Apple Final Cut Pro 7 - Manual (Page 866)

• Average loudness: The average loudness of a clip generally determines its overall
perceived volume, and this is probably somewhat lower than the level of the peaks. In
the sample waveform, the level of average loudness appears as the densest, darkest
part around the middle. Average loudness, rather than the brief peaks, tends to influence
your decision about mixing a sound higher or lower.
Analog Versus Digital Meters
The way you set your levels with a digital meter is different from the way you set levels
on an analog meter. Compare a traditional analog audio meter with a digital audio meter:
Generic
VU meter
Digital
audio meter
−30
−20
dB
−10
−7
−4
−2
0
+2
+4
+7
−66
dBFS
−36
−24
−18
−12
−6
0
−48
A digital meter displays the sample values of a digital audio signal. The scale on the meter
is known as digital full scale, and the signal is measured in dBFS. On this scale, 0 dBFS
represents the highest possible sample value. Any samples above 0 dBFS are clipped,
distorting the original shape of the audio waveform. Once a signal is clipped, the original
shape of the waveform cannot be recovered.
0 dBFS 0 dBFS 0 dBFS
Original Too much gain
causes clipping. Clipping remains
after gain is reduced.
Important: Final Cut Pro can handle digital audio levels above 0 dBFS by internally using
32-bit floating-point resolution for all audio processing. However, when you export or
output to tape, the bit depth of your audio is usually reduced to 16 or 24 bits, so you still
need to be aware of the 0 dBFS limit.
866 Chapter 54 Evaluating Levels with Audio Meters