Re: Out-of-range samples
Re: Out-of-range samples
- Subject: Re: Out-of-range samples
- From: Erik Rose <email@hidden>
- Date: Mon, 30 Jan 2006 10:01:40 -0500
Just as a practical matter, blowing into a good microphones is a
good way to ruin it;
That's good to know; thanks.
although, the one built into a Powerbook is probably safe. Blowing
into a microphone (and wind) will produce unusually high output.
That's what I was going for, of course. I was trying to empirically
find the limits since they aren't prominently documented.
In general, the range of signal values that can come out of a
microphone is way too extreme to run directly into a recording
process of any sort (including a LAME converter). At a minimum,
you need some sort of gain control and signal metering to see what
the levels actually are. Things like compression, limiting and/or
AGC are often useful (depending on what you are trying to do).
I'll ultimately have at least manual gain control and, if I get
ambitious, normalization after the fact.
It is odd that the driver for the built-in mic is producing such
high sample values. The driver must have a built-in gain control
that is set very high. You should be able to access the gain
control in AMS.
Unless I have a profoundly mistaken view of the universe, CoreAudio
should stay within its amplitude limits no matter how high the gain
is cranked up. If the gain is too high, it should, at worst, clip,
yielding ones and negative ones. I take it you haven't encountered
these out-of-range values?
Erik
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