On 01/16/2015 12:23 PM, Alessio Degani wrote:
Hi list,
[...]
When you want to write a PD external that process audio stream, the scenario is: 1- PD passes chunked audio stream to the inlet of the external and read an audio chunk from the outlet of that external. Each input and output chunk is of fixed length of, say, Nc samples. Each chunk is a NON-overlapped adjacent chunk of the audiostream to be processed.
i hope you are aware that this is a simplification on your side, and not how Pd handles audio streams (when it comes to overlapping)
My question is: There is a standard way, a "design pattern", to manage this kind of processing?
i don't know of a standard "design pattern" but there are two ways that come to my mind:
- implement a ring-buffer where you put the sample chunks delivered by
Pd, and read/use them whenever you have collected enough data. overlapping is very simple to implement (as long as you don't overwrite the data :-))
- let Pd do the partitioning and overlapping.
this should be the preferred way, but obviously only works if you can live with Pd's constraints regarding overlap (overlap-factor mus be a power-of-two). you should make your algorithm accept any block-size that Pd accepts (any power-of-two); if this does not work for whatever reasons, you could simply check whether the user has set the correct blocksize/overlap when DSP is turned on, and refuse to work if the settings do not match your expectations (and print an error() so the user knows why it's not working). (the main drawback with this approach is, that there is currently no entirely sane way to uniquely identify the overlap factor. as long as now re-sampling is used, it's fairly easy though)
gfmdar IOhannes