[linux-audio-dev] TAP Scaling Limiter - how's it work?

Tom Szilagyi tszilagyi at users.sourceforge.net
Wed Feb 18 17:46:47 UTC 2004


Paul Winkler wrote:

>>The fact is, if you have a
>>normal musical signal, it will have much higher frequency components so
>>zero-crosses occur much more frequently than this limit. I investigated
>>this problem a bit before i settled on that 40 Hz... a mixed signal
>>(a few instruments together), or higher pitched instruments usually
>>give average zero-cross frequencies of 8-12 kHz. 
> 
> that high? no kidding?

Yes, mostly, because higher harmonics also cause zero crosses. Musical
instruments are not sinusoidal waveform generators. :-) (also, the
numbers above were the average frequency of zero-crosses, which mean
actually half that audio frequency, because every cycle has 2
half-cycles... so that 8-12 kHz is not really surprising...)

> 
> Not too many instruments get  below 40 Hz that I know of ... synths 
> and pipe organs, mostly. And they *usually* have a lot of higher
> freqs mixed in.

That's why there is many zero-crosses in almost any case... more than
what the instrument's base frequency would yield.

>>So if you take a 30 Hz sinusoidal from an oscillator and feed it into
>>this plugin, then there will be unprocessed segments 
> 
> just one, right?
> 

One per LADSPA buffer, in the worst (but not very unlikely) case.


Tom




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