kid - a stick of dynamite to play with
Pointers and buffers sometimes confuse me. And with the SE SDK3 - I have to (for 4x Oversampling) - create a buffer 4x times larger - probably take the data from the "given" buffer - put it into the BigBuffer - then point into the buffer at four points to add the zeros - filter - process whatever - filter if non-linear again - then take out the 4th sample again, then increment everything. I have about a 95% probability of stuffing up any pseudo-code - so practical help from somebody that actually understands the SDK is probably the only way I'll ever get oversampling working. For interist's sake the code I posted in the beginning of this thread - is the SDK3 format.

Thanks for trying to help though!

Regards
Andrew

[camsr]

Hi Ichad.c, have you made any progress with this?

[Ichad.c]

Do you mean the allpass-interpolation or the oversampling?