Re: [Csnd-dev] [EXTERNAL] [Csnd-dev] UDO local sr

Hi Anders,

There is now an undersample opcode to go along with the oversample. I am not sure what you mean about 2., it does allow
a-rate opcodes.

best
========================
Prof. Victor Lazzarini
Maynooth University
Ireland

> On 20 Mar 2024, at 08:55, Anders Genell <[email protected]> wrote:
> 
> *Warning*
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> This is mainly for Victor Lazzarini, 
> 
> I saw you added code in a PR to implement local sample rate in UDOs which I think is absolutely fantastic.
> It seems there are two limitations that I really hope could be addressed in the future:
> 1. The code allows for upsampling but not for downsampling
> 2. The code does not allow for a-rate opcodes
> 
> The use case I am hoping will be possible in the future is when having a reasonably high global sr (say 48kHz or even 96kHz) where I would like to apply relatively narrow band filters with center frequencies at say 20Hz, 25Hz 32Hz or the like. Such filters tend to be somewhat unstable at such high SR if they also need to be reasonably steep, and by downsampling before filtering a better result is often achieved. This is commonly done in signal processing for analysis in e.g. Matlab or GNU octave.
> The idea is e.g. to be able to manipulate individual bands, like in the pvs group of opcodes, and combining the individual bands back to one signal afterwords, so just docking global reduction of SR would not be a viable route, unless of course starting several instances of csound and using channel opcodes to combine everything in the end.
> 
> Would this be a possibility in some future iteration of the newly implemented code?
> 
> Regards,
> Anders