From: Steve Sneed <[EMAIL PROTECTED]>
Subject: RE: Audio Compression, Normalization Caution
I would agree with Harry that normalization shouldn't always be used, =
but it should not be ruled out. First, let's be clear that =
normalization and audio compression two very different things. =20
Normalization is a "..digital process of boosting the highest peak =
signal to the maximum bit level of the system then proportionately =
changing the soundfile gain by this value" [Hard Disk Recording- D.M. =
Huber] Note that this is not just turning up the volume. You make =
full use of the maximum resolution of the file, whether it's 8 or 16 =
bit. A low level sound recording at 16 bits will have an effective =
resolution that is much lower. =20
Any recording that is lower than the maximum resolution, regardless of =
whether it's digital or analog, carries some element of noise with it. =
But sometimes a crappy, low level file is all you have to work with. =
Normalization is somewhat of a crutch to assimilate a properly recorded =
file. If your digital audio editing tools are operating correctly, a =
95% normalization will give you a much stronger audio file AND prevent =
clipping during the encoding process. However, if you normalize at =
100% of the available bits and you WILL experience transients, =
artifacts, and clipping every time.=20
*TIP* I picked up a tip some time ago that said if you need to apply =
normalization, do it last. Applying any other digital processing =
(excluding encoding) after normalization will fuzz the sound. =20
Audio compression.. I could get technical, but in layman's terms =
compression limits the loud parts and boosts the low levels. This is =
different from normalization in that you control at what level to boost, =
limit, attack (start), and release the sound. The net result is a =
consistent volume level throughout the entire sound file. To use a =
visual analogy of compression, think of a wave file shaped like a sail =
fish. The loud parts are the fins and the quiet area the back of the =
fish. After complete compression, this wave file looks more like log. =
Obviously, you don't want to compress that much, but I hope you =
understand the analogy. Under normalization, our sail fish would just be =
a bigger sail fish.=20
A typical function of compression is to raise or lower the resulting =
output. After correcting DC offset, this is typically my next process =
in getting a solid, full, and loud sound file. =20
*TIP* All digital audio files are not created equally. Therefore, the =
order and selection of processing won't be exactly the same every time. =
Many times when my typical routine fails to produce an acceptable =
sound, I will switch the order of processing or drop a step altogether. =
I wouldn't make a very good lab rat.
I hope this helps to clarify.
Steve Sneed
612-942-8738
[EMAIL PROTECTED]
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