Re: kAudioUnitID_BandPassFilter
Re: kAudioUnitID_BandPassFilter
- Subject: Re: kAudioUnitID_BandPassFilter
- From: SKoT McDonald <email@hidden>
- Date: Fri, 11 Jan 2002 14:56:50 -0500
Depending on the implementation, there is usually a "roll off"
(for example, 6dB/per octave for a simple filter) outside the passband.
frequenceis between 4400-5600 will be minimally touched. It is
possible to get steeper/shallower roll off rates with various pros and
cons. it would be interesting to hear about the filter parameters and
implementation in the coreaudio case (it could be in the doco - haven't
looked yet! apologies in advance)
- SKoT
On Friday, January 11, 2002, at 02:12 PM, Lieven Dekeyser wrote:
Hi!
Maybe this is a stupid question but I really don't know much about
audio processing :-)
What frequencies does a BandPassFilter AudioUnit with center frequency
5000 and bandwidth 600 filter?
Does it cut out exactly all frequencies below 4400hz and above 5600hz
and
leave those between 4400 and 5600 untouched like
this: (sorry about the ascii art ;) )
_____
| |
_____| |_____
^
5000hz
or is it more like this:
_____
/ \
___/ \___
^
5000hz
?
the reason I'd like to know is I would like to implement something like
the equalizer in iTunes, so I'd take some Band Pass filters each for a
different frequency interval, pass the audio data through them, and then
mixing the output back together adjusting the gain. Is this the right
way
to do it, or are you all laughing at me right now? :-)
--Lieven
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