Re: Never normalize to 0dB?

Don Pearce wrote:
Some real enlightenment is to be found here

http://www.audiomisc.co.uk/HFN/OverTheTop/OTT.html

Thanks. That's more the kind of discussion I was hoping for.

After reading about the cases of the 1812 Overture and Queen
recordings, I decided to try another kind of artificial test
file. I put a 1 kHz, -6 dBFS sinewave in one channel, and a
1 kHz, -6 dBFS square wave in the other.

Here is a cycle of the waveforms from the .wav file, as
viewed in Audacity:

http://jayts.com/images/Sine_Square_1kHz-5dB-Audacity.png

And here is the waveform, played at full volume with VLC
and as viewed by Zelscope, recording the audio card's inputs:

http://jayts.com/images/Sine_Square_1kHz-5dB-Zelscope.png

When played into my Tektronix oscilloscope, I measured +1.9 dB
excursions in the square wave, beyond the amplitude of the sine
wave, in both the rising and falling edges of the square wave.
This matches what the author of the Over The Top webpage says
he found in the recordings: "The results show excursions reaching
peaks up to +2dBFS [sic.]."

I used a 1 kHz square wave because I was thinking imaginatively that
guitars reach up to around 1500 Hz at the 24th fret of the high E string.
Put that through some heavy metal distortion, and process it
carelessly, and you've got something very close to a square wave
(that is, with the tops and bottoms clipped to horizontal, flat lines
somewhere in the digital world). Toss that into the "loudness wars", and
you'll have the flat lines "normalized" to 0 dBFS.

There are two things on my mind now:

1. Have we been doing normalizing wrong? Waveform editors are
happy to show waveforms as "connect the dots", essentially
using a pencil and ruler technique. This is not really correct,
and leads the user into a false sense of confidence. Worse, they
also are happy to "normalize to 0 dBFS", when they are actually
normalizing to maybe +2 or at the extreme, +5 dB.

Is it time we bugged the programmers for a WYSIWYG waveform
view, and a "smart normalize" checkbox in the normalize
function's dialog box?

2. Even if the output device's D/A converter clips the waveform,
is that clipping ever actually audible? In most cases, it's
just 2 dB at most, and it's happening at a very high frequency.

In both the WFH and the waveform I showed earlier, the
oscillations that are sending the signal over 0 dB are at
about 20+ KHz. Harmonic distortion resulting from the clipping
produces a 2nd harmonic around 40+ KHz. It may be audible to
insects and bats, assuming it makes it through the player's
analog output circuit.

So again, is this really worth caring about?

Jay Ts
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http://www.jayts.com/contact.php
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