Hello,
In order to build a variable speed sound-on-sound looper I was looking for an object that can write at fractional speed, analogous to the interpolated reading of [tabread4~]. Indeed I found C code for [tabwrite4~] in ggee/experimental, but a quick test revealed that it doesn't work properly. In a flash of optimism, I planned to rewrite the code, but soon stumbled upon questions.
It seems to me that 4-point-interpolated writing would mean: write values to 4 indexes at a time, just like [tabread4~] reads from 4 indexes at a time. While writing 4 values, recently written values must be taken into account, not bluntly overwritten. So two existing values, x[n-2] and x[n-1], should be somehow integrated with new values, if the writing direction is positive. That should be a leaky integration. Imagine the write pointer doesn't move; the values should not build up then. But how much should it leak to get the right balance?
Does anyone have knowledge of this? It would be cool to have [tabwrite4~] in Pd-extended. I'm prepared to spend time on it, if someone can assure me that the concept is viable at all.
Katja