I made a cheap vanilla zero crossing patch some time ago. it doesn't work properly if the signal has zero samples between crossings though.
Martin
Roman Haefeli wrote:
On Tue, 2010-08-17 at 13:59 +0200, Matteo Sisti Sette wrote:
On 08/17/2010 01:39 PM, Roman Haefeli wrote:
On Tue, 2010-08-17 at 12:59 +0200, martin brinkmann wrote:
i will try this when i have found a way to extract single-cycle waves from audio input in pd...
Not yet tried it myself, but what about writing live input to a table (for instance with [tabwrite~]) in order to have access to the audio data with message based objects? With those it should be fairly easy to the detect the exact position of a zero crossing. For finding a single cycle, it would be sufficient to find a positive crossing - for instance- and from there find the next one, so you have the exact end points of one single cycle.
How would you look for zero crossings? With message based objects such as [until], a counter, [tabread] and comparing to zero? Is that feasible?
(sorry for hijacking the discussion, I am curious about that)
yeah, actually that's what I thought about. I guess, one would not compare to zero, but compare to the previous sample and check whether the sign has changed. One could even perform linear (or even polynomial interpolation) to find the subsample accurate location of the crossing.
Roman
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