Subject: Re: [ecasound] ecatools addition - ecasignalview
From: Kai Vehmanen (k@eca.cx)
Date: Sun Dec 03 2000 - 17:05:51 EET
On Fri, 1 Dec 2000, Jeremy Hall wrote:
> one more time, it has been a while, please could you explain the pos/neg
> thingie? WHat does it mean?
Positive and negative amplitude values. I'm not sure how useful this
really is. If you have a huge DC-offset in your signal, you'll notice this
right away as there are more samples on the neg/pos side. On the other
hand, ecasignalview could just calculate the DC-offset and show it as a
single value.
> also, while on the subject, I have noticed that when capturing,, it says
> 0.99997 instead of >=1 I dunno when this happened, but was some time
> ago. Is alsa compressing my input for me? :(
Hmm, what says? :) This is probably caused by ecasound's int->float
conversion. When converting an integer value with range of [-32768,32767],
ecasound could either divide by 32768 or 32767. I've chosen to divide
by 32768, so that the resulting mapping is [-32768,32767] -> [-1,0.99997].
More generally, ecasound divided a signed integer by 2^(n-1), where n is
the number of bits used to represent the integer.
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